Homo naledi: Handling a Scientific Rorschach Test

by Aaron Jonas Stutz
Lateral view of Dinaledi Hominin 1, the holotype individual for which the new species Homo naledi has been named (Berger et al., 2015).
Lateral view of Dinaledi Hominin 1, the holotype individual for which the new species Homo naledi has been named (Berger et al., 2015).

The recently announced human fossil find site of Dinaledi really–and I mean really–defines the phrase of great scientific importance.

Already, the research team led by Lee Berger has uncovered more than 1500 human bone fragments. There appear to be thousands more–perhaps from dozens of individuals–yet to be excavated. The skeletal remains from the Dinaledi site in South Africa will provide us with so much information about an ancient human population that we are sure to confirm certain hypotheses about human evolution … and–of course–overturn others … and this will be done with a shatteringly unprecedented level of confidence about that population’s biological variability.

It’ll just take some time.

Continue reading Homo naledi: Handling a Scientific Rorschach Test

Read All About It: Oase I Neandertal Admixture Article Published

by Aaron Jonas Stutz
Oase 1 family tree
Can you find the Neandertal great-great-great grandparent? This plausible family tree is based on the paleogenomic analysis of the Oase I (mostly) anatomically modern mandible (Fu et al., 2015).

The Nature publishing group has taken a welcome step toward making the details of scientific research more widely accessible. The flagship cross-disciplinary journal Nature now provides full PDF text views for published articles linked from major media sites. Thus, the article on ancient genetically admixed Neandertal and modern human DNA recovered from the Oase I mandible–work authored by Qiaomei Fu and colleagues–has now been published, and everyone can read the full-text on nature.com. It’s available to everyone via media outlets such as the BBC here. You can click through the hyperlinked text in the BBC story. Now, you can’t download the PDF, but you can view it (apparently only once, as I discovered in trying to verify the BBC link just now) in its entirety in your web browser. It’s not open access, but it’s “opener.”

So what about the full, published version?

Continue reading Read All About It: Oase I Neandertal Admixture Article Published

Measuring the Beginning of the Upper Paleolithic

by Aaron Jonas Stutz

Research on big issues in human evolution–like how Neandertals contributed to our own genetic diversity and to ancient cultural diversity … before they went extinct–certainly involves a level technical nitty gritty that even specialists in the field get worn down by. But sooner or later, we get back up, ready to geek out on the details again. For those of you interested and with institutional access, please check out our newly published article on radiocarbon dating the earliest Upper Paleolithic in the Levant. This is the first major publication on our work on the Mughr el-Hamamah site–work that has been led my Liv Nilsson Stutz and myself … but which has depended on and succeeded thanks to extensive collaboration (Stutz et al., in press). The article may be viewed here, although–as noted above–full access to this Journal of Human Evolution content requires a subscription, so you may be limited to the abstract:


Liv Nilsson Stutz provides a narrated overview of the article here:


In addition, Emory University’s inimitable Carol Clark has published an great overview of the work here: http://esciencecommons.blogspot.com/2015/06/stone-tools-from-jordan-point-to-dawn.html

In this post, I emphasize the key findings from our collaborative research on the Mughr el-Hamamah site, Jordan, and its importance for understanding the beginning of the Upper Paleolithic. I also offer a brief peek at work to come. Continue reading Measuring the Beginning of the Upper Paleolithic

The Protoaurignacian Didn’t Trigger Anything

Or: It’s All About Evolution, Not Revolution …

by Aaron Jonas Stutz
el-Wad point from the Early Upper Paleolithic site of Mughr el-Hamamah, Jordan (Stutz et al., in press). Photograph by Aaron Jonas Stutz CC-BY 2015.
el-Wad point from the Early Upper Paleolithic site of Mughr el-Hamamah, Jordan (Stutz et al., in press). The stone tools from Mughr el-Hamamah date to between 45 and 39 thousand years ago, including some Protoaurignacian-like technologies employed side by side with Levallois point production and expedient flake and bladelet production technologies. Photograph by Aaron Jonas Stutz CC-BY 2015.

