Category: Evolution

What's a "Species"?

5/29/2015

The naming of a new species of hominid -- Australopithecus deyiremeda -- made a lot of news this week. The purpose of this post is not to worry over the details of the fossils that were used to construct this new taxon, but to ask for some clarification about what is actually meant by the term "species" as paleoanthropologists use it. I'm going to tell you what I think it means, then I'm going to complain about it a little bit, then I'm going to ask you to tell me what you think it means. (Full disclosure: I fall at the lumper end of the lumper-splitter spectrum, and I think there are too many named "species" in our family tree.)

In their paper, titled "New Species from Ethiopia Further Expands Middle Pliocene Hominin Diversity" (Nature 521:483-488), Yohannes Halie-Selassie and colleagues use the word "species" 17 times but provide no explicit definition of the term. What is a "species"? What are the implications of defining a "new species" of hominid?

Like so many other things, it depends. There exists a smorgasbord of different species concepts to choose from. A "typological species," for example, is a classification based on the co-occurrence of shared features, while an "evolutionary species" is defined based on the integrity of an ancestral lineage (without branching, there is no new species). A "biological species" is generally defined as a group of organisms that can breed with one another but not with other groups of organisms. In other words, a biological species is reproductively isolated from all other biological species. The biological species concept is perhaps the one most frequently applied in biology, especially to living populations of plants and animals.

I think a "biological species" is also what most people, paleoanthropologists included, mean when they talk about "species" of hominids.

The distinctions among the various species concepts are not just academic when they're applied to fossil hominids. They have implications for our notions about what variability means in the fossil record and how we interpret that variability in terms of the patterns and processes of human evolution. Because reproductive isolation is the entire basis of the biological species concept, individuals in a biological species (by definition) could not and did not interbreed with any of their contemporaries outside their own species. There cannot be multiple, co-existing species of human ancestors: a "new species" is either a human ancestor or somewhere off on a side-branch of our evolutionary family tree. The discovery of a human ancestor that pushes someone else off onto a side branch is much more exciting that the discovery of another non-contender. You can see that in the enthusiasm of headlines about Australopithecus deyiremeda such as "Doubt cast on Lucy's place in human evolution" and "New hominid discovery older than Lucy raises more questions on human ancestry." They might as well read "Don't let the door hit you in the ass on way out, Lucy."

I'm not an expert on paleoanthropology, and I've never directly analyzed or attempted to describe or classify the remains of a fossil hominid. But I am someone who regularly attempts to describe variability (mostly in lithic artifacts) and make sound interpretations about what that variability means. In any case, when you're looking at continuous variability, you can split all you want. There is easily detectable variability in just about everything not produced by a machine, so ultimately it's no great feat to break continuous variability down into as small of groups as you want (groups of one, if that makes you happy). But what do those groups mean? That's a hard question to answer without having a sample of a decent size that let's you investigate how the variability you're looking at is structured. That's why I'm a fan of trying to understand how variability is structured before trying to create groupings that have some analytical value.

The pitfall of aggressive splitting of the fossil record is that the groupings you produce (the biological species) are tied to important assumptions about the processes that produced those groupings. While I think the biological species concept is one that is clear and makes ecological and evolutionary sense, I also think its uncritical application to the fossil record is less than useful. First, I think it's impossible to operationalize consistently and objectively (how can you determine if the populations represented by fossil individuals were capable of inter-breeding?). So I don't trust that "species" that are equivalent in taxonomic terms reflect populations that are equivalent in evolutionary terms. Second, I think naming lots of "species" short-circuits our study of what variability in the fossil record means by erring on the side of attributing it to species-level differences. Under the biological species concept, species are non-overlapping, nominal categories, and speciation is a one-way street. By calling a fossil hominid a new biological species, you are making a statement about the nature of the relationship between that fossil and all other fossil hominids. Given the sparse nature of the fossil record, I don't think that we can really make those kinds of statements with much confidence. Using the scalpel of the biological species concept ties us to those assumptions, however.

So I'm very skeptical of the reality of the number of named species that currently inhabit the hominid family tree. How many are there now? Twenty? Thirty? More? I wonder what would happen if we started fresh and re-analyzed all the Pliocene and Pleistocene hominid fossils discovered over the last 120 years. What would the structure of variability look like, and how would we interpret that variability if we erased all the existing species names and the historical legacies of discovery that accompanied them and based our groupings on patterns of variability across time and space? Who knows. I also wonder how many "species" of domestic dogs paleoanthropologists would define given a sampling of their bones.

Anyway, splitters be splittin,' and there's not much I can do about it. When I taught my 200-level Human Origins class last year, I made the decision to focus not on the minutiae of "species" in the fossil record, but on what various lines of evidence could tell us about the timing, processes, causes, and effects of changes in human anatomy and behavior over evolutionary time. We talked about species concepts and why they matter, and I gave my class my opinion that we're too quick to name new species and perhaps too reluctant to first look at what variability might mean outside the constraints of a species-level classification. Is Homo antecessor a legitimate "biological species"? Is the Homo erectus/ergaster division useful? If we know that Neanderthals and Homo sapiens exchanged DNA, why are we still calling them separate species?

Maybe I've wrongly identified the dominant species concept that is active in the background of paleoanthropological thought. Maybe a new name isn't meant to assume reproductive isolation and all that that implies. If I've gotten it wrong, please correct me. Maybe I missed something somewhere. In my own published work, I've been asked to provide clarifying definitions for such controversial terms such as "household," "process," "model," and "projectile point." President Clinton famously debated the meaning of the word "is." Is it too much to ask for a clarifying definition of "species" when we define a new one?

Update (6/5/2015): This post was discussed in Barbara King's blog post for NPR titled "Declaring The Discovery Of A New Species Can Get Tricky."

Haile-Selassie Y, Gibert L, Melillo SM, Ryan TM, Alene M, Deino A, Levin NE, Scott G, & Saylor BZ (2015). New species from Ethiopia further expands Middle Pliocene hominin diversity. Nature, 521 (7553), 483-8 PMID: 26017448

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Human Evolution and the Stone Tool "Problem"

5/27/2015

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Photographs of some of the artifacts from LOM3 (Harmand et al. 2015:Figure 4).

The recent announcement of the discovery in stone tools in Kenya dating to 3.3 million years ago (MYA) has been greeted with a lot of fanfare. I first heard the story at some point earlier in the academic year, and I know there was a lot of buzz about it at the SAAs and Paleoanthropology meetings in San Francisco in April. The publication of a formal paper in Nature last week (“3.3-Million-Year-Old Stone Tools From Lomekwi 3, West Turkana, Kenya,” by Sonia Harmand and colleagues) led to a flurry of stories in the popular media. Many of those stories (for example this one in the L. A. Times) framed the discovery as one that "hints that anthropologists may have had the wrong idea about the evolution of humans and technology."

Spoiler alert: The stone tools from Lomekwi 3 are an important finding, but not a surprising one.

Hyping and over-simplification by the popular media of scientific findings are a fact of life, and I understand the need to find an "angle" for a summary story. I find the media's coverage of the Lomekwi paper particularly annoying, however, because of the general implication that the discovery of tools of that age somehow caught us all by surprise. It didn't. Anyone who has been paying attention to the field for the last few decades will not be surprised at all by the claims that: (1) there are stone tools that pre-date Oldowan; (2) those tools were probably not made by members of the genus Homo; and (3) the use of stone tools can be traced back to at least 3.3 MYA.

Let me be clear: this is a very important finding, just not a particularly surprising one. The tool assemblage from Lomekwi 3 (LOM3) fits very comfortably within an emerging picture of tool use pre-dating Oldowan and Homo. That picture has been coming into focus for decades now, thanks to a lot of hard work by many different scientists. The LOM3 tools make a significant contribution to that picture by providing a line of direct evidence that was previously absent. For the first time, we get some idea of what pre-Oldowan stone technologies might have been like. I think it was only a matter of time, however, and there will be a lot more coming down the road.

Why did we expect stone tools pre-dating Oldowan to be found?

First, as pointed out in the LOM3 paper, the 3.3-million-year-old age of the tools is consistent with the 3.4 MYA cutmarked bones from Dikika, Ethiopia that were reported several years ago. Not everyone accepts those cutmarks as legitimate (here is a John Hawks' post about the critique), however. I'm not a cutmark expert, so I don't really have a strong opinion. I'll just say that finding a stone tool assemblage in east Africa that dates to the same time period as the purported cutmarks mitigates the "but where are the tools?" question for me.

Second, the idea that only humans use tools (and therefore evidence of tool use should only be associated with the genus Homo) is an antiquated one that has been solidly falsified by studying living, non-human primates. The use of tools has been widely observed among wild chimpanzees, our closest living relative (and also among more distant relatives such as orangutans and gorillas). The most parsimonious explanation for the presence of tool-using behaviors in chimpanzees and humans is that those behaviors were also present in the Last Common Ancestor (LCA). If correct, that means that all hominids/hominins (as well as all members of the lineage leading to chimpanzees) had some capacity to make and use tools. If not correct, we need to explain the independent emergence of tool use in both lineages. I think the first possibility (that the capacity to use tools is a homology) is more likely, and makes it much easier to explain the widespread use of tools among great apes and some other primates. The LOM3 assemblage pushes our understanding of a particular kind of tool use (stone tool use) back in time, but it is by no means at odds with the general idea that all hominids had the capacity to use tools. It provides direct evidence, rather, to help evaluate hypotheses about the timing and nature of the evolution of tool-using behaviors that are peculiar to humans.

The presence of tool-using behaviors among several of our closest relatives suggests that the cognitive hardware required for tool use was present deep in the Great Ape lineage: it doesn't take a big, human-like brain to make and use simple tools. But what about other parts of our anatomy?

Comparison of human and chimpanzee hands.

Comparison of distal phalanges (bones at the end of the thumb) in chimps (Pan), gorillas, Orrorin, modern humans (Homo) and Homo habilis (OH 7) (source: Almécija et al. 2010).

Human hands and chimpanzee hands -- both of which are capable of making and using tools -- differ significantly in several ways. Walking on two legs has removed selection related to locomotion from affecting the human hand, allowing our hands to be more-or-less optimized for manipulating objects (e.g., making and using tools). As quadrupeds, chimpanzees operate under a different set of restraints. A chimpanzee's hand anatomy reflects compromises between an appendage that can be used to manipulate objects and one that has to function for both arboreal and terrestrial locomotion. Those demands of locomotion have produced a hand with long fingers and a stiff wrist: long fingers are useful for grasping branches while a chimpanzee is in the trees; a stiff wrist serves to accommodate the forces that are transferred through a chimp's hand while it is walking on its knuckles.

The features of a chimp's hand make it harder for a chimpanzee to exert precise control over objects. The long fingers make a human-like "precision grip" (where the pad of the thumb is opposed directly against the pad of the index finger, as when you hold a key) impossible. The stiff wrist places limitations on the range of mobility. Although chimps can be taught to make and use simple stone tools (e.g., Kanzi), their hand anatomy works against them.

