This week's announcement that a 10,000-year-old resident of Britain had dark skin and blue eyes has added another data point to our understanding of the complex and fascinating evolution of variability in human pigmentation. DNA analysis was used to give "Cheddar Man" a makeover:

The portrait of a dark-complected Cheddar Man has upset many racist modern Britons, who were comfortable with a lighter-skinned ancestor.  White supremacists are attributing the change in Cheddar Man's skin tone to political correctness, cultural Marxism, and a hoax perpetrated by the UN and Jewish scientists.

These blanket rejections of the science responsible for Cheddar Man's new look come from the same crowd that, just two weeks ago, hailed the announcement of a 200,000-year-old "modern human" fossil from Israel as a significant blow to the Out of Africa theory. Oh you fickle racists.

In reality, the claim that a European from the Early Holocene probably had dark skin and blue eyes is unsurprising in light of other recent work suggesting that lightened skin pigmentation emerged relatively recently in European populations. These conclusions are not the result of agenda-driven guesswork, but of direct analysis of DNA. Have a look at the paper from the La Brana specimen for an example.

Data on the recent emergence of "whiteness" among European populations undercuts the white supremacist notion that light skin tone is ancient, "special," and somehow linked to inherent biological/cultural superiority. It's a very short step from the modern mythologies of white supremacy into numerous threads of pseudo-archaeology, many of which depend on the existence of ancient "white gods," "white giants," "white Atlanteans," etc.

​The real stories of human variability are much more interesting than the fantasy ones. I recommend embracing evidence. 

It's the end-of-semester crunch for many of us in the academic world. My Facebook feed is filled with posts by people who been grading for too long and finding too many cases of student plagiarism. The end of my road was easy this semester, as I taught a very pleasant field school populated by a good group of students. Having taught a 4/4 one year, I feel for all of you still slogging away.

I wanted to take a minute to write about two stories related to claims for sites of Middle Pleistocene age in two different corners of the world. Unless you're grading papers in a lead-lined underground bunker, you heard about the claim for a 130,000-year-old archaeological site in California that was published in Nature yesterday. That's the first one. The second one involves an age estimate of 250,000 for the Homo naledi remains first described in September of 2015. The first claim is buzz-worthy because of its extreme earliness (a good 115,000 years prior to what most archaeologists accept as good evidence for human entry into the Americas). The second claim is surprising for its lateness.  Let's do the second one first.

Homo naledi is Only 250,000 Years Old?

The announcement of Homo naledi and the results of the Rising Star Expedition made a huge splash in the fall of 2015 (I gave my take on it here). One of the main unresolved issues at the time of the initial announcement was that the remains were not dated.  The lack of an age estimate made it difficult to frame the analysis in terms of evolutionary relationships with other hominins and the implications of the claims that Homo naledi was burying its dead. If the remains are very early (say, close to 2 million years old . . . ), the claims for organized mortuary behavior are spectacular. If they're very late, the mosaic of primitive and derived features becomes very curious. 

Two days ago, the New Scientist ran a story titled "Homo naledi is Only 250,000 Years Old -- Here's Why that Matters."  Here is a quote from that piece:

"Today, news broke that Berger’s team has finally found a way to date the fossils. In an interview published by National Geographic magazine, Berger revealed that the H. naledi fossils are between 300,000 and 200,000 years old.
​
“This is astonishingly young for a species that still displays primitive characteristics found in fossils about 2 million years old, such as the small brain size, curved fingers, and form of the shoulder, trunk and hip joint,” says Chris Stringer at the Natural History Museum in London."

If you click on the link to the interview in National Geographic, you'll find that it leads to a photograph of a magazine page posted on Twitter by Colin Wren. I'm unable to access the original piece in National Geographic. I'm not quite sure what is going on, but presumably a formal publication explaining the age estimate is in the works and will be out soon. 

A 250,000 year age would, indeed, be surprising. Previous age estimates have ranged widely, from 900,000 years old  (based on dental and cranial metrics) to 2.5 to 2.8 million years old (based on overall anatomy). Age estimates based on the anatomical characteristics of the remains are problematic, obviously, as they rely on assumptions about the pattern, direction, and pace of evolutionary change that may not be correct. Hopefully the latest age estimates are independent of the anatomy (i.e., have a geological basis). This blog has some additional background.