We’re now paying particular attention to research on the Protoaurignacian, including the notable recent report by Benazzi et al. (2015). We’ll get to their report below. Let’s start with the Protoaurignacian fuss in the first place. There’s pretty good scientific reason for it. Around 2006, Paul Mellars and João Zilhão–two prehistoric archaeologists who otherwise don’t agree about much–separately presented very similar suggestions, which have turned out to be very influential. In a series papers they separately argued that the Protoaurignacian archaeological artifact pattern–or technocomplex, which I will describe in a bit more detail below–has a clear relationship to anatomically modern human expansion into western Eurasia around 40,000 years ago.

Mellars (2006) suggested that the Protoaurignacian artifact pattern is actually a key component of a complex archaeological marker that traces anatomically modern human colonization of western Eurasia … and thus, also of Neandertal extinction.

Zilhão (2006) argued the same thing about anatomically modern humans, but he suggested that anatomically distinctive Neandertals–as opposed to some Neandertal features inherited by some Early Upper Paleolithic people with mainly anatomically modern ancestry–persisted in parts of Europe until ca. 30,000 years ago. On the one hand, there’s no clear threshold of how many unique derived Neandertal traits you need to be “distinctively Neandertal.” On the other, Zilhão and others pointed out that in Iberia, there are some quite distinctively Neandertal fossils, for which a series of radiocarbon dates had placed at roughly 30 kya. The problem now is that those C14 dates were made on incompletely chemically cleaned and filtered collagen-like material surviving in those bones (Wood et al., 2013, 2014). It turns out that all of the Iberian Neandertals so far re-analyzed with the collagen ultrafiltration pretreatment are actually closer to 50-45 kya in age, associated with Middle Paleolithic stone tools.

But what’s important for investigating the Protoaurignacian archaeological phenomenon is that Zilhão’s hypothesis overlaps significantly with Mellars’s. And if the joint Mellars-Zilhão version is right, then there are two very important observations we would expect to be able make … leading to more complete understanding of anatomically modern human / Neandertal biological turnover (a.k.a. Neandertal extinction). First, the oldest Protoaurignacian-like artifact assemblages should be found closer to the African geographic origin of anatomically modern human populations–that is to say, in the Near East. Second, hominin fossils associated with Protoaurignacian archaeological deposits should have anatomically modern–rather than Neandertal–features. Continue reading The Protoaurignacian Didn’t Trigger Anything

Learning about the Protoaurignacian

… and about the Biocultural Evolution of Paleolithic Technological Systems in General

by Aaron Jonas Stutz

Human adaptation and niche alike are defined in major part by technology. We use our bodies to shape and transform our material surroundings, fundamentally to extract food resources, but often to create things that we then utilize with our bodies to shape other things, including our own bodies. Technology really changes the way our bodies intertwine with and experience the environment.

Bonobo using a stick as a fishing tool to extract termites in the San Diego Zoo. Photograph by Wikipedia user TacoDeposit, licensed under a CC-BY-SA 3.0 license. It is reshared here under a CC-BY-SA 4.0 International License, acknowledging TacoDeposit’s authorship.

Our tool-using primate relatives–and tool use is quite common in the primate order–mainly employ technologies that are expedient (Bently-Condit & Smith, 2010). Perhaps with the exception of stone hammer-and-anvil nut cracking, observed mainly in some chimpanzee communities (Haslam et al., 2009), primate tool-users do not go out of their way to provision themselves with raw materials or finished, modified tools, as they go about planned foraging tasks over a period of hours. Rather, facing an immediate challenge in extracting food or water, primates take–and sometimes quickly, slightly transform–materials in their immediate vicinity, in order to solve that challenge. This happens in a matter of seconds or minutes. Continue reading Learning about the Protoaurignacian