One of the features of a human hand is the broad, flat distal phalanx of the thumb. Because of our precision grip (enabled by our relatively short fingers), we are able to exert a lot of force between our thumb and forefinger. The broad bones at the ends of our thumbs reflect those strong forces. The shape of the distal thumb bone of OH 7 was one of the criteria used to define Homo habilis in the original 1964 paper by Louis Leakey, Philip Tobias and J. R. Napier:

". . . the hand bones resemble those of Homo sapiens sapiens in the presence of broad, stout, terminal phalanges on fingers and thumb . . ." (Leakey et al. 1964:8).

As more fossil hands have been discovered in the decades that followed, it has become apparent that many hominids had "broad, stout, terminal phalanges" in their thumbs. The illustration above (from Almécija et al. 2010) shows the OH 7 thumb bone compared to the thumb of Orrorin tugenensis (a possible hominid from around 6 MYA), a modern human, a chimpanzee, and a gorilla. Orrorin had a broad thumb. What about robust australopithecines? Yep. Australopithecus sediba? Yep. It looks like there were a lot of hominids that may have had good features for tool-using hands. If Ardipithecus ramidus (4.4 MYA) was a hominid, it suggests that a chimpanzee's hand is in fact more derived from the ancestral condition than a human hand: the LCA's hand may have been "pre-adapted" for tool use with a pliable, mobile wrist. All that was needed to make the transition to a human-like hand was to shorten the long fingers (which could have happened in the process of shifting to a fully terrestrial adaptation) and broaden the thumb as a precision grip became possible. If tool use was at all important to our pre-Homo ancestors, the selective pressure to shorten the fingers would have been present all along, just less constrained once long fingers were no longer needed for a partially arboreal adaptation.

So it looks like the cognitive capacity for tool use among our ancestors was probably present by at least the end of the Miocene (in the LCA), and the changes to hand anatomy that allowed human-like grasping were well underway during the Pliocene (ca. 5.3-2.6 MYA). The discovery of stone tools dating to 3.3 MYA doesn't conflict with any lines of evidence that I know of suggesting when we could see the earliest stone tools. The interesting questions that we can start address with the publication of the information from Lomekwi, really, are the "who" and the "why" questions: Why did hominids start making and using stone tools? Which hominids were making these tools? And what did tool use have to do with other aspects of human and hominid evolution?

Harmand et al. (2015:314) find differences between the lithic materials from LOM3 and Oldowan, and propose that the technology be given a new name: Lomekwian.

"The LOM3 knapper's understanding of stone fracture mechanics and grammars of action is clearly less developed than that reflected in early Oldowan assemblages and neither were they predominantly using free-hand techniques. The LOM3 assemblage could represent a technological stage between a hypothetical pounding-oriented stone tool use by an earlier hominin and the flaking-oriented knapping behavior of later, Oldowan toolmakers."

The identification of "Lomekwian" tools is going to open up some new thinking about the roles of tool use in general (and stone tools in particular) in human and hominid evolution, not because stone tools at 3.3 MYA were unexpected, but because now we have some hard evidence of what those technologies might have been like. I don't work in Africa, but I'm probably not going too far out on a limb to suggest that there are plenty of places with mid- to late-Pliocene deposits that might be fertile ground for finding more direct evidence of these pre-Oldowan stone tool technologies. It's going to be great to watch that story emerge.

Harmand S, Lewis JE, Feibel CS, Lepre CJ, Prat S, Lenoble A, Boës X, Quinn RL, Brenet M, Arroyo A, Taylor N, Clément S, Daver G, Brugal JP, Leakey L, Mortlock RA, Wright JD, Lokorodi S, Kirwa C, Kent DV, & Roche H (2015). 3.3-million-year-old stone tools from Lomekwi 3, West Turkana, Kenya. Nature, 521 (7552), 310-5 PMID: 25993961

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The Dependency Ratio in Human Evolution

5/15/2015

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As far as I know, humans are unique among animals in having an extended period between weaning and being able to subsist on their own. We call this “childhood.” The long period of post-weaning dependence provides our large brains with a lot of time to mature. It also requires a lot of parental investment (in terms of time, energy, calories, etc.) and means that we would have to wait a long time between offspring if each one had to independent before the mother could have another.   We don’t do that, tending to have a shorter interval between subsequent births (the inter-birth interval, or IBI) than other great apes. The long period of childhood dependence and the short IBI mean that, as a species, humans tend to have multiple, dependent offspring of different ages at the same time. Speaking as a parent of multiple, dependent offspring of different ages, I can tell you that this is often no walk in the park. This peculiar human strategy has a lot of costs.

Understanding when, how, and why this distinctly human reproductive strategy developed is a great evolutionary question. Reducing the IBI increases the potential fertility of human populations, but also creates new demands on the energies of parents and families. Human families today often offset those extra energy demands by getting help (evolutionary anthropologists call it “cooperative breeding”). A new paper in the Journal of Human Evolution titled “When Mothers Need Others” by Karen Kramer and Erik Otárola-Castillo tries to further our understanding of where cooperative breeding comes from, using an “exploratory model” to try to understand the selective pressures associated with the evolution of human-like patterns of reproduction and child-rearing. The goal of the paper “is to develop a model to predict those life history transitions where selective pressure would have been strongest for cooperative childrearing” (pg. 5).

Kramer and Otárola-Castillo call their model the “Force of Dependence Model.” Their model is a simple one, calculating “the net cost of offspring as a function of dispersal age, birth intervals and juvenile dependence” as a 3-dimensional surface (Supplementary Online Material from Kramer and Otárola-Castillo 2015). The authors use several different combinations of settings to represent a range of conditions from “ancestral” (juvenile independence at age 10, IBI of 6 years, and a dispersal age of 14) to “most derived” (juvenile independence at age 20, IBI of 3 years, and a dispersal age of 20). Their graphs show that “net costs” within a domestic group (a mother and her offspring) are lower when offspring are spaced further apart and become independent at a younger age. When offspring hang around past the age of juvenile independence, there is a net benefit to the domestic group as their productive capacities can be used to offset the drain of their younger siblings. The authors find that the strain points – where selective pressures for assistance would be greatest – occur in domestic groups with the most derived set of characteristics: late juvenile independence and a low IBI (lots of children who remain dependent for a long time).

As I understand it, the “net cost” in this model more-or-less mirrors the dependency ratio (the ratio of consumers to producers) of a domestic group or family, something anthropologists have been interested in understanding for a long time. The higher the ratio of consumers to producers, the higher the dependency ratio, and the higher the “cost” to each producer supporting the family. The dependency ratio changes through the lifespan of a family in a patterned way: every domestic group that has children goes through a “pinch” period when the dependency ratio is highest, and the pinch period logically corresponds to the time when there are a lot of dependent offspring. As I wrote in my 2013 paper in the Journal of Anthropological Archaeology (“Subsistence Economics, Family Size, and the Emergence of Social Complexity in Hunter-Gatherer Systems in Eastern North America,” available here):

“the duration and amplitude of the ‘pinch’ is affected by the rapidity of the addition of offspring and how quickly those offspring turn from consumers into producers. The rapidity of addition of offspring will depend on factors such as fertility, infant and childhood mortality, and the number of wives. The productive potential of children will be affected by the presence and distribution of resources that can be procured by children and the foraging strategies that are employed to exploit those resources” (White 2013:128).

The main part of that paper used an agent-based model (ABM) to try to understand how the distribution of family size changes when the age at which children become producers (the “age of juvenile independence” in Kramer and Otárola-Castillo’s model) decreases and there is an incentive for polygynous marriage. In addition to the ABM, I used a simple spreadsheet model to show how the dependency ratio changed through the course of the developmental cycle of an individual family in cases where the age at production was low (8 years old) and where it was high (14 years old). In this simple model, I used an IBI of 3, a dispersal age of 16 for females and 20 for males, and a female reproductive period spanning ages 20-35 years (giving a total fertility of 6 offspring).

The figure below compares Kramer and Otárola-Castillo’s graphs from their cases with early and late juvenile independence (holding IBI at 3 and dispersal age at 14) with my data on changes in dependency ratio through the developmental cycle in cases with a single reproducing female and an age at production of 8 (top) and 14 (bottom).   My model data are the same as in my 2013 paper (Figure 5), but I have re-graphed them to make comparison with Kramer and Otárola-Castillo’s figure easier. I have redrawn the graphs from Kramer and Otárola’s Figure 1 (third graphs from the left, top and bottom rows). The dotted lines on the graphs of my results indicate a dependency ratio of 1.75, which is what I have generally used in my modeling efforts as a “typical” dependency ratio among hunter-gatherers (following Binford 2001:230).

My results showed the same pattern as Kramer and Otárola-Castillo’s: the peak of the “pinch” comes earlier and is less severe when children become producers at an earlier age. Even though our models have some differences (and some of the values of the parameters were different), the correspondence in results is notable. Compare, for example, when the amplitude of the “pinch” (peak dependency ratio in my results, greatest net cost in Kramer and Otárola-Castillo’s results; marked by stars) is greatest and the differences in amplitude between the early and late ages of juvenile contributions to subsistence.

The correspondence between my results and Kramer and Otárola-Castillo’s is unsurprising. The idea that the dependency ratio of a domestic group changes through the course of its developmental cycle in a somewhat predictable way is not new (and the idea that the “pinch” comes when you have lots of little kids running around at the same time won’t come as a revelation to anyone who has multiple children). This is a phenomenon that has been studied for decades (e.g., Chayanov 1966; Donham 1999; Fortes 1958; Goody 1958) and recognized as a key aspect of how hunter-gatherers organize themselves (Binford 2001:229).

So where does this kind of work put us in terms of understanding the evolution of human reproduction, society, and family life? I think it primarily puts us in a spot where we’re asking some good questions. Going back to the issue of the origins of monogamous pair-bonding (which I touched on briefly in this post about birth assistance and this post about australopithecine sexual dimorphism), having a two person (male-female) unit forming the core of a domestic group would have a mitigating effect on the strain caused by a decrease in IBI (i.e., you’d be adding another producer into the equation). If the appearance of male-female pair-bonding was associated with a sexual division of labor (which is I think what most of us would hypothesize), males and females would presumably be focused on procuring somewhat different sets of subsistence resources. Offspring could be largely “independent” with regards to some of those resources but not to others – think about the difference between collecting berries and running down large game. A sexual division of labor and an environment where relatively young children could make some contribution to their own subsistence (even if that contribution does not include the full range of resources that are exploited) would go a long way toward easing the “pinch” that comes from having more children spaced closer together.

When does this happen in human evolution? Of course that’s a tough thing to get at directly. I think if you took a poll, the winner would probably be “around the time our genus emerges” or “with Homo erectus.” An increase in total fertility (coincident with a lowering of the IBI) would help explain the population growth that must have been part of the dispersal of our species out of Africa prior to 1.8 million years ago. It would also fit nicely with the evidence for an increased exploitation of animal resources around that same time. Maybe Glynn Isaac was right all along to propose the emergence of human-like central place foraging with home bases and a sexual division of labor at the beginning of the Lower Paleolithic?

