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Saturday, 30 May 2015

Denisovans, Neandertals, Archaics as Human Races – Anthropology 1.11

Denisovans, Neandertals, Archaics as Human Races – Anthropology 1.11

Hi dear friends and followers, welcome to my blog. Today we will examine the world of Paleontology and their discovery of an entirely different connection of man with other prehistoric species, or a link to a completely different species. Take five and enjoy, thank you

The 2010 discoveries of Denisovans, the 2012 findings of archaic African DNA, and the additional 2012 genetic sequencing of Denisovans–are part of a longer trajectory dating to the discovery of fossil Neandertals. Ever since the fossil Neandertal discoveries in the 19th century, debates have raged about who they were. Were Neandertals direct ancestors to modern humans? A completely different species? Or a sub-species, like a race? And now what should we do with the Denisovans?

Anthropology can now confidently report that Neandertals, Denisovans, and others labelledarchaic are in fact an interbreeding part of the modern human lineage. We are the same species. There has been extensive admixture across modern humans for tens of thousands of years, and at least some admixture across several archaic groups. Neandertals, Denisovans, and other archaics may be the best example of a true human race or sub-species. They are also fully part of the human lineage, with almost all contemporary humans showing genetic admixture with archaics in our genetic signatures.

The most recent findings can help return anthropology to the work done prior to the rise of the replacement hypothesis in 1987-2010. During these decades, researchers increasingly portrayed Neandertals as a completely separate species, an evolutionary dead-end with little or no interbreeding (see section on More Mothers than Mitochondrial Eve). This reached a crescendo in 2007, as prominent anthropologist and paleontologist Ian Tattersall pronounced in the Journal of Anthropological Sciences:

Interestingly, the new Neanderthal skeletal reconstruction . . . suggest[s] that differences in gait existed between Neanderthals and modern humans. In particular, the very broad and short waist would have imparted a “stiffness” to Neanderthal movement that would have made them cut a very distinctive figure on the landscape. The consequent distinctive behavioral signal further reduces the probability that the two kinds of hominid would have shared any elements of a specific mate recognition system, and that any biologically significant level of gene exchange ever occurred between them. (Neanderthals, Homo sapiens, and the question of species in paleoanthropology, 144)

I’ll admit to a bout of childish laughter when we read this in class–the thought of modern humans being turned off by the stiff gait of the Neandertals is pretty funny stuff. It is also wrong. Current studies show genetically significant interbreeding with Neandertals, Denisovans, and possibly other archaics did occur. Milford Wolpoff’s idea that Neandertals should be considered a subspecies or race of humans seems closer to the truth (How Neandertals inform human variation, 2009). Neandertals are distinctive, so distinctive that many would say they were a separate species. Denisovans seem to be in a similar position. These are what races would really look like, not like the relatively minor differences observed in contemporary humans (see section Race Reconciled Re-Debunks Race).
Tattersall’s article opens the larger question of species classification:

How to apportion the large mass of hominid fossils now known into biologically meaningful units has been debated endlessly, and seems set to splinter paleoanthropology for years to come. The negative consequences of this lack of consensus are severe . . . This is bad enough among colleagues . . . but it is nothing short of disastrous when it comes to communicating our science to the public that supports us. (2007:139)

Tattersall is correct about this potentially disastrous communication. But his answer–to say species are like “individuals” and knowing what a species entails is like how judges “claim to know pornography when they see it even if they cannot satisfactorily define it” (2007:140)–may perhaps be even more disastrous than splintered debate.

There is a better way. “Thus, we think formally of a species in terms of reproductive compatibility, with the trait-list as helpful identifiers, rather than as a set of organisms that share a particular suite of attributes” (Marks 2009:237-238).

Anthropology should go beyond the endless definitional debates to show porous species boundaries. There is really no harm in stressing interaction and admixture within and across species lines, welcoming Neandertals and Denisovans into the human family. The public is actually quite interested in these kinds of crossings:

Anthropology should work to undefine species.

Anthropology needs to stress how it is impossible to define species characteristics outside of an environmental context. “There is no formal, species-specific ground-plan hovering in the background, immune from time and change” (Ingold 2006:263). Or, “If evolution has taught us anything, one might think, it is that there is no essence of humanity, no fixed or final form” (Proctor 2003:220).

Thank you very much again, dear friends, for visiting my blog. Please share your thoughts with us, if you will. have a great day. 

ڰۣIn Loving Light from the Fairy Ladyڰۣ

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