And now on to the second one, which concerns . . .

A Middle Pleistocene Occupation of North America?

It's hard to know where to even start with this one. The claim is bold, the journal is prestigious, the popular press has been all over it, and the reaction from professionals has been swift and (as far as I can tell) overwhelmingly negative. The reactions I have seen among my colleagues and friends have been almost universally skeptical, ranging from amusement to mild outrage. I'll just summarize all that with gif I saw in an online discussion about the paper:

The claim centers around an assemblage of stones and mastodon bones that the authors interpret as unequivocal evidence of human activity in California at the Middle/Late Pleistocene transition (ca. 130,000 years ago). Here is the first part of the abstract of the Nature paper by Steven Holen and colleagues:

"The earliest dispersal of humans into North America is a contentious subject, and proposed early sites are required to meet the following criteria for acceptance: (1) archaeological evidence is found in a clearly defined and undisturbed geologic context; (2) age is determined by reliable radiometric dating; (3) multiple lines of evidence from interdisciplinary studies provide consistent results; and (4) unquestionable artefacts are found in primary context. Here we describe the Cerutti Mastodon (CM) site, an archaeological site from the early late Pleistocene epoch, where in situ hammerstones and stone anvils occur in spatio-temporal association with fragmentary remains of a single mastodon (Mammut americanum). The CM site contains spiral-fractured bone and molar fragments, indicating that breakage occured while fresh. Several of these fragments also preserve evidence of percussion. The occurrence and distribution of bone, molar and stone refits suggest that breakage occurred at the site of burial. Five large cobbles (hammerstones and anvils) in the CM bone bed display use-wear and impact marks, and are hydraulically anomalous relative to the low-energy context of the enclosing sandy silt stratum. 230Th/U radiometric analysis of multiple bone specimens using diffusion–adsorption–decay dating models indicates a burial date of 130.7 ± 9.4 thousand years ago. These findings confirm the presence of an unidentified species of Homo at the CM site during the last interglacial period (MIS 5e; early late Pleistocene), indicating that humans with manual dexterity and the experiential knowledge to use hammerstones and anvils processed mastodon limb bones for marrow extraction and/or raw material for tool production." 

The 130,000 year-old date is way, way, way out there in terms of the accepted timeline for humans in the Americas. Does that mean the conclusions of the study are wrong? Of course not. And, honestly, I don't even necessarily subscribe to the often-invoked axiom that "extraordinary claims require extraordinary evidence." I think ordinary, sound evidence works just fine most of the time when you're operating within a scientific framework. Small facts can kill mighty theories if you phrase your questions in the right way.

So how should we view claims like this one? For this claim to stand up, two main questions have to withstand scrutiny. First, is the material really that old? Second, is the material really evidence of human behavior?

If we accept the age of the remains, we're left with the second question about whether those remains show convincing evidence of human behavior. As you can see from the abstract, the claim for human activity has several components (modification of the bones, the presence and locations of stone cobbles interpreted as tools, etc.). The authors contention (p. 480) is that

​"Multiple bone and molar fragments, which show evidence of percussion, together with the presence of an impact notch, and attached and detached cone flakes support the hypothesis that human-induced hammerstone percussion was responsible for the observed breakage. Alternative hypotheses (carnivoran modification, trampling, weathering and fluvial processes) do not adequately explain the observed evidence (Supplementary Information 4). No Pleistocene carnivoran was capable of breaking fresh proboscidean femora at mid-shaft or producing the wide impact notch. The presence of attached and detached cone flakes is indicative of hammerstone percussion, not carnivoran gnawing (Supplementary Information 4). There is no other type of carnivoran bone modification at the CM site, and nor is there bone modification from trampling."

My impression is that most archaeologists are, like me, are skeptical that all other possible explanations for the stone and bone assemblage can be confidently rejected. I'm no expert on paleontology and taphonomy, but as I thought through the suggested scenario, I wondered how all the meat came off the bones before before the purported humans smashed them open with rocks. The authors state that there's no carnivore damage, and unless I missed it I didn't see any discussion of cutmarks left by butchering the carcass with stone tools. So where did the meat go? If it wasn't removed by animals (no carnivore marks) and wasn't removed by humans (no cutmarks) did it just rot away? If so, would the bones have still been "green" for humans to break them open?  