But what if monogamous pair-bonding and a sexual division of labor appeared much earlier – with australopithecines or even some pre-australopithecine like Ardipithecus? If those things came along with bipedal locomotion, would a decreased IBI and increased fertility have followed automatically? Maybe not. Perhaps those earlier hominids just didn’t have the wherewithal to exploit their environments like later hominids did – perhaps the diversity of the resource base they could exploit wasn’t great enough to really leverage a sexual division of labor until animal products became readily attainable. That may have required a suite of anatomical adaptations for daytime exhaustion hunting (loss of body hair, skin pigmentation, greater body size, stiffer foot) and cognitive/behavioral adaptations for making and using stone tools to process carcasses. The date of the “earliest” proposed use of stone tools continues to be pushed back (now it’s at 3.3. million years ago), but as far as I know the density of stone tools and butchered animal bones that appears at about 1.8 million years ago is unlike anything that precedes it.

More modeling work will be required to really understand how changes in the dependency ratio might have articulated with changes in reproductive, social, and technological behaviors deep in human prehistory. In order to understand what changes in reproduction might have meant in terms of social interactions, however, we’ll need a different grade of model than that used by Kramer and Otárola-Castillo. Of course I’m going to say that complex systems modeling is the way to go on this: it will let us get past the limitations of deterministic inputs and help us understand how constraints, costs, and interactions would have played out within a society. In order for “others” to help with raising and provisioning multiple dependents, those others had to have existed within these small-scale hominid societies and (again, speaking as someone involved in raising multiple small kids) there wouldn't have been some inexhaustible Plio-Pleistocene babysitting pool of “others” out there just waiting to step in and provide extra calories for a few years. A different kind of modeling effort with broader scope will let us get at the group- and society-level contexts in which family-level changes in child-bearing and child-rearing would have played out. Stay tuned.

References

Binford, Lewis R. 2001. Constructing Frames of Reference: An Analytical Method for Archaeological Theory Building Using Hunter-Gatherer and Environmental Data Sets. University of California Press, Berkeley.

Chayanov, A. V. 1966. A. V. Chayanov on the Theory of Peasant Economy. University of Wisconsin Press, Madison.

Donham, Donald L. 1999. History, power, ideology: Central issues in Marxism and anthropology. University of California Press, Berkeley.

Fortes, Meyer. 1958. Introduction. In The Developmental Cycle in Domestic Groups, edited by Jack Goody, pp. 1-14. Cambridge Papers in Social Anthropology. Cambridge University Press, London.

Goody, Jack. 1958. The Fission of Domestic Groups among the LoDagaba. In The Developmental Cycle in Domestic Groups, edited by Jack Goody, pp. 53-91. Cambridge Papers in Social Anthropology. Cambridge University Press, London.

Kramer, K., & Otárola-Castillo, E. (2015). When mothers need others: The impact of hominin life history evolution on cooperative breeding Journal of Human Evolution DOI: 10.1016/j.jhevol.2015.01.009

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Australopithecine Sexual Dimorphism: What's Love Got to Do With It?

5/2/2015

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Last week I posted a short piece wondering aloud if we are safe in assuming that female australopithecines, rather than males, were the ones giving assistance to other australopithecines during birth. The response of one of my friends on Twitter was that "Sexual selection says they should've been too busy getting busy to care." Like the ambiguity in the student paper that prompted me to ask the male/female birth assistance question in the first place, I'm not exactly sure of the intent of the response. Was it to use the notion of sexual selection to dismiss the idea that males could have played a beneficial role in australopithecine births? Or was it to poke fun at how much weight we give sexual selection?

Sexual selection is selection (differential reproduction) that occurs when some individuals reproduce more than others because they are better at securing mates, rather than because of interaction with the environment (as in natural selection. Charles Darwin coined the term and explained in On the Origin of Species (1859:88). Sexual selection, he wrote,

"depends, not on a struggle for existence, but on a struggle between the males for possession of the females; the result is not death to the unsuccessful competitor, but few or no offspring. Sexual selection is, therefore, less rigorous than natural selection. Generally, the most vigorous males, those which are best fitted for their places in nature, will leave most progeny. But in many cases, victory will depend not on general vigour, but on having special weapons, confined to the male sex. . . . The war is, perhaps, severest between the males of polygamous animals, and these seem oftenest provided with special weapons."

How important was sexual selection among australopithecines? We have traditionally looked at two aspects of sexual dimorphism (differences between males and females) to evaluate the degree of male-male competition in primates: canine size and body size. If sexual selection was important among australopithecines (as it is chimpanzees and gorillas, our two closest living relatives) we would expect to see males with significantly larger canines and of significantly greater body size than females. The fossil record isn't as clear on these things as you might think.

Canine Size

The drawing below shows maxillary dentitions from a chimpanzee, an Australopithecus afarensis (ca. 3.9-2.9 MYA), and a modern human. I think the original drawing is from the (1981) book Lucy: The Beginnings of Humankind by Donald Johanson and Maitland Edey. The difference in the relative sizes of the canines (indicated with red arrows) is obvious. Chimpanzees (especially males) have large canines. The space between the canine and the incisors (called a diastema) is there to accommodate the opposing canine when the jaws are closed. The canines of modern humans barely protrude at all, and there is no diastema. The canines of australopithecines are larger than those of modern humans, but smaller than those of chimps. They protrude slightly, and there is a small diastema.

The australopithecine specimen in the drawing is a reconstruction of the palate of Lucy (AL 200-1), traditionally interpreted as the remains of a female (but see below). So that single specimen alone tells us nothing about male canine size and nothing about sexual dimorphism in canine size. Studies looking at samples of australopithecines have come to different conclusions about the degree of sexual dimorphism in the canines. A 1997 paper by J.Michael Plavcana and Carel P. van Schaik concluded that:

"Estimates of canine dimorphism, relative canine size, and body weight dimorphism in australopithecines provide little definitive information about male–male competition or mating systems. Dimorphism of Australopithecus africanus and Australopithecus robustus can be reconciled with a mating system characterized by low-intensity male–male competition. The pattern of dimorphism and relative canine size in Australopithecus afarensis and A. robustus provides contradictory evidence about mating systems and male–male competition."

This 2005 paper by Sang-Hee Lee paper concluded (based on a resampling method that wasn't dependent on sex estimates) that canine sexual dimorphism in Australopithecus afarensis was comparable to that seen in chimpanzees.

The canines of Ardipithecus ramidus (ca. 4.4 MYA) are smaller than those of chimpanzees but larger than those of modern humans. The image below shows a comparison of a modern human (left), Ardipithecus (middle), and chimpanzee (right) (source). The teeth in the image belong to "Ardi," the relatively complete skeleton of Ardipithecus ramidus discovered in 1994 and published in 2009. That skeleton has been interpreted as the remains of a female. An analysis of other Aridipithecus ramidus teeth (Suwa et al. 2009) concluded that male and female canine teeth were of similar size.

If Ardipithecus is a hominid and the dental remains have been interpreted correctly, it suggests that males early in our lineage did not have large canines, presumably indicating that they were not vigorously competing with one another for mates (i.e., sexual selection was relatively unimportant). It would also suggests that the LCA was unlike chimpanzees in many ways (e.g., perhaps an arboreal biped with a flexible back, mobile wrist, and generalized dentition rather than a knuckle-walking quadruped), making the chimpanzee overall a poor model of the LCA and therefore a poor model upon which to base explanations of evolutionary change in our lineage.

The single published skull from Sahelanthropus, a possible hominid from about 7 MYA, has been interpreted as that of a male with a relatively small canine. I don't claim to have read the Sahelanthropus studies in detail, but I'm dubious that you can accurately estimate sex for a single skull from species about which so little else is known. If the skull is that of a male, whether or not it's a hominid, it would be consistent with a low level of sexual selection in late Miocene apes. If it's a female it doesn't tell us much about competition between males.

So the canine picture is a confusing one. The canines of australopithecines sure don't look large to me (compared to chimpanzees), but at least some studies suggest a relatively high degree of dimorphism among some australopithecines. If either Ardipithecus or Sahelanthropus was a hominid with a low degree of sexual dimorphism of the canines (suggesting low male-male competition), greater canine sexual dimorphism among australopithecines would suggest an increase in sexual selection during the Pliocene. If the LCA was more like a chimpanzee, however, sexual selection may have decreased during the Pliocene.

Body Size

The body size picture is also confusing. You can find a paper to support whatever you want, from a high degree of sexual dimorphism in body size (like gorillas) to a low degree of sexual dimorphism (like modern humans). When I talk to my Human Origins class about it, I just tell them what sexual dimorphism is and why we would like to know about it, and then confess that I can't make up my mind what the best answer is at the moment.

A paper published last week came down on the side of low sexual dimorphism in body size. The authors, Philip Reno and Owen Lovejoy, conclude that:

"The relatively stable size patterns observed between Ardipithecus and Australopithecus suggest there was not strong selection for greater male body size that would result from a reproductive strategy arising from increased individual male reproductive success via inter-individual aggression. In fact, the reduction in canine dimorphism with feminization in the male would argue for reduced “agonistic” behaviors (Lovejoy, 2009). This is particularly so given the strong association between canine dimorphism and reproductive behavior in anthropoids (Plavcan, 2012b) and the lack of a dramatic dietary shift associated with canine modification in early hominids (Suwa et al., 2009)."

This is not a new argument from Lovejoy, who has been hypothesizing the presence of monogamous reproductive strategies among early hominids for decades.

What's Love Got to Do With It?

We've got a lot to learn about australopithecine social organization and the lack of clarity about sexual dimorphism does not help. In my post about whether birth assistance was a gendered activity, I reasoned that it would be more likely that males would be involved in birth assistance if males and females were pair-bonded. In that circumstance, paternity would be more-or-less certain, and male behavior that increased the success of reproduction would be selected for. Overall, I like the anatomical evidence for a relatively low level of sexual selection among australopithecines, consistent with low levels of male-male competition. Without being able to accurately determine the sex of australopithecine fossils, however, its hard to have a lot of confidence. If Lovejoy is right about Ardipithecus, male-female pair-bonding was already present in the ancestors of australopithecines (could it even have been typical of many apes in the late Miocene?). If the LCA was more like a chimpanzee, however, sexual selection may have been strong at the time of the divergence of the chimpanzee and human lineages.

Even if australopithecines had a monogamous, pair-bonded mating system, however, that doesn't mean there was anything like culture attached to it. It may have just been part of a hard-wired biological adaptation, one that emerged along with bipedalism because it made evolutionary sense. Along with certainty of paternity would come greater paternal investment in offspring, presumably resulting in a higher survival rate (hence being selected for). The low/moderate amounts of sexual dimorphism in body size could be accounted for by the positive relationship between body size and energy efficiency during bipedal locomotion: males provisioning females and their offspring would have to travel longer distances than females, selecting for larger body sizes among males (but not larger canines) (see Daniel Lieberman's book The Story of the Human Body). In this scenario, "love" would be related to sexual dimorphism not because of male-male competition but because bigger males would be better providers.

