A new paper challenges this prevailing view of the onset of behavioral modernity.
Here is what appears to be a dated quote from the paper:
I would say that the recent 2010 articles on Neandertal/Denisovan intermixture with modern humans makes the notion of Neandertal irrelevance problematic. Indeed, while the author of the current paper argues for behavioral variability in anatomically sapiens populations predating the "Upper Paleolithic Revolution", I would say that an equally important aspect of variability is that related to non-sapiens populations such as Neandertals. That is, we should question not only the exclusion of chronologically older sapiens populations from behavioral modernity, but also contemporaneous non-sapiens ones.
Yet fossil morphology combined with studies of DNA both from fossils and from living humans now shows that Neanderthals and their associated archaeological record are largely irrelevant for models concerning early phases of H. sapiens evolution (Harvati, Frost, and McNulty 2004; Serre and Paabo 2006).
Shea is dismissive of the Neandertal intermixture hypothesis, stating that:
Whatever one thinks about this issue, it is simply a fact that during the period under discussion, 50–200 kya, H. sapiens was an African primate.
I am not so sure about that. We have evidence for ~100ky anatomically modern humans in China, Arabia, the Levant (Qafzeh), and North Africa. A quite recent genetic study discounts the recent Out of Africa paradigm, opting instead for either a Multiple Archaic populations model, or an ancestral bottleneck 150 thousand years ago in Africa.
A significant part of the paper's argument is focused on the occurrence of different lithic technologies across time and space in Africa. The argument, as far as I can understand it, is that Mode 5 microlithic technologies of the European Upper Paleolithic type do not represent an innovation worthy of an idea of "progress" or particular newly-hatched cognitive skills:
Microlithic technologies occur in African contexts sporadically between 50 and 100 kya (Ambrose 2002). They become common and widespread after 20 kya, not just in Africa but also in Eurasia (Elston and Kuhn 2002). However, one ought not read too much into this difference. Small retouched stone tools are known from many Eurasian Lower and Middle Paleolithic contexts (Dibble and McPherron 2006; Zaidner, Ronen, and Burdukiewicz 2003). Small geometric-backed pieces are known from Last Interglacial (presumably Neanderthal) contexts in Germany (Conard 1990). Whatever cognitive capacities mode 5 microlithic technologies require were plainly ones that were either evolutionarily primitive or evolved convergently in the genus Homo.
While Shea questions the behavioral non-modernity of early East Africans such as Omo, Schwartz and Tattersall question the label of "archaic Homo sapiens", suggesting that recent Homo sapiens (of the period of the "Upper Paleolithic Revolution" and recent humanity) can be anatomically defined in a manner excluding of these earlier hominins. Another recent study gives me no great confidence that Rhodesian Man (Kabwe) commonly identified as ancestral to the Omo "archaic sapiens" deserves that position.
So, should we extend the definition of sapiens in both its anatomical and behavioral aspects to 200ky East Africans, or should we limit it (per S&T's suggestion) in both senses to humankind of the last few tens of thousands years?
My personal preference, stated several times in this blog, is to think in terms of a recent demographically dominant "Afrasian" population that absorbed other archaic humans in Africa ("Paleo-Africans") and Eurasia (Neandertals/Denisovans/?).
Recent genetic evidence (every time we sampled an "archaic" hominin we found that it can't be fit to a pure Out of Africa model) suggests to me that intermixture between deeply divergent human populations was the norm, rather than the exception, and assimilation models, or even multiregional evolution may be true, the latter.
As for the onset of "behavioral modernity" I envision two scenaria:
- An accretion of genetic changes across interbreeding hominins across the globe led to a demographic explosion, which led to more beneficial mutations in the ever-larger human population, which led to an even more successful human population (in both the behavioral and demographic senses)
- A cognitive leap allowed a portion of Homo (the Afrasians) to multiply, expand, and dominate over all other hominins, absorbing them in the process.
Whether one questions the concept of behavioral modernity or not, I think it's undeniable that something happened ~50ky ago leading to the extinction (via assimilation or competition) of so many not-modern looking populations across Eurasia.
Vol. 52, No. 1 (February 2011), pp. 1-35
Homo sapiens Is as Homo sapiens Was
John J. Shea
Paleolithic archaeologists conceptualize the uniqueness of Homo sapiens in terms of “behavioral modernity,” a quality often conflated with behavioral variability. The former is qualitative, essentialist, and a historical artifact of the European origins of Paleolithic research. The latter is a quantitative, statistically variable property of all human behavior, not just that of Ice Age Europeans. As an analytical construct, behavioral modernity is deeply flawed at all epistemological levels. This paper outlines the shortcomings of behavioral modernity and instead proposes a research agenda focused on the strategic sources of human behavioral variability. Using data from later Middle Pleistocene archaeological sites in East Africa, this paper tests and falsifies the core assumption of the behavioral-modernity concept—the belief that there were significant differences in behavioral variability between the oldest H. sapiens and populations younger than 50 kya. It concludes that behavioral modernity and allied concepts have no further value to human origins research. Research focused on the strategic underpinnings of human behavioral variability will move Paleolithic archaeology closer to a more productive integration with other behavioral sciences.