The absence of cut marks would be perplexing, as we have direct evidence that hominins have been using using sharp stone tools to butcher animals since at least 3.4 million years ago. The 23,000-year-old human occupation of Bluefish Cave in the Yukon is supported by . . . cutmarks. We know that Neandertals and other Middle Pleistocene humans had sophisticated tool kits that were used to cut both animal and plant materials.

Is it possible that pre-Clovis occupations in this continent extend far back into time?  Yes, I think it is. Does this paper convince me that humans messed around with a mastodon carcass in California at the end of the Middle Pleistocene?  No, it does not. 

Some of my friends seem angry that the paper was published. I have mixed feelings. I'm not at all convinced by what I've read so far, but I think claims like this serve a useful purpose whether or not they turn out to be correct. I can understand the concerns I've heard voiced about unfairness in the standards of evidence and argument that are acceptable at various levels of publication, but I also think there should always be room for making bold claims about the past as long as those claims have some basis in material evidence that can be independently evaluated. It will be interesting to see how the buzz over this paper plays out. Will other professionals carefully examine the remains and offer up their opinions? Will the claim be quickly dismissed and forgotten about?

One thing I can guarantee is that the "fringe" will be on the Cerutti Mastodon like a wet diaper:  they've already got a laundry list of "Neanderthal" remains from the New World (some buried in Woodland-age earthen mounds!) and "pre-Flood" sites into which they'll weave this report into. Maybe Bigfoot will even be implicated. Maybe the mastodon was killed by Atlanteans.
​
Onward.

We're now into the fourth week of the semester here at the University of South Carolina. As usual I've been writing for this blog less than I'd like (I have several unfinished draft posts and ideas for several more, and there's currently a backlog of Fake Hercules Swords). A good chunk of my time/energy is going into the Forbidden Archaeology class (you can follow along on the course website if you like -- I've been writing short synopses, and student-produced content will begin to appear a few weeks from now). Much of the remainder has gone into pushing forward the inter-locking components of my research agenda. This is a brief update about those pieces.

Small-Scale Archaeological Data

At the beginning of the summer I spent a little time in the field doing some preliminary excavation work at a site that contains (minimally) an intact Archaic component buried about 1.9 meters below the surface (see this quick summary).  Based on the general pattern here in the Carolina Piedmont and a couple of projectile points recovered from the slump at the base of the profile, my guess is that buried cultural zone dates to the Middle Archaic period (i.e., about 8000-5000 years ago).​

My daughter washed some of the artifacts from the site over the summer, and I've now got an undergraduate student working on finishing up the washing before moving on to cataloging and labeling. Once the lithics are labeled we'll be able to spread everything out and start fitting the quartz chipping debris back together. Because I piece-plotted the large majority of the lithic debris, fitting it back together will help us understand how the deposit was created. I'm hoping we can get some good insights into the very small-scale behaviors that created the lithic deposit (i.e.,perhaps the excavated portion of the deposit was created by just one or two people over the course of less than an hour).

When the archaeology faculty met to discuss the classes we'd be offering in the spring semester, I pitched the idea of running a one-day-per-week field school at the site. Assuming I can get sufficient enrollment numbers, that looks like it's going to happen. The site is within driving distance of Columbia, so we'll be commuting every Friday (leaving campus at 8:00 and returning by 4:00). The course will be listed as ANTH 322/722. It's sand, it's three dimensional, and it's pretty complicated -- it's going to be a fun excavation. I'll be looking to hire a graduate student to assist me on Fridays, and I'll be applying for grant monies to cover the costs of the field assistant's wages, transportation, and other costs associated with putting a crew in the field. 

Large-Scale Archaeological Data

Some parts of my quest to assemble several different large-scale datasets are creeping along, some are moving forward nicely, and some are still on pause.

Complex Systems Theory and Computer Modeling

Complex systems theory is what will make it possible to bridge the small and large scales of data that I'm collecting. Last year, I invested some effort into transferring my latest computer model (FN3_D_V3) into Repast Simphony and getting it working. I also started building a brand new, simpler model to look at equifinality issues associated with interpreting patterns of lithic transport (specifically to address the question of whether or not we can differentiate patterns of transport produced via group mobility, personal mobility between groups, and exchange).  