Convinced? I'm not (either way). But it's worth thinking about.

Reno PL, & Lovejoy CO (2015). From Lucy to Kadanuumuu: balanced analyses of Australopithecus afarensis assemblages confirm only moderate skeletal dimorphism. PeerJ, 3 PMID: 25945314

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Was Birth Assistance Among Early Hominids a Gendered Activity?

4/25/2015

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Depiction of male and female Australopithecines at the American Museum of Natural History.

I've always like Karen Rosenberg and Wenda Trevathan's (2002) paper "Birth, Obstetrics, and Human Evolution" (available here). It does a nice job of exploring the social implications of anatomical changes related to the emergence of bipedalism, focusing on how the shape of the pelvis in australopithecines would have complicated birth and transformed delivery from a solitary experience into one that often required assistance. I used a condensed version of the article (Scientific American 13:80-85, 2003) in my 200-level Human Origins class: it really helps students see how you can make connections between fossils and behaviors and how one aspect of human evolution can have implications for others.

While I was reading one of the student papers from that class this semester, I started to question the model I had in my head of australopithecine females assisting each other in birth. The student wrote something that seemed to imply (intentionally or not - I'm not sure) that males were the ones giving assistance at birth. It struck me as odd, which made me ask myself why it should strike me as odd: why did I assume females and not males?

I don't think Rosenberg and Trevathan ever specify that females would have been the ones providing assistance to other females, but they use the term "midwifery" several times in their papers. Though not technically defined today as excluding males, the term "midwife" carries a lot of history that associates it very closely with females. This is the etymology as provided by Wikipedia:

"The term midwife is derived from Middle English: midwyf literally "with-woman", i.e. "the woman with (the mother at birth), the woman assisting" (in Middle English and Old English, mid = "with", wīf = "woman")."

Based on a quick perusal of some of the web resources that pop up first (e.g.,this, this, and this) the idea of the ancient origins of the association between females and birth assistance is widespread. I have no reason to doubt that this is correct: I would presume a strong female bias in birth assistance could be amply demonstrated both historically and ethnographically.

So should we assume that females were also providing birth assistance among early hominids?

Maybe not.

It seems clear that our modern conceptions of who should provide assistance at birth are culture-bound. By "culture-bound" I mean connected to other shared, leaned aspects of human societies, behaviors, and symbolic systems. I don't think I'll get an argument if I state that there is zero evidence for anything like human culture among australopithecines. So what happens to our gendered conceptions of birth assistance if you remove all or most of their cultural underpinnings? Would birth assistance still be performed primarily by females?

For the sake of argument, consider how selection might act to reinforce the behavior of males assisting females during birth. If labor and delivery are dangerous for both the female and the neonate, any assistance a male mate can provide increases the chances his genes will be passed on. This would be true in a situation of stable male-female pair bonding, as pair-bonding decreases the uncertainty of paternity. The inclination of males to provide effective assistance during birth would be selected for if pair-bonding was present and birth was dangerous.

If we assume that pair-bonding among australopithecines would not have been the same thing as "marriage" (a human cultural behavior), why do we assume that australopithecine birth assistance would be the same thing as "midwifery"? Our historical and ethnographic record of what humans do now really only gets us so far in addressing questions like this: the universality of a cultural practice among modern humans does not necessarily mean it always existed in the same form deep into the past.

Rosenberg, K., & Trevathan, W. (2002). Birth, obstetrics and human evolution BJOG: An International Journal of Obstetrics and Gynaecology, 109 (11), 1199-1206 DOI: 10.1046/j.1471-0528.2002.00010.x

Update (5/3/2015): The response of one of my friends on Twitter to this post was that "Sexual selection says they should've been too busy getting busy to care." I wrote this quick post taking an informal look at ideas about sexual dimorphism and sexual selection among australopithecines. It looks to me like the jury is still out, as there's a lot of conflicting information about the degree of sexual dimorphism in the two criteria we look at most often in primates: canine size and body size.

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Fetal Head Molding and Obstetrics in Late Pleistocene Humans

3/15/2015

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Preface: This post presents some work I did as a graduate student at the University of Michigan in 2007. It was a poster for a class called "Evolution of the Genus Homo," taught by Milford Wolpoff. I chose the topic because of my interest in the culture, biology, and social organization of Middle/Late Paleolithic humans (see discussion of my 2014 SAA paper here and here, and my 2015 AJPA paper here). I had hoped to develop this into a paper either alone or with a collaborator, but I have never found the time to follow through. As the information I collected ages and I begin to focus on moving to a new job that will require a lot of attention up front to the archaeology of the southeastern United States, it seems less and less likely that I'll ever get around to turning this into a paper. So I'm going to put my analysis from the poster out there "as is" and hope it useful to someone. If you read this and think it's an interesting idea or one that you'd like to pursue, let me know!

I apologize for the state of the bibliography: there are some formatting errors that I will correct when I have the time.

Fetal Head Molding and Obstetrics in Late Pleistocene Humans

Figure 1. Illustration of changes in head shape that occur during birth (from A.D.A.M).

Introduction

This study compares available data from fetal and neonatal crania from the Late Pleistocene to the mechanics of fetal head molding during birth in recent humans.   The small number of fetal and neonatal remains dating to the Late Pleistocene offer an opportunity to simultaneously explore issues of obstetrics, selection, and early brain growth. Most treatments of birth and obstetrics in Pleistocene humans have focused on pelvic anatomy (e.g., Rak and Arensburg 1987; Rosenberg 1998; Rosenberg and Trevathan 2002; Trinkhaus 1984). Studies of childhood growth and development after birth are limited mainly by the dearth of sub-adult skeletons, particularly those that pre-date Neandertals (see Anton 2002; Dean et al. 1986; Minugh-Purvis 1988, 2002; Nelson and Thompson 2002; Stringer et al. 1990; Tellier 1998; Trinkhaus and Tompkins 1990).   Fetal and neonatal remains, from Neandertals and other Late Pleistocene humans, have been described but have not been the subject of detailed, hypothesis-based research.

Deformation (molding) of the fetal cranium is an important part of successful birth in recent humans. This study examines the hypothesis that thickness of fetal cranial bone would have been an impediment to successful birth in Neandertals and other Late Pleistocene humans. Investigating the possible role of fetal head molding in Pleistocene obstetrics may help shed light on both anatomical trends in human cranium (i.e., the emergence of "modern" cranial morphology) and demographic variables and population genetics that may underlay the spread of anatomical "modernity."   Mortality and trauma during childbirth, acting on the mother and/or the fetus, would be an important selective force.

Two aspects of fetal head molding are emphasized: cranial vault thickness and head dimensions.    Vault thickness affects the response of the cranium to pressure during birth. Head size and shape affect both the degree of molding that is required for the fetal head to pass through the birth canal and the distribution of forces on the fetal cranium.

Hypothesis: Thick fetal cranial bone in Late Pleistocene archaic humans would have caused difficulties during childbirth (relative to recent humans) by inhibiting head molding during delivery.

Assuming uniformity in the size of the birth canal between archaic and recent humans, this hypothesis has two test implications:

1) the increased thickness of Late Pleistocene fetal cranial vaults would have a significant effect on elasticity of the cranium

2) the dimensions of the fetal cranium are such that significant molding is required for delivery

In other words, fetal head molding must be shown to be both necessary (by the dimensions of the cranium) and significantly impeded (by the in-elasticity of the vault) in order to fail to reject the hypothesis. If either one of these test implications is rejected, then the hypothesis can be rejected.

Pleistocene Obstetrics: Previous Research

Much research focused on questions of obstetrics in Pleistocene humans have emphasized the selective constraints between locomation and birth mechanics in the pelvis (Rak and Arensburg 1987; Rosenberg 1998; Rosenberg and Trevathan 2002; Ruff 1995; Trinkhaus 1984). Based on pelvis remains, most researchers conclude that birth in Pleistocene humans was much like birth in recent humans (Rosenberg 1998; Rosenberg and Trevathan 2002). Subsequent to the description of the Kebara 2 pelvis (Rak and Arensburg 1987), most ideas about an unusually long gestation periods (Trinkhaus 1984) and rapid in utero brain growth (Dean et al. 1986) in Neandertals have been rejected (see Stringer et al. 1990:148).

While pelvic inlet size during the Pleistocene appears to be, overall, similar to modern humans, cranial capacity increased. during the Middle and Late Pleistocene. Stasis in pelvic inlet size and increase in head size produces an "obstetric dilemma" where the fetal head is larger than the birth canal. Rosenberg and Trevathan (2002:1205) state that

"Two changes could have allowed an increase in adult brain size to occur: human infants could have been born with a smaller percentage of adult brain size (resulting in greater infant helplessness) and/or there could have been an alteration of the shape of the pelvis concomitant with a change in the mechanism of birth."

There is a third possibility: fetal head molding. The possible importance of fetal head molding in Neandertals is raised by similarities in both pelvic inlet size and adult cranial capacity to recent humans. Minugh-Purvis (1988:260) speculated that the thicker vault bone observed in Neandertal fetal remains would have posed a problem if delivery required a "considerable degree of head molding." The possibility was also discussed by Friedlander and Jorndan (1994).

Figure 2.

Fetal Head Molding in Recent Human Birth

In recent humans, the fetal cranium is a flexible structure that deforms during birth because of pressures between the fetal head and the cervical walls (Lapeer and Prager 2001; McPherson and Kriewall 1980a, 1980b) (Figure 2). Pressures and deformation are greatest at the sub-occipito bregmatic plane (Lapeer and Prager 2001; Rosenberg and Trevthan 2002).

During a normal labor, the parietal bones undergo the most significant changes in shape, being compressed towards each other and elongating in the axial plane (Lapeer and Prager 2001; McPherson and Kriewall 1980b). The occipital bone is relatively rigid and undergoes little change during molding (McPherson and Kriewall 1980b:18; Rosenberg and Trevathan 2002:1201). The frontal, occipital, and parietal bones interlock at the sutures after a certain limit of deformation occurs, preventing excessive molding and protecting the brain within a more rigid structure (McPherson and Kriewall 1980a:15).

The risk of excessive molding is greater in pre-term deliveries, where cranial bone is not sufficiently thick to prevent excessive molding (McPherson and Kriewall 1980a). Clinical studies have shown that excessive molding during birth (i.e., where too much deformation occurs) may be linked to psycho-neurological disorders, mental retardation, cerebral palsy, and death (see McPherson and Kriewall 1980b).

Fetal cranial bone must be thin enough to allow sufficient deformation of the cranium, but thick enough to form a rigid structure to protect the brain. Optimal thickness values would vary for different portions of the fetal cranium depending on the pressures that are exerted and the required responses to those pressures.

