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January 26, 2004

Days of Ice & Awe

A group of scientists claims that multiple factors (via Dienekes) led to the extinction of the Neandertals. The title in The New Scientist asserts that the "Big chill killed off the Neanderthals." But upon closer reading, it seems that the arrival of a new human culture (Gravettians) and the concomitant cultural explosion swept aside a very low basal population of Neandertals, and, the Aurignacians! As noted in the article, it is latter point is interesting, because the Aurignacians were anatomically modern humans, and creators of the famous cave art that indicates a qualitative change in our cultural history. Nonetheless, the article indicates that the Neandertals and Aurignacians co