As it currently sits, the FN3_D_V3 model is mainly demographic, lacking a spatial component. Over the summer I used it to produce data relevant to understanding the minimum viable population (MVP) size of human groups. Those data, which I'm currently in the process of analyzing, suggest to me that the "magic number of 500" is probably much too large: I have yet to find evidence in my data that human populations limited to about 150 people are not demographically viable over spans of several hundred years even under constrained marriage rules. But I've just started the analysis, so we'll see. I submitted a paper on this topic years ago with a much cruder model and didn't have the stomach to attempt to use that model to address the reviewers' comments. I'm hoping to utilize much of the background and structure of that earlier paper and produce a new draft for submission quickly. I also plan to put the FN3_D_V3 code online here and at OpenABM.org once I get it cleaned up a bit. I also discuss this model in a paper in a new edited volume titled Uncertainty and Sensitivity Analysis in Archaeological Computational Modeling (edited by Marieka Brouwer Burg, Hans Peeters, and William Lovis). 

It will be a relatively simple thing to use the FN3_D_V3 model in its non-spatial configuration to produce new data relevant to the Middle Paleolithic mortality issue I discussed at the SAA meetings a couple of years ago. I'm also going to be working toward putting the guts of the demographic model into a spatial context. That's going to take some time.

Back in September, I wrote this short post about the announcement of an upcoming film called The Solutrean. I have a Google Alert set up for "Solutrean," so when there's a press release about the movie it shows up in my inbox. I also have a Google Alert set up for my own name, just in case. I hope no-one is getting me confused with the Vicar of Baghdad or Nebraska Cornhusker's guard Andrew White III. Those are the Andrew Whites that make the news routinely.

A story two days ago seems to answer the question of whether The Solutrean will have anything to do with the Solutrean Hypothesis with a big "yes:"

"Inspired by the idea tossed around by some folks that Europeans settled in North America over 20,000 years ago, the movie . . .  tells the Ice Age set story about a hunting trip the goes bad, and the tough journey home that follows." 

And in this story:

"Specifically, the title “Solutrean” is a nod to a hypothesis written by scholars who believe that Europeans settled America somewhere around 20,000 years ago."

It sounds to me like they're writing from the same press release.  So the film is, in at least some way, about the Solutrean Hypothesis.

I'm interested in the Solutrean Hypothesis (the idea that Upper Paleolithic peoples from western Europe colonized eastern North America sometime during the period 21,000 to 17,000 years ago) for a couple of different reasons.  First, as a scientific idea, it relates directly to questions about the peopling of the New World and the earliest hunter-gatherers in the Eastern Woodlands. Like many other archaeologists, I'm open to possibility but remain unconvinced and unimpressed by the positive evidence that's been put forth so far (e.g., the Cinmar biface, the other bi-points reportedly recovered from Chesapeake Bay area, the genetic data, etc.).  There have been reports of the discovery of Solutrean assemblages in sites with good context in eastern North America, but (as far as I know) those reports have been thus far limited to stories in the popular media (this story in Popular Archaeology, for example -- edited since I wrote about it here). I can't speak for others, but real publication of those sites is something I'm eagerly awaiting.

Not everyone is as skeptical as me. Some professional archaeologists apparently are convinced by what they've see so far, and it's pretty clear that the Solutrean Hypothesis has a strong following among non-professionals. My sense from comments I get on this blog is that many of you out there feel that the burden of proof has already been satisfied.

I disagree, obviously, and I think the contrast between how professionals and non-professionals generally view the Soloutrean Hypothesis and the strength of the evidence for it illustrates a good degree of daylight between how professional archaeologists and the public at large evaluate ideas about the past. I've been accused of "attacking" the Solutrean Hypothesis because I have expressed skepticism about the evidence, when, in reality, such skepticism is a basic, fundamental part of the process of doing science. Critical evaluation of positive material evidence is absolutely essential to the whole endeavor of understanding the past. I'm not sure when the Solutrean Hypothesis became so sacred and beloved that it was no longer permissible to ask questions like "what is that artifact really telling us?" or "what is the basis of that assertion?" News flash: those kinds of questions are never out of line. The Solutrean Hypothesis is far from being settled science. And, even if does turn out to be correct (i.e., the null hypothesis of "no North American visit by Solutrean-age peoples from Europe" is falsified by a good site), the door will never close on asking pertinent questions about the evidence and the interpretation of that evidence.