Parietal Thickness, Span, and Deformation Under Load

Parietal bones grow outward from a center of ossification that later becomes the parietal eminence (Ohtsuki 1980). The bones are thickest at the eminence, thinning towards their margins (McPherson and Kriewall 1980b). Ohtsuki (1977) reported a mean thickness of 0.54 +/- 0.13 mm for term (9-10 month) fetal parietal bones at the center of ossification and a thickness of 0.40 +/- 0.10 for term fetal frontal bones at the center of ossification (n = 10). McPherson and Kriewall (1980a:10) reported term fetal parietal bones that varied in mean thickness from 0.71-0.86 mm.

In their analysis of the mechanical properties of fetal parietal bone, McPherson and Kriewall (1980a:11) found that differences in thickness and the orientation of the bone fibers affected the elastic modulus (the resistance to deformation when a load is applied). Thicker cranial bone requires more force to deform. Figure 3 shows the relationship between thickness and elastic modulus in the data supplied by McPherson and Kriewall (1980a:10,13), using only the parietal bones with fibers orientated parallel.

Using the formulae provided by McPherson and Kriewall (1980:11), we can use the estimates of elastic modulus to estimate the loads that would be required to bend segments of bone of varying length and thicknesses (Figures 4 and 5). Other things being equal, longer "beams" of bone require less force to bend, while thicker "beams" require more. To have the same resistance to bending force, a longer "beam" must be thicker.

Figure 3. Thickness of fetal cranial bone plotted against elastic modulus (data from McPherson and Kriewall 1980a). The regression (R2 = 0.78) is: 4.13 + 2.86(log of thickness in mm)

Figure 4. Plot of force required to cause a deflection of 1 mm in "beams" of bone of varying thickness (assuming a beam length of 75 mm - approximately that of a modern human term fetus). While the absolute values of these calculations may not be accurate (parietal bones vary in thickness in cross-section and do not behave simply as "beams") the calculations show that the resistance to force changes dramatically when thickness increases from 1 mm to 2 mm.

Figure 5. Plot of force required to cause a deflection of 1 mm in "beams" of bone of varying length (assuming a beam thickness of 1 mm).

Fetal Vault Thickness, Dimensions, and Molding in Late Pleistocene Homo

The Late Pleistocene fossil record contains numerous remains from sub-adult specimens. Of interest here are those remains that preserve portions of the cranial vault, particularly the frontal and parietal bones. Fetal and neonatal remains of Neandertals have been recovered from La Ferrassie (Heim 1982) and Hortus (Lumley-Woodyear 1973). Rremains of two Neandertals less than about a year old have been reported from Shanidar (Trinkhaus 1983) and Krapina (Minugh-Purvis 1988). Neonatal remains attributed to anatomically modern Homo sapiens have been reported from Cro-Magnon (Minugh-Purvis 1988), Qafzeh (Tillier 1999), and Abri Patuad (Minugh-Purvis 1988). Krapina is the earliest site, dating to the late Riss/early Wurm (Wolpoff 1999). La Ferrassie, Shanidar, Qafzeh, and Hortus date to Wurm I/Wurm II. Abri Pataud and Cro-Magnon date to Wurm III/IV (Wolpoff 1999).

Vault Thickness

Data on vault thickness at the parietal and frontal eminences are available for six fetal/neonate skeletons and three young (<1 year) infants from the Late Pleistocene.

Figure 6. Top: Drawing of Neandertal neonatal parietal from Hortus 1b (adapted from Lumley-Woodyear 1973). Bottom: Neandertal fetal and newborn frontal bone fragments from La Ferrassie compared to frontals from recent humans (adapted from Heim 1982).

Figure 7.

The thickness of the frontal and parietal bones in this sample contrasts with the data from the modern sample provided by Ohtsuki (1977) (Figure 7), outside the 2 sigma range of his means for term fetuses. If the Late Pleistocene fetal and neonate remains are aged accurately, fetal parietal bone was generally 1.5 to 2 times thicker than that of modern humans.

Considerably more force would be required to deform these bones, assuming the geometry of the bones was otherwise equivalent (see below).

Test prediction 1 is supported: differences in fetal cranial vault thickness are sufficient to affect molding of the cranium.

Fetal Head Dimensions

The limited data available on very young Late Pleistocene individuals suggests that some aspects of fetal head geometry may have differed from that of more recent humans (Minugh-Purvis 2002; Stringer et al. 1990). Bregma-lambda distance appears to have been shorter in Neandertals than in recent humans throughout life (see Minugh-Purvis 2002:488-489; Gunz and Havarti 2007; Harvarti 2003; Trinkhaus 1983:371). In mature Neandertals, the shorter distance is associated with a lower position of bregma (see Harvarti 2003)

Figure 8.

A shorter bregma-lambda distance would reduce the cross-section of the fetal cranium in a dimension that is key to the necessity for fetal head molding. It appears that this distance may have been about 10 mm less in Neandertals at the time of birth relative to recent humans: perhaps 80 mm rather than 90 mm (see Minugh-Purvis 2002). A difference of ca. 10-12% in the bregma-lambda chord would be sufficient to account for a 3-7% reduction in the sub-occipito-bregmatic diameter (SOBD). Assuming equivalence in other dimensions of the head and pelvic inlet, this difference alone would significantly lessen the degree of fetal head molding that would be required for successful delivery.

Test prediction 2 is not supported: the dimensions of the fetal cranium are such that significant molding was probably not required for delivery.

Conclusions

Significant fetal head molding was probably not critical to successful Neanderthal birth. While thicker cranial bone would have reduced elasticity, a smaller SOBD would have negated or lessened the need for molding during birth.

Reduction in fetal cranial thickness may not have been a reproductive advantage for "modern" humans. Rather, cranial thinness associated with an increase in the SOBD may have increased the risks to the fetus during birth (i.e., though excessive molding) while reducing or maintaining the risk to both mother and fetus (i.e., through arrested labor). In the absence of selection for thinner bone associated with a flexibility requirement, thick fetal cranial bone would have offered protection to the fetal brain during delivery. Apparent stasis in pelvic anatomy suggests that smaller, thicker fetal crania may be the ancestral condition. An increase in SOBD, perhaps reflecting some difference in fetal brain growth, would have preceded selection for thinner cranial bone in this scenario.

The fetal cranium is a complex mechanical structure. Constructing a simulation model (similar to that of Lapeer and Prager 2001) of delivery in Neanderthals is possible with the available data. This model could be used to test hypotheses about obstetrics in a more sophisticated way than is possible by calculating simple ratios of head and pelvic size.

References Cited

Anton, Susan C. 2002. Cranial growth in Homo erectus. In Human evolution through developmental change, edited by Nancy Minugh-Purvis and Kenneth J. McNamara, pp. 349-380. Baltimore: Johns Hopkins University Press.

Dean, M.C., C. B. Stringer, and T. Bromage. 1986.    Age at death of the Neanderthal child from Devil’s Tower, Gibraltar and the implications for studies of general growth and development in Neanderthals. American Journal of Physical Anthropology 70:301-309.

Friedlander, N. J., and D. K. Jordan. 1994. Obstetric implications of Neanderthal robusticity and bone density. Human Evolution 9:331-342.

Gunz, Philipp, and Katerina Havarti. 2007.   The Neanderthal “chignon”: Variation, integration, and homology. Journal of Human Evolution 52:262-274.

Havarti, Katerina. 2003. The Neanderthal taxonomic position: Models of intra- and inter-specific craniofacial variation. Journal of Human Evolution 44:107-132.

Heim, Jean-Louis. 1982. Les enfants nJandertaliens de La Ferrassie. Paris, Masson.

Lapeer, R.J., and R.W. Prager. 2001. Fetal head moulding: Finite element analysis of a fetal skull subjected to uterine pressures during the first stage of labour. Journal of Biomechanics 34:1125-1133.

Lumley-Woodyear, Marie-Antionette de. 1973.    AntenJanderthaliens et NJandertaliens du bassin Mediterraneen occidental europen. Etudes Quaternaires. MJmoire 2, Marseille, UniversitJ de Provence.

McPherson, Gregg K., and Timothy J. Kriewall. 1980a. The elastic modulus of fetal cranial bone: A first step towards an understanding of the biomechanics of fetal head molding. Journal of Biomechanics 13:9-16.

McPherson, Gregg K., and Timothy J. Kriewall. 1980b. Fetal head molding: An investigation utilizing a finite element model of the fetal parietal bone. Journal of Biomechanics 13(1):17-26.

Minugh-Purvis, Nancy. 1988. Patterns of craniofacial growth and development in Upper Pleistocene hominids. PhD dissertation, University of Pennsylvania.

Minugh-Purvis, Nancy. 2002.    Heterochronic change in the neurocranium and the emergence of modern humans. In Human evolution through developmental change, edited by Nancy Minugh-Purvis and Kenneth J. McNamara, pp. 479-498. Baltimore: Johns Hopkins University Press.

Nelson, Andrew J., and Jennifer L. Thompson. 2002.   Adolescent postcranial growth in Homo neanderthalensis. In Human evolution through developmental change, edited by Nancy Minugh-Purvis and Kenneth J. McNamara, pp. 442-463. Baltimore: Johns Hopkins University Press.

Ohtsuki, Fumio. 1977.    Developmental changes of the cranial bone thickness in the human fetal period. American Journal of Physical Anthropology 46:141-154.

Rak, Y., and B. Arensburg. 1987.    Kebara 2 Neandertal pelvis: First look at a complete inlet. American Journal of Physical Anthropology 73:227-231.

Roche, A. F. 1953.    Increase in cranial thickness during growth. Human Biology 25(2):81-92.

Rosenberg, Karen R. 1992.   The evolution of modern human childbirth. Yearbook of Physical Anthropology 35:89-124

Rosenberg, Karen R. 1998. Morphological variation in west Asian postcrania. In Neandertals and modern humans in western Asia, edited by Takeru Akazawa, Kenichi Aoki, and Ofer Bar-Yosef, pp. 367-379. Plenum, New York.

Rosenberg, Karen, and Wenda Trevathan. 2002.    Birth, obstetrics and human evolution. BJOG: an International Journal of Obstetrics and Gynaecology 109:1199-1206.

Ruff, Christopher B. 1995.   Biomechanics of the hip and birth in early Homo. American Journal of Physical Anthropology 98:527-574.

Stringer, Christopher B., M. Chistopher Dean, and Robert D. Martin. 1990.    A comparative study of cranial and dental development within a recent British samples and among Neandertals. In Primate life history and evolution, edited by C. Jean DeRousseau, pp. 115-152. New York: Wiley-Liss.

Tillier, Anne-Marie. 1998. Onotogenetic variation in Late Pleistocene Homo sapiens from the Near East. In Neandertals and modern humans in western Asia, edited by Takeru Akazawa, Kenichi Aoki, and Ofer Bar-Yosef, pp. 381-389. Plenum, New York.

