It's been two weeks since my last blog post.

I've spent much of that two weeks away from my computer, which has been a nice change. Since the semester ended, I've been working in the field, doing stuff around the house and with my family, and prepping my office for a move. Today I'm relocating from the main SCIAA building to a larger, nicer office suite right in the heart of campus. I'll have plenty of room to ramp up my research, process and analyze artifacts, store collections I'm working on, and (hopefully) start getting some student work going. It's really an amazing thing to have the space -- it's larger and nicer than many fully functional archaeology labs where I've worked in the past.

A 6000-Year-Old Moment Frozen in Time?

Archaeological sites are places that contain material traces of human behavior.  While the human behaviors that create archaeological sites are ultimately those of individuals, we usually can't resolve what we're looking at to that level.  Traces of individual behaviors overprint one another and blend into a collective pattern. The granularity of individual behavior is usually lost.

Usually, but not always.

I spent portions of the last couple of works doing some preliminary excavation work at a site I first wrote about last October. Skipping over the details for now, documentation of an exposed profile measuring about 2.2 meters deep and 10 meters long showed the presence of cultural materials and intact features at several different depths.  The portion of the deposits I am most interested in is what appears to be a buried zone of dark sediment, fire-cracked rock, and quartz knapping debris about 1.9 meters below the present ground surface. 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, I'm guessing that buried cultural zone dates to the Middle Archaic period (i.e., about 8000-5000 years ago).​

The Anthropology of Prehistoric Hunter-Gatherers in the Eastern Woodlands?

Earlier in the month, I had the privilege of visiting the archaeological field schools being conducted at Topper. I wrote a little bit about the claim for a very early human presence at Topper here. The excavations associated with that claim aren't currently active. Field schools focused on Late Pleistocene/Early Holocene (Mississippi State University and the University of West Georgia) and Woodland/Mississippian (University of Tennessee) components at Topper and nearby sites have been running since early May. Seeing three concurrent field schools being run with the cooperation of personnel from four universities (and many volunteers) is remarkable.

On the day of my visit, I gave a talk titled "The Anthropology of Prehistoric Hunter-Gatherers in the Eastern Woodlands?" I argued that not only is it possible to do the anthropology of prehistoric peoples, but it should be a fundamental goal. Skipping over the details for now, I argued (as I have elsewhere) that complex systems science provides a set of tools for systematically trying to understand how history, process, and environment combine to produce the long-term, large-scale trajectories of prehistoric change that we can observe and analyze using archaeological data. I talked about each of the components of my three-headed monster research agenda.  And I got to eat various venison products prepared under the direction of my SCIAA colleague Al Goodyear. And I got to see alligators swimming in the Savannah River.  As a native Midwesterner . . . I anticipate that working near alligators will remain outside my comfort zone for some time to come.

When Did Humans First Move Out of Africa?

Archaeologists love finding the earliest of anything and people love reading about it. While we often want to know how/when new things appear, identifying the "earliest of X" often gets play in the popular press that is disproportionate to its relevance to a substantive archaeological/anthropological question. And you can never really be sure, of course, that you've nailed down the earliest of anything: someone else could always find something earlier, falsifying whatever model was constructed to account for the existing information and moving the goal posts.

Exactly a year ago, I wrote about the reported discovery of 3.3 million-year-old stone tools from a site in Kenya. Those tools are significantly earlier than the previous "earliest" Oldowan tools.  I think they're really interesting but not particularly surprising:  several other lines of evidence (cut marks on bone, tool-use among chimpanzees, and hominin hand anatomy) already suggested that our ancestors were using tools well before the earliest Oldowan technologies appeared.

I anticipate that we still haven't seen the "earliest" stone tool use. 

A recent report from India argues that our ideas about the "earliest" humans outside of Africa also miss the mark. (Note: when I say "human" I'm referring not to "modern human" but to a member of the genus Homo.) This story from March discusses a report of stone tools and cutmarked bone from India purportedly dating to 2.6 million-years-ago (MYA), blowing away the current earliest accepted evidence of humans outside of Africa (Dmanisi at 1.8 MYA) by about 800,000 years. With an increasing number of Oldowan assemblages dating to about 1.8-1.6 MYA are being reported outside of Africa (e.g., in China and Pakistan), would it be that surprising to find evidence a migration pre-dating 1.8 MYA?  Probably not.  Do the finds reported from India cement the case for human populations in South Asia at 2.6 MYA?  Not yet: the fossils and tools reported from India so far (as far as I know anyway) don't have a context that allows them to be convincingly dated.

I had a pleasant conversation with Scott Wolter yesterday. I emailed him to touch base about his participation in my class in the fall, and we ended up talking for about 45 minutes. It was the first time we've spoken and we had more to talk about than we had time to talk. We talked about the Wolter-Pulitzer partnership, of course, but I'm not going ​to go into the details of our discussion (I just invite you to read for yourself Pulitzer's bizarre word salad blog post from Wednesday containing his reference to me as "some back woods rural South Carolina Pseudo-Archaeologist who never worked in the field, but only learned from books").  My sense is that Wolter is someone with whom I can have a frank and vigorous discussion about the merits and interpretation of archaeological evidence and how it is used to evaluate ideas about the past. I'm looking forward to his participation in my class. My plan is to start a Go Fund Me campaign to raise money to fly him down here so he can interact with the students on a face-to-face basis.  

And now the movers are coming for my filing cabinets.  And now my chair is gone.  And now you are up-to-date.

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.

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.