So now that we know that The Solutrean will indeed consciously embrace the Solutrean Hypothesis. It's a movie, of course, not science.  But it will be interesting to see how the characters and story of The Solutrean engage and reflect both the scientific and non-scientific parts of the story of the Solutrean Hypothesis. What will the Solutreans look like? Will they encounter any other peoples in their journeys? Will they drop the Cinmar biface while traversing the Atlantic Shelf? 

​We shall see.

Another mention of The Solutrean popped up in my news feed this morning, announcing that Australian actor Kodi Smit-McPhee is nearing a deal to star in the "Ice Age-set survival thriller:"

"Smit-McPhee will play a young man who must cross miles of dangerous, weather-whipped territory to reunite with his tribe."

In a previous post, I wondered if that "dangerous territory" included the New World. Today's stories aren't any more specific than the original ones, but do mention that the story is "set 20,000 years ago in Europe."

In another previous post, I discussed the results of recent genetic analyses that suggested Paleolithic hunter-gatherers in Europe (including Solutrean peoples) were relatively dark-skinned compared to western Europeans today.  

At this point there's no way of knowing what The Solutrean will bring to the table. I would love to see a film about Paleolithic Europe that made a real effort to get the details right and present a vision of the past that is as accurate as it is compelling (i.e., more like The Black Robe and less like 10,000 BC).   I'm hoping The Solutrean is not a film just about a bunch of people who look like modern, white Europeans doing brave things.  Filming is scheduled to start soon.

A story about an upcoming film titled The Solutrean popped up in my news feed this morning. According to the piece, the film will be

"a visually striking epic-adventure . . .  It has to do with a hunting expedition gone awry and a young survivor’s quest to brave the inhospitable and dangerous conditions to find his way back."

My first reaction was to wonder if the young hero's adventures will have him visiting the Americas. Will we see North Atlantic currents carry him away along the pack ice? Will the "inhospitable and dangerous conditions" be provided courtesy of Native Americans? In other words, will the film engage with the central idea of the Solutrean Hypothesis?

My second reaction was to wonder if the Solutreans in film will be depicted as very light skinned, even though recent genetic evidence suggests their skin tone was darker than modern Europeans?

Connected to those was my third reaction: a conflicted mix of excitement and dread.  I think a lot of professional archaeologists will agree with me when I say there really aren't that many good movies that deal with our subject matter.  Movies can have a powerful effect in shaping the public's perception about both what archaeologists do and what the human past was like.  We love to watch movies that put flesh on the bones of things we think about every day, but we're often disappointed in what we see. 

I hope The Solutrean makes some good choices.  No word on when it's slated for release. Casting has begun and the film will be shot in Iceland and Canada.

Last week I wrote a post about the 3.3-million-year-old pre-Oldowan stone tool assemblage reported from the Lomekwi 3 (LOM3) site in Kenya by Harmand et al. (2015).  As I was writing that, I remembered a 2004 paper by Sophie A. de Beaune titled "The Invention of Technology" (Current Anthropology 45(2):139-162) that I had read in grad school.  That paper takes a long-term view of the evolution of technology focusing on the development and proliferation of different kinds of percussion.  Now that we have direct evidence of what kinds of stone tool technologies preceded Oldowan, I wanted to take another look at de Beaune's work.

Her basic premise, if I understand it, is that one can create a "phylotechnical tree"  of actions associated with different kinds of percussion.  Following Leroi-Gourhan (1971), her use of the term "percussion" includes actions such as sawing, chopping, cutting, and puncturing.  All of these different actions would ultimately have had a common origin in what de Beanue calls "thrusting percussion" (using one object to forcefully strike another with the intent of cracking or smashing it). The primacy of thrusting percussion is supported by its ethnographically-observed use among chimpanzees: some chimps crack hard fruits by smashing them between a hammer and an anvil.  Thus, de Beaune argues, thrusting percussion would have been utilized by the earliest hominids and preceded the more formalized stone tool technologies we can recognize in Oldowan.

How, why, and when did thrusting percussion, perhaps first used solely as an action employed to crack animal or vegetable materials, begin to be used to used to crack stone?  Those are the questions that can potentially be addressed directly by the assemblage reported from LOM3 (and hopefully more to be found in the future). 