Tillier, Anne-Marie. 1999. Les enfants mousteriens de Qafzeh: Interpretation phylogenetique et paleoauxologique. Cahiers de Paleoanthropologie. Paris, CNRS Editions.

Trinkhaus, E. 1983. The Shanidar Neanderthals. New York: Academic Press.

Trinkhaus, E. 1984    Neandertal pubic morpohology and gestation length. Current Anthropology 25:509-514.

Trinkhaus, Erik, and Robert L. Tompkins. 1990. The Neandertal life cycle: The possibility, probability, and perceptibility of contrasts with recent humans. In Primate Life History and Evolution, edited by C. Jean DeRousseau, pp. 153-180. New York: Wiley-Liss.

Young, Richard W. 1957. Postnatal growth of the frontal and parietal bones in white males. American Journal of Physical Anthropology 15:367-386.

Wolpoff, Milford H. 1999.    Paleoanthropology. 2nd edition. Boston: McGraw-Hill.

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Evolution, "Devolution," and the Incredible Shrinking of Humanity: Why Creationists Love Giants

1/23/2015

9 Comments

I'm not sure what the origin of this drawing is, but I got it from biblelandstudios.com. And by making that single attribution I have exceeded the scholarship standards of most pieces of "evidence" for giants that circulate on the internet.

When I started writing blog posts examining the evidence for a so-called “race” of giants, several people asked me about the apparent connection between the giants renaissance and creationism. My answer was simple: creationists feel that evidence of giants would be proof that the Bible was true and evolution was not. As we are often reminded, some translations of Genesis 6:4 say that “there were giants in the earth in those days.” The existence of giants, therefore, would be consistent with a Bible that is literally true. And if the Bible is true, then evolution is false.

I still think that explanation holds water: creationists (at least some of them) see the existence of giants as a key component in their case for a literal Bible. If you can find one skeleton of an ancient human that is significantly larger than any person we know of today, you’ve proven your case: the Bible would account for that but evolutionary theory could not. That’s the main idea, anyway.

As I’ve explored the question more, however, I think I have come to a better understanding of why some creationists really love giants. While it seems clear to me in retrospect, it wasn’t obvious when I first started seriously thinking about this issue a few months ago. I’m guessing that it is probably also not obvious to many others out there who also were not raised with a creationist belief system. So I thought it would be worthwhile to write it out, as I think this provides some context for understanding some dimensions of the current fascination with giants.

The love affair that some creationists have with giants stems not only from the desire to demonstrate that a few isolated (possibly mistranslated) passages in the Old Testament are literally true, but from what is actually a more-or-less coherent theory of prehistory. Using a very broad brush, I will call this the “Biblical theory of prehistory” (BTOP). The BTOP is based on a creationist understanding of the meaning and implications of Genesis. It explains changes through time in the natural world (following a supernatural creation) as the result of a “devolutionary” process of degeneration. Here is my paraphrase of the tenets of the BTOP as I understand it (advocates of this view of the world should feel free to comment and tell me if I’m misstating something):

God’s original creation was perfect
As time has passed since creation, that original perfection has naturally degenerated
The world we see today, and the creatures in it, are less than perfect as a result of a long process of “devolution”

Giant enthusiasts applying the BTOP link together the existence of large extinct animals (that we can understand via the fossil record), the long human lifespans reported in the Old Testament, and the Biblical mentions of “giants” as in Genesis 6:4. In this case, bigger is better: humans and that existed closer to the time of creation were larger in size and closer to perfection than the humans of today. The running down of the clock since creation has resulted in humans and animals that are smaller, simpler, and farther from perfection.

Joe Taylor, author of the book Giants Against Evolution and sculptor of a 47” femur, spells it out in this interview (about 21:40 minutes in):

“They [scientists and museums] want to keep up this story that we evolved from some fish that turned into a monkey and then turned into Man. The giants just mess that whole story up. And whether they agree that these giants were fathered by angels – they can’t have that because angels are spirits, God is a spirit, demons are spirits . . . they can’t believe any of that stuff. Well then they have to attribute it to people growing larger back then. Well, wouldn’t that go against the theory of evolution? That people used to get bigger and better and more hands, more toes, more teeth and fingers? So evolutionists cannot account for giantism, so they just ignore it or destroy the information.”

There are several things of interest in that statement.

First, Taylor clearly says that things going from bigger to smaller would “go against the theory of evolution.” I had an “ah-ha” moment (or maybe it was an “oh duh” moment) when I heard him say that, because I remembered reading a similar statement expressed in Richard Dewhurst’s awful book (The Ancient Giants Who Ruled America, pg. 8):

“We are shown charts of man becoming bipedal and each “new” man being bigger and smarter than the last. This is in direct contradiction to the charts we use for every other animal we study. We have only to look at a bird and be told that it was once a dinosaur to know how false this paradigm of man’s growth is. Look at the evolution of most animals, and the record says they got smaller over time, not bigger. However, with all the modern edifices of education built on the theory of evolution and the growing stature of humanity, we can’t very well have the Smithsonian running around telling people that we have degenerated from an ancient race of giants who once ruled America, now can we?”

Once you start to look, it is easy to find examples of creationists stating that: (1) the big-to-small sequence of change is common (even universal) among animals in the fossil record; (2) that pattern is a result of degeneration or “devolution;” and (3) that pattern is the opposite of what the theory of evolution predicts.

Second, Taylor ties the presence of “more toes, more teeth and fingers” (I’m going to assume that he misspoke when he said “more hands”) of humans in the past to those humans being closer to perfection. This was another “ah-ha” moment for me because it is a clear expression of why giant enthusiasts are so uncritically fascinated with “double rows of teeth:” more teeth equals better human. It is only logical that these larger, longer-lived, more perfect humans had more teeth than us, right, because that would be more “complex.” The incredible shrinking of humanity also included losing features of our anatomy that were present when we were perfect.

(I have written numerous posts now about the “double rows of teeth” issue as it pertains to the accounts of skeletons unearthed in 19th century and early 20th century America: see my “Ancient Giants” page. There are more on the way).

In essence, the BTOP purports to challenge the theory of evolution by asking “if evolution predicts that things get bigger and more complicated over time, why do we have so many examples of things getting smaller and less complicated?” The BTOP is presented as a “devolutionary” theory, naturally opposed to an “evolutionary” theory.

Anyone familiar with modern evolutionary thinking will immediately recognize what is going on here: the BTOP is presented as counterpoint to a kind of evolutionary thinking that doesn’t really exist among scientists today. Creationists who love giants are attacking a windmill. Let me explain.

Use of the term “devolution” implies that evolution has a direction. That alone signals a fundamental misunderstanding of the tenets of evolutionary theory and the mechanisms and results of evolutionary change. The vast majority of scientists today who employ evolutionary theory as a framework for understanding the natural world probably define “evolution” as something along the lines of “a change in gene frequencies over time” or even simply “change over time.” Notice what is missing from those definitions: any notion of “progress” or “direction.” Evolution is not goal-seeking and does not strive to produce something “better.” Over large scales of time and space, evolution has produced a diverse array of plant and animal species and a natural world that is complex (in that it has many different but inter-related parts), but evolutionary theory does not specify that every plant and animal goes from “simple to complex” or “primitive to advanced” or "small to big." It doesn’t work that way and no evolutionist will tell you that it does. Do some things have bigger ancestors? Sure. Do some things have smaller ancestors? Sure. So what?

The “theory of evolution” that advocates of the BTOP are positioning themselves in opposition to is actually a 19th century conception of evolution as a “progressive” process. This view has largely gone extinct, and we should all be happy for its demise. Why? Because it had no scientific merit and was employed politically to inflict great misery on many peoples of the world.

Nineteenth century Euroamerican ideas about the “progressive” biological and social evolution of humans mixed Darwin’s ideas about “survival of the fittest” with the classification of humans based on their observable physical characteristics (skin color, hair texture, facial structure, etc.) and the technological “advancement” of their societies (savagery, barbarism, civilization). (For a taste, have a look at The Origin of Civilisation and the Primitive Condition of Man by Sir John Lubbock). Peoples and societies were ranked based on the notion that those that were more “advanced” were inherently superior. Guess which peoples came out on top of these rankings? The misapplication of Darwin’s ideas about biological natural selection to the physical and cultural variation that was apparent among living human groups provided a convenient justification for the subjugation of non-European peoples across the globe: fans of colonialism, imperialism, and slavery were fans of progressive evolution, Scientific Racism, and polygenism. So were the eugenicists. And the Nazis. Notions of “progressive” evolution were applied in political contexts, often with incredible negative and tragic outcomes.

It should go without saying, but the topic of this post makes it obvious that it doesn’t: these 19th century notions that human biological/social variation is the result of some kind of “progressive” evolution are not part of modern, mainstream evolutionary thought. There - I even put it in bold so that it's easy to see. Anyone who takes a moment to try to understand what modern evolutionary theory actually is will quickly understand what it's not.

Creationists, at least those who love giants, have apparently chosen to ignore what evolutionary theory actually is and instead wage a war against some Frankenstein 19th century notion of “progressive” evolution. Consider the following passage from creationwiki.org:

“Charles Darwin theorized that evolution was a process of getting to perfection, where Christian creationists understand that the original sin of the first man Adam has brought degeneration, disease, and essentially [devolution] into the world.”

Getting to perfection? Okey dokey then.

That’s like me trying to mount an argument against the usefulness of modern medical practice by refuting the Hippocratic theory of the four bodily humors.

People who understand what “evolution” actually means in the modern sense will spot an irony here: the BTOP is itself essentially an evolutionary theory. It is evolutionary because it recognizes that plants and animals have changed through time, and specifies mechanisms that explain patterns of change. In other words, the BTOP provides a general explanation of the way the world has changed that acknowledges that the plants and animals that are present today are not the same ones that were present earlier in prehistory.

To be clear, just because I call the BTOP a “theory” does not mean it is a scientific theory or that its advocates are scientists. The opposite is true. The BTOP is a belief system masquerading as science: in science we use theories about the world to generate expectations which can be falsified based on observations. That is not what advocates of the BTOP do. They are simply looking for evidence to support an answer that they think they already have. They say they are doing science, but in the absence of any attempt at testing or falsifying, they are most certainly not. You can say you are doing science all you want, and you can display your “evidence” in a building and call it a museum, but without some kind of attempt to determine if your answers about the world are correct or incorrect, you’re not doing science.

Joe Taylor’s 47” femur sculpture based on an anonymous letter? Not evidence.

Chris Lesley’s imagination-based “replica” skull with three rows of teeth? Not evidence.

The strategy seems to be to just keep throwing pieces of baloney at the wall until one of them sticks.

Good luck with selling that as a scientific approach to understanding the past.