To the "when" question, LOM3 answers "by at least 3.3 million years ago."  It's hard to imagine that the earliest identified example of something actually marks its earliest occurrence, so it's probably safe to presume that the behaviors that created LOM3 were present sometime prior to 3.3 MYA.

The first publication on 149 pieces of worked stone from LOM3 also gives us some insight into the "how" question.  According to the authors (pp. 311-312), the assemblage contains 83 cores (pieces of stone used for the removal of flakes) and 35 flakes.  The remainder of the stone pieces are interpreted as "potential anvils" (n=7), "percussors" (n=7), "worked cobbles" (n=3), "split cobbles" (n=2), and indeterminate fragments (n=12). You can see 3D digital models of some of the artifacts here.  

The LOM3 cores are not small.  The mean mass is 3.1 kg (6.8 pounds): that's heavier than a standard brick but lighter than your average bowling ball.  The flakes, anvils, and percussors are large, also, compared to those from later Oldowan sites and from those in assemblages produced by wild chimpanzees (p. 313). Although some artifacts have a series of flakes detached, patterns of fracture and flake removal suggest to the authors that the "precision of the percussive motion was also also occasionally poorly controlled" (p. 313):

"The dimensions and the percussive-related features visible on the artefacts suggest the LOM3 hominins were combining core reduction and battering activities and may have used artefacts variously: as anvils, cores to produce flakes, and/or as pounding tools. . . . The arm and hand motions entailed in the two main modes of knapping suggested for the LOM3 assemblage, passive hammer and bipolar, are arguably more similar to those involved in the hammer-on-anvil technique chimpanzees and other primates use when engaged in nut cracking than to the direct freehand percussion evident in Oldowan assemblages." (p. 313)

That sounds to me like a description that's pretty consistent with a manufacturing strategy based largely on chimp-like "thrusting percussion," and perhaps exactly what one would expect to precede Oldowan based on de Beaune's analysis.

What about the "why" question? What caused hominids to start using thrusting percussion to produce tools?  Answering that question is tougher than addressing the "when" and "how" questions. 

I don't think it has much to do with a change in physical anatomy -- specifically that of the hand -- for three inter-related reasons.  First, as I discussed before, I think there's a lot of evidence that suggests that hands with the capacity for human-like precision gripping were widespread among early hominids, including the australopithecines of around 3.3 MYA.  (See also this comment on australopithecine hands that just came out in Science today.)  Second, as discussed by de Beaune (p. 141-142), the physical actions required to smash one rock with another are not all that different than the actions required to smash a piece of fruit on an anvil: no new anatomy was even required to shift the "target" of the percussion to stone.  Third, even with the limitations imposed by their hand anatomy, chimpanzees can be taught to use freehand percussion to make stone tools (see this video of Kanzi, for example).

If the "invention of technology" (meaning, in this case, chipped stone technology) wasn't dependent upon a change in anatomy, what about a change in cognition? Again following Leroi-Gourhan, de Beaune (2004:142) discusses the nature of the distinction between using a hammerstone to smash something to process food and hitting a stone with another stone to produce a cutting edge:

"While these activities involved related movements, that of intentionally splitting a cobble to produce a cutting tools, although "exceedingly simple," was in [Leroi-Gourhan's] view eminently human in that it "implied a real state of technical consciousness.""

Maybe there does have to be a cognitive change to explain the shift to producing and using stone tools.  But, as we know from the Kanzi example, there's nothing lacking in the chimp brain that prevents them from making and use simple chipped stone tools when they're taught.  But, as far as we know, they have to be taught (the last time I checked, though, humans also need to be taught to do it).

Surely an important thing to understand about the shift to using stone-on-stone percussion to make stone tools is what that shift gets you: a tool with a cutting edge unlike anything that exists in nature.  A sharp-edged flake can be used for what de Beaune calls "linear resting percussion"  (cutting and chopping).  You can do a lot of things with an edged tool that you can't do with a blunt one (and that you can't do with your teeth if, like australopithecines, you lack the large canines of chimps and many other non-human primates).  You can sharpen a stick. You can grate and slice plants. And you can cut meat from bones and disarticulate an animal carcass by severing ligaments.  We have some direct evidence of this last activity in the form of the 3.4-million-year-old cutmarked bones reported from Dikkika, Ethiopia, in 2010.  Maybe the battlefield of the hunter-scavenger debate, now several decades old, will be reinvigorated by a transplantation from the Pleistocene to the Pliocene.