The eagerness to accept, prop-up, and even manufacture any piece of “evidence” that seems to support the existence of ancient giants is consistent not with a desire to understand the world scientifically but with a desire to demonstrate a “known” (what the Bible says) by assembling evidence that supports it. There is a real lack of critical thinking here and a real reluctance to ask “what part of this idea could be wrong?” If I ask you the question “what evidence would you accept that your idea is wrong?” and you answer “there isn't any,” you’re not doing science. Read that sentence twice.

This is a broad brush essay. There is much more to talk about on this topic with regard to how the BTOP deals with human/primate fossil remains (especially those that are considered to be “large”) and the diversity of opinions about what these imaginary ancient giants actually were. Once you get past the commonality of “giants in those days” you will find little coherence or agreement among the spectrum of individuals that are spinning tales about the Nephilim, antediluvian giants, evolution/devolution, etc. Were these pre-Flood giant humans “perfection” or were they the product of corruption? Did they continue to exist after the Flood? If so, how and why? Were they natural or supernatural? How do you reconcile the chronology provided by archaeology with that of the Bible? These are all great things for giantologists to discuss amongst friends who take it as a given that giants existed because it is written in the Bible.

There is one other thread that unites these folks: the desire to sell books and DVDs.

The lack of agreement among giant enthusiasts about the particulars of the story doesn’t by itself mean that a BTOP is wrong, of course. But it does resonate with an approach that combines a great emphasis on collecting and interpreting “evidence” with a nearly complete lack of interest in testing any components of the BTOP by using that evidence. It explains why creationists love giants, but by itself does nothing to strengthen the argument that there actually were giants. For that you would need evidence and some will to evaluate that evidence in light of the expectations generated by the theory. So far I haven’t seen a speck of evidence that convinces me that there is any need for a theory other than that of evolution to account for the history of life on earth and the fossil record as it relates to human origins.

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Joe Taylor's Sculpture of a 47" Femur: What's the Story?

1/20/2015

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According to Joe Taylor, one of the biggest attractions in the Mt. Blanco Fossil Museum is his sculpture of a 47” femur and an accompanying drawing showing the immense size of the individual to whom that femur belonged. You can find pictures of Taylor and his femur sculpture all over the internet, and a photo of the two together graces the back of his book “Giants Against Evolution.”

The back cover of the book (shown in the image to the right, I think) reads:

“47 inch Human Femur

In the late 1950s, during road construction in south-east Turkey in the Euphrates Valley, many tombs containing the remains of Giants were uncovered. At two sites the leg bones were measured to be about 120 cms “47.24 inches”."

The Genesis Park website makes a similar statement:

“In the late 1950’s, during road construction in the Euphrates Valley of south-east Turkey, many tombs containing the remains of giants were uncovered. At the sites the leg bones were measured to be 120 cm (47.24 in.).”

A Google search for the phrase “In the late 1950's during road construction in south-east Turkey” returns over 400,000 results, many of which appear to be retelling the story of the femur verbatim. This is a popular story. It shows up over and over and over again on websites asserting the reality of ancient giant humans.

All told, this seems to be a pretty important piece of evidence among proponents of giants.

In this interview, Taylor says that people “see the truth” in his sculpture because it has “a believable story, and it shows them how big these people were and it explains a lot of the things we see in the earth if you account for these giant men being connected to them.”

Proof that there once existed a human with a 47” femur would, indeed, be remarkable. There is no question about that.

So one might reasonable ask what is the basis of this remarkable claim? Surely there is some compelling evidence that explains why this claim is so widely accepted and so vigorously promoted?

Prepare to be disappointed.

The entire basis for this claim appears to be an anonymous letter. Ac cording the Mt. Blanco Fossil Museum website, this is what the reported letter said:

“Dear Christian Friends, I was born and lived in the Middle East from 1938 to 1968. I was Ain-Tell and Euphrates water works Engineer and was very interested in archaeology and history and had some very interesting findings, some of which may sound unbelievable. I have brought with me a few silex arrow heads, etc., from the very battle-field where King Nebuchadnezzar and Pharo-Necho’s armies fought. And what about the giants mentioned in Genesis? In south-east Turkey in the Euphrates Valley and in Homs and at Uran-Zohra, tombs of about four meters long once existed, but now roads and other construction work has destroyed the spots. At two places, when unearthed because of construction work, the leg bones were measured about 120 cms. It sounds unbelievable. I have lived with my family at Ain-Tell for more than 14 years at the very spot where King Nebuchadnezzar had his headquarters after the battle of Charcamish, where I dug the graves of kings’ officers and found their skeletons like sponge, and when you touch them they become like white ash, with spears and silex and obsidian tools and ammunition laying by.”

As best I can tell, that’s it. That’s all of the evidence there is. That’s the story. That’s the documentation shoring up this key piece of evidence: an unsigned letter that anyone, anywhere could have written.

Is there any more to this story? In this interview it looks like there may be a longer version of the letter, but Taylor tells the same basic story: guy writes a letter to another guy about what he saw, we make a sculpture and glue it to a board. Case closed, evolution refuted.

In that same interview, Taylor asks “why isn’t it known throughout all the museums in the world . . . why don’t they talk about these giants?” His answer to his own question is that the atheists controlling museums know that proof of giants would be proof that the Bible was true.

My answer to Taylor's question is a little bit different: because your “evidence” is a sculpture based on a measurement reported in a letter that may have been a complete fabrication. I wouldn’t even try to get a refund for a gallon of sour milk with evidence as thin as what Taylor presents for this extraordinary claim, let alone try to use it to “refute the theory of evolution.”

Maybe there is something else to this story but it just hasn't been clearly presented. Please let me know if I missed something. If this is all there is you might as well just say “A guy wrote me a letter that stated evolution is wrong . . . let’s build a museum.”

In both of the interviews I watched, Taylor said the bone was discovered in Egypt rather than Turkey. One of the ads on the museum website (scroll down on the page) says the bone was “found in Egypt by road construction engineers in the 1960s." I know that details can be inconvenient, but you would think that we could keep at least two of them straight in this instance since there are really only three: (1) Turkey (or Egypt?), (2) 1950s (or 1960s?), (3) 47” leg bone. At least we've got the 47" leg bone.

But wait, the alleged letter actually says "the leg bones were measured about 120 cms." This could be interpreted to mean that both the bones of the leg (tibia and femur) together measured 120 cm. This would still be a tall person, but not a 15' giant. So I guess we're not even really clear on the 47" femur.

I spent a few minutes trying to find places called “Homs” and “Uran-Zohra” in Turkey and couldn’t. I’m not ready to claim they don’t exist since I didn't search thoroughly, but it is notable that what popped up right away searching on these words were re-posts of the same verbatim giant account. There is a Homs in western Syria, but (best I can tell) it isn't in the Euphrates drainage basin? The Euphrates definitely isn't in Egypt. Where was the bone supposedly found? Turkey? Egypt? Syria? Narnia?

I’m not exactly sure what all of this is proof of, but it’s certainly not proof of the existence of giants.

This tale is my new frontrunner in the category of “most bang for the buck” in terms of the ratio of its perceived importance among giant enthusiasts to the strength of evidence presented. At least the fascination with the Delevan skeletons is based on a newspaper account. And at least Jim Vieira actually called someone on the phone to discuss the story of Charles Huntington’s “eyewitness” account. All we have here is an opportunity to buy a $450 cast of a giant femur that was reportedly seen in Egypyt, or Turkey, or somewhere over there somewhere in the 1950s. Or maybe the 1960s. By somebody.

I wish I could afford to buy Taylor’s book to add it to my collection: I’m sure it contains many interesting statements. Its high cost ($39), though, would blow much of my ancient giants research budget for the year. (I’ve signed up for another month’s subscription to newspapers.com so I can keep working on understanding the North American accounts -- so that’s another $7.95 that I’ve committed and we're barely halfway through January). Maybe I should start asking for donations. Or maybe I could start selling casts of large femurs. How about someone sends me a letter saying they saw a large femur once in some place – doesn’t really matter where – and I’ll start making casts. The bigger the better: the going rate seems to be $9.57/inch.

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$502 Reward for Photographs of Lost Giants: The Skeletons from Delavan, Wisconsin

12/23/2014

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Delavan, Wisconsin: not home to giant Nephilim skeletons.

Talk show host and giant Nephilim enthusiast L. A. Marzulli has offered a $500 reward for a photograph from the 1911 excavations at Delevan, Wisconsin. The article on Marzulli’s blog states:

The Delavan skeletons’ purported sizes, ranging from seven to nine feet tall, with abnormally large skulls, are consistent with other skeletal remains which Marzulli said fit the Nephilim profile.

Locating photographs, notes, maps, and other documentation related to an old excavation is a worthy endeavor that I fully support. I’ve spent time myself trying to piece together whatever information I could to aid in interpreting and understanding past work at sites like Clark’s Point in the Falls region of the Ohio Valley and some 1960s Late Woodland mortuary sites in southern Indiana. A single map or photograph can sometimes have a great impact on one’s ability to construct some framework for understanding the material remains from unpublished or under-published archaeological investigations.

So I think some new evidence about the Delevan skeletons would be a wonderful thing, and I would like to put some cash on the line as well. While Marzulli’s $500 reward for a photograph is not something I can match (I don’t have talk show host money, just Visiting Assistant Professor money), I decided I could chip in something to help the cause. At first I committed to a dollar, but as I did some research on the Delavan accounts and became more and more interested in helping to solve this “mystery,” I decided to double my contribution. Together with Marzulli’s $500, my two bucks will bring the total reward for a Delavan photograph to $502. If that doesn’t push the gas pedal down to the floor, I don’t know what will.

But I have very different expectations than Marzulli about what those photographs, if they exist, will show. SPOILER ALERT: there was nothing giant, mysterious, or particularly unusual about the skeletons either from 1911 or 1912. The 1911 stories that I have seen contain no information that suggests anything but Native American remains disinterred from a mound. The 1912 stories about Delavan, which emphasized a suite of strange cranial features, were composed and spread in the context of the ongoing search for the “missing link” between apes and humans that was the focus of the accelerating study of human evolution. This historical context explains the particular language and claims about the characteristics of the 1912 skeletons that we see in the stories, as well as the headlines.

Let’s look at the accounts.

The Delavan Accounts

Those familiar with the modern mythology of giants have heard of Delevan before: the accounts from Delavan are a staple among those making a claim that a “race” of giants existed in prehistoric North America. A Google search for “Delevan skeletons” returns several pages of websites that have posted, transcribed, or paraphrased an article in the New York Times from May 4, 1912, with the headline “Strange Skeletons Found:”

STRANGE SKELETONS FOUND.
__
Indications That Tribe Hitherto Unknown Once Lived in Wisconsin.
Special to the New York Times.

    MADISON, Wis., May 3.—The discovery of several skeletons of human beings while excavating a mound at Lake Delavan indicates that a heretofore unknown race of men once inhabited Southern Wisconsin. Information of the discovery was brought to Madison to-day by Maurice Morrissey, of Delavan, who came here to attend a meeting of the Republican State Central committee. Curator Charles E. Brown of the State Historical Museum will investigate the discoveries within a few days.
    Upon opening one large mound at Lake Lawn farm, eighteen skeletons were discovered by the Phillips Brothers. The heads, presumably those of men, are much larger than the head of any race which inhabit America to-day. From directly over the eye sockets, the head slopes straight back and the nasal bones protrude far above the cheek bones. The jaw bones are long and pointed, bearing a minute resemblance to the head of the monkey. The teeth in the front of the jaw are regular molars.
    There were also found in the mounds the skeletons, presumably of women, which had smaller heads, but were similar in facial characteristics. The skeletons were embedded in charcoal and covered over with layers of baked clay to shed water from the sepulcher.

Similar stories ran in a number of other newspapers during the spring of 1912. I have transcribed the ones that I’ve located (available here as a pdf). They all say pretty much the same thing in terms of the description of the skeletons: large skulls, sloping foreheads, protruding nasal bones, and jaws like a monkey or an ape. The descriptions that mention the teeth say the front teeth are “regular molars.”   Many of the headlines emphasize the “strangeness” of the remains and use phrases like “unknown race.” Two of the accounts actually specify that the skulls were unusually small rather than unusually large.

The 1912 excavations appear to have been conducted in a different mound from the 1911 excavations. I only found one account of the 1911 excavations (Belvidere Daily Republican, April 12, 1911):

FIND INDIAN RELICS NEAR LAKE DELAVAN
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Fourteen Are Unearthed Beneath Knoll Where Chicagoans Camp.
__

   Lake Delavan, Wisconsin – Out of a knoll that for years has formed the playground of thousands of Chicago people during the summer months, Phillips Bros., owners of Lake Lawn farm, have just dug fourteen human skeletons, and the probability is that still other finds will be unearthed.
    For years it has been suspected that the big mound on which several Chicago church choirs have been accustomed to camp, one after another, in different years, contained rich Indian relics, but no one seemed to make a move toward exploration.
     As the result of an argument as to what was hidden in the mound, the owners of the place dug down eight feet and raked out skeletons which are probably the largest specimens of the red race found in southern Wisconsin. Two of the skeletons were found in a sitting posture. All were buried in a stone-floored and walled pit, over which a solid clay slab had been placed.
    The skeletons have been preserved intact and will go to the state museum at Madison.
    Walworth county has a very large number of the mounds, some of them having been explored, with the result that only a few relics, most of them crude weapons, were found.

I’m not sure exactly what Mazulli is expecting to find in photographs from the 1911 excavations at Delavan, but I’m guessing from the story on his blog that he hopes to use photographic evidence to support his claim that the Delevan skeletons were in the “giant” range of human stature (i.e., over 7’ tall). He claims to have demonstrated that a photo from Catalina Island, California, shows a skeleton from an individual that would have been over 8’6’ tall. I didn’t find any accounts that give height estimates for the Delavan skeletons, so I have no idea where his information about 7’-9’ skeletons comes from. Perhaps there is some newspaper account or source out there that gives these specific height estimates. They certainly don’t appear in the accounts that I found.

Were the remains from Delavan the skeletons of giant Nephilim as Marzulli claims?

No. Here's what the accounts were really trying to describe.

The Delavan Accounts in a Historical Context: The Search for Human Ancestors

The early 1900s was an interesting time in the study of human evolution. Darwin had published On the Origin of Species in 1859, and the hunt was on for fossils that could demonstrate a “missing link” between humans and apes. Neandertal fossils had been known from Europe since the 1820s, but those remains were too similar to modern humans to qualify as a “missing link.” Eugene Dubois had discovered fossils of “Java Man” (later named Homo erectus) in Indonesia in the 1890s. Although Darwin had hypothesized that early human ancestors would be found in Africa, no fossils had yet been located (the first australopithecine, Taung Child, was not discovered until 1923).

The original remains of "Java Man." Note the sloping forehead.

Scientists in the first decade of the 1900s were busy looking for fossil material and arguing about whether Dubois’ “Java Man” was an ape or a human. Those remains consisted of a skull cap, a femur, and a molar tooth. The “missing link” conception of evolution led to an expectation that a human-ape ancestor would have a mixture of human-like and ape-like features. The year 1912, in addition to being the year of the Delevan stories, was also the year that the Piltdown skull (a fraudulent skull that was constructed from the cranium of a human and the jaw of an orangutan) made its public debut. While the lack of fossil material left open questions about both the geographic location of human origins and the characteristics of human ancestors, there was an expectation that those “missing link” ancestors would have some characteristics of human and some characteristics of apes.

Stories about human evolution and the remains of Neandertals and “Java Man” were being printed in newspapers in the early 1900s. A 1911 article with the headline “When Man Came on Earth” (Moberly Weekly Monitor, February 3, 1911) describes “the ape-man of Java:”

"He was a little more than five feet tall and stood erect, though still with the strong curve to his back inherited from a quadruped ancestor. He had a heavy face with retreating forehead, bulging teeth, massive jaws and receding chin."

An article titled “Blurred Beginnings of Mankind” (Kansas City Star, March 5, 1911) described the skulls of Neandertals:

"A low, receding forehead topped his skull. The nose was flat, the nostrils large, the jaw heavy, the chin small and receding. Two thick, bony ridges stood over his eyes. The skin may have been copper colored and the hair on it was thick. The large teeth bulged outward. His frame was canted forward a trifle."

Short stature and receding foreheads were common, publicized characteristics of both kinds of fossil “ape-men” that were known in the early 1900s. Newspaper articles also mentioned the size of the fossil skulls with regard to their cranial capacity: smaller than humans in the case of “Java Man,” larger than humans in the case of Neandertals. The figure to the right shows a drawing of a Neandertal skull that appeared in the June 17, 1911, edition of the Cincinnati Enquirer. The drawing clearly shows the sloping forehead and the protruding nasal bones.

It was in the context of this information about the characteristics of known fossils and the global hunt for the “missing link” that the stories of the Delevan skeleton were written.

The Intent of the Delavan Accounts

I think it is pretty clear that the goal of the 1912 newspaper story was to promote the idea that Delavan skeletons were somehow important to human evolution. That is why the stories describe skulls with sloping foreheads, protruding nasal bones, and monkey- or ape-like jaws. Many of the stories emphasize that the skeletons belong to an “unknown race,” and one headline even proclaims that the skeletons “May Prove Darwin Theory.”

In the 1912 story, there is no mention of the Native American affiliation of the remains (as specified in the 1911 story), and no mention of large stature or body size.

The 1912 description of the skulls was apparently provided by "attorney Maurice Morrissey" from Delavan. I do not know what Morrissey’s agenda was or what his qualifications were for describing skulls, but the features he chose to emphasize certainly resonated with the characteristics of the known “ape-man” fossils that were being described in the press. The identification of the front teeth as “regular molars” makes me doubt that he had any serious anatomical training. He was undoubtedly mistaking well-worn incisors for molars (if the account had been written a few decades prior, it probably would have called the front teeth “double teeth” or used the phrase “double teeth all around”).

The differences between the 1911 and the 1912 accounts from Delavan are telling. While the remains encountered in 1911 and 1912 were probably pretty similar, the stories about the remains were written with very different agendas. The 1911 accounts were of large Native Americans. The 1912 accounts were of a possible human ancestor with all the characteristics one would expect to find in the skeletons of "ape-men."

The similarities between the 1912 descriptions from Delavan and Ellensburg (also from 1912) are striking (more on that later).

What the Giantologists Got Wrong

In this case, it might be easier to address what the giantologists got right:

Wisconsin.

They appear to have gotten the site in the correct state. Other than that, I don't see a whole lot of merit in how the giantologists have treated the Delavan accounts.

Are these the skeletons of giants? I’m honestly not sure where that idea comes from. It is certainly nowhere in the newspaper stories from 1911 or 1912 that I have located. The claim for a 7'-9' height made on Marzulli's webpage is repeated in many other locations on the web that only reference the New York Times article. I honestly have no idea where that piece of the story originates--I do not know if there is some basis for it or if it’s a total fabrication. If someone can point me to a source for the specific height claim I would love to have a look at it.

In some cases, the remains from Delavan have grown even larger. One webpage about Delavan specifies that:

"These alleged findings were first reported on May 4, 1912. It stated that these skeletons had heights which ranged from 7.6 feet up to 10 feet and the skulls were much bigger than the heads of any type of person who lived inside America today. The story also said the skulls had double rows of teeth, six toes on each foot and six fingers on each hand. It was also reported that these bones were believed to belong to beings that could have even been aliens."

Not only have the skeletons gotten taller, but they've grown extra digits, extra teeth, and possibly been extraterrestrials. I shouldn't have to say it, but that description appears to contain considerable embellishments that are not present in the May 4, 1912, story in the New York Times.

The Delavan skeletons have become part of the lore of the new mythology of giants. In the hundred years since their discovery, they have grown in size and become amplified in significance. In reality, however, the stories from Delavan that I have seen appear to describe Woodland-period Native American remains disinterred from artificial burial mounds. The story from Delavan changed from 1911 to 1912 as someone saw an opportunity to attract attention by casting the remains in a light that would make them appear relevant to the unfolding story of human evolution. The reported features that were "strange" about the skeletons were characteristics that made them appear more like a possible human ancestor.

I hope the $502 on the table flushes out some new information about Delavan. I’m supposing that Marzulli is interested in the 1911 excavations because the story from that year actually specified that the skeletons were “probably the largest specimens of the red race found in southern Wisconsin.” The 1912 accounts mention nothing about the size of the skeletons, which makes sense because great height was not associated with fossils of earlier humans (Neandertals and “Java Man”) known in 1912. At any rate, if photographs from the excavation do surface, they will show skeletal remains that fall within the normal range of human variation. They will be of regular height, with regular-sized heads, with regular features of modern humans.

That will be $2 well spent.

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The Modern Mythology of Giants Facebook Page: Why the Heck Not.

12/8/2014

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I've gotten a nice response to my recent posts on giants and pseudo-science, mostly from professional and avocational archaeologists. It has been fun so far, and I hope to keep some momentum. I just started a Facebook page called The Modern Mythology of Giants as a way to try to reach broader, non-archaeologist audience. I will post links there to everything relevant that I write here. Please "like" the page if you're interested in following along through Facebook, and please don't hesitate to jump in if you've got something to contribute.

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What's a "Species"?

Human Evolution and the Stone Tool "Problem"

The Dependency Ratio in Human Evolution

Australopithecine Sexual Dimorphism: What's Love Got to Do With It?

Was Birth Assistance Among Early Hominids a Gendered Activity?

Fetal Head Molding and Obstetrics in Late Pleistocene Humans

Evolution, "Devolution," and the Incredible Shrinking of Humanity: Why Creationists Love Giants

Joe Taylor's Sculpture of a 47" Femur: What's the Story?

$502 Reward for Photographs of Lost Giants: The Skeletons from Delavan, Wisconsin

The Modern Mythology of Giants Facebook Page: Why the Heck Not.

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