Does the emergence of chipped stone technologies during the Pliocene signal an adaptive shift, a cognitive shift, or both?  With the publication of the LOM3 tools and the announcement last week of a new fossil australopithecine from about the same time period and neighborhood, East Africa 3.3 million-years-ago sounds like a pretty interesting place to be.  If, as suggested by ethnographic data from chimps, gorillas, and orangutans, the capacity to use tools is really a homology that extends deep into the Great Ape lineage, it's probably not fair to refer to the production of chipped stone tools as the "invention of technology."  But it is a watershed nonetheless.  The shift to using one set of tools (hammers and anvils) specifically to make other, qualitatively different tools (cutting implements) that potentially open up new subsistence niches and eventually (possibly) become involved in the feedbacks between biology, technology, and culture which are entangled in the emergence of our genus is something worth knowing about:  who did it?  why? what were the tools used for? what changed as a result? 

The assemblage from LOM3 opens up a tantalizing window on those questions.  In those 149 pieces of stone, we have evidence of a stone tool production strategy that used "passive hammer" techniques to produce cutting tools, somewhere in time much closer to the dawn of stone tool production than anything called Oldowan.  Judging by the size of the cores and flakes, the technique appears to have been more dependent on brute force than finesse.  The results, however -- the creation of cutting tools from a natural setting that provided none -- may have been transformational.  I look forward to seeing how the data from the small LOM3 assemblage get incorporated into models of human evolution, and I hope that people working in East Africa are already busy finding more sites.  And I hope that people working outside of East Africa are actively searching for stone tools in Pliocene deposits.  It's a great time to be following paleoanthropology.

Leroi-Gourhan, A. (1971). L'Homme et la Matiere. Paris: Albin Michel.

This week, Darrin Lowery responded to questions raised about the circumstances of the discovery of the Cinmar biface, a bi-pointed stone tool that resembles, at least superficially, artifacts made and used by the Solutrean peoples of Upper Paleolithic Europe.  The point was reportedly dredged up in 1970 by a scallop boat named the Cinmar (hence the name) operating off the Atlantic coast of North America, and associated with mastodon bones that were radiocarbon dated to 22,760 +/- 90 RCYBP (UCIAMS-53545).  The Cinmar biface has assumed a prominent place in the debate about the Solutrean hypothesis (the idea that Upper Paleolithic peoples from western Europe colonized eastern North America sometime between about 21,000 to 17,000 years ago), even gracing the cover of the 2013 book about the idea by Dennis Stanford and Bruce Bradley, its two main advocates.

The circumstances of the Cinmar discovery were called into question in a paper by Metin Eren, Matthew Boulanger, and Michael O'Brien titled "The Cinmar Discovery and the Proposed Pre-Late Glacial Maximum Occupation of North America," published in the Journal of Archaeological Science (JAS) in March of this year.  Eren et al. questioned the history and details of the find, focusing particularly on inconsistencies and omissions in the various accounts of the discovery.  The JAS is a high profile venue, and the paper by Metin et al. generated a significant amount of discussion among archaeologists interested in the peopling of the Americas.

Full disclosure: I consider Metin Eren a friend of mine.  We have some overlapping research interests, and have occasionally exchanged emails and papers.  I think we've even had beers together at one or two professional conferences.

I should also say that I'm very skeptical of the Solutrean hypothesis.  The claim of a trans-Atlantic colonization of North America during the Last Glacial Maximum is an extraordinary one, and I have seen nothing so far that convinces me it is correct. I'm not alone.  The Solutrean hypothesis does not enjoy widespread support among North American archaeologists for a number of reasons (see this 2014 exchange for some summary arguments).  Unfortunately, it has captured the imaginations of some ugly elements outside of the professional community, serving as the basis for white supremacist and neo-Nazi fantasies about the importance of white people to North American prehistory.  That's not the fault of the developers and proponents of the idea, but it's a social dimension to the Solutrean hypothesis that is nonetheless worth being aware of and keeping an eye on.

After reading through both the JAS paper and Lowery's self-published response, I can't say much has changed for me.  The discussion about the circumstances of the Cinmar discovery is an interesting one (especially if you like to see an argument), but it's a debate about the details of a single discovery that, in my opinion, doesn't have the power to "prove" anything either way. Despite its appearance on the cover of a book and a charged exchange about the credibility of the artifact and those who are interested in it, the Cinmar biface doesn't really matter. 

Let me explain what I mean by that.

On the one hand, what if the case for the Cinmar biface is materially flawed and you just have to throw it out?  Eren et al. ask several pointed questions about the discovery, any one of which could potentially sink it as a reliable piece of evidence. Maybe we can't be sure it was in the same dredge load as the mastodon bones, or maybe we can't be sure the artifact was even recovered at sea.  So maybe the Cinmar biface means nothing in archaeological terms because we just can't trust it. 

But, on the other hand, what if everything about the Cinmar discovery is "best case scenario" for the Solutrean hypothesis? Let's the say we can be sure the point was dredged up in 1970 in the same immediate area as some mastodon remains - what does that actually get us? The "association" between the point and the fauna (on which the age estimate is based) is still incredibly weak, leaving us still with just a single stone point largely without context.  Is that the kind of "site" that will change anyone's mind about something as significant as the first colonization of the Americas?  I don't think so, and history agrees with me. Think about the sites that have been pivot points in our acceptance of alternative ideas about prehistory in the western hemisphere: L'Anse aux Meadows, Monte Verde, Folsom . . . those were all sites with clear evidence that falsified an existing model. Proponents and skeptics could stand there together and look at the deposits and have a meeting of the minds about what they meant.  That's never going to be the case with something like the Cinmar biface.  A point that "resembles" a Solutrean artifact with a provenience of "same dredge load as some mastodon bones" is not at the level of a site like Monte Verde - not even close.  Under the most charitable reading it doesn't have the power to move the needle on acceptance of the Solutrean hypothesis.  By itself it's just not a game changer.

What would be a game changer? Proponents of the Solutrean hypothesis are going to have to find, excavate, and document a real site: good artifacts in good contexts with good dates. Period. If the hypothesis is correct, those sites should be identifiable.  The Cinmar biface was made from an inland raw material source, so there should be some sites on dry land with clear evidence of a Solutrean occupation.  All you need is one. One good site trumps dozens of finds of purported Solutrean or Solutrean-like artifacts with poor or no context.  Think about how many sites with "associations" between stone projectile points and extinct fauna were dismissed in North America prior to the acceptance of the antiquity of humans in the New World demonstrated by careful excavations at the Folsom site.  The Solutrean hypothesis will ultimately need something similar.

The burden of proof in this situation pretty clearly has to be on the advocates of the Solutrean hypothesis: it is impossible to use material evidence to prove that Solutrean peoples did not make it to North America (just as we cannot prove they are not currently orbiting the sun in a teapot). The falsifiable hypothesis in this case is that there was no colonization of North America by Upper Paleolithic peoples from Europe.  That's what would need to be proved wrong. Does the Cinmar biface, even under the best of circumstances, do that?  I would say no.  And I would also say that eliminating the Cinmar biface as a piece of evidence doesn't "disprove" the Solutrean hypothesis. Basically, I think that with or without the Cinmar biface the Solutrean hypothesis remains an idea based on an assemblage of circumstantial evidence, none of which at this point appears to be critical to whether the hypothesis is viable or not.  I think the Cinmar biface would not change that equation for me even if I had plucked it from the dredge myself.  It's just not enough.

Other than it's relevance to archaeology, the Cinmar discussion is interesting because of the speed and openness with which it's taking place.  The JAS paper was published open access, so it's available to everyone. Lowery published his response less than two months later on Academia.edu (again, available to everyone).  I'm not sure if there's a precedent for this sort of thing - we may be watching something new.  It will be interesting to see if the discussion continues and, if so, at what pace and in what format. 

Even though I don't think the Cinmar biface is as crtitical to the viability of the Solutrean hypothesis as it has been made out to be, I do welcome the vigorous questioning of evidence.  I think it tells you something important about where the debate about the Solutrean hypothesis is at the moment: it's a lot of energy expended over the minutiae of an artifact that greatly diminishes in perceived importance if a single "good" site can be located.  That's what I'll be watching for.

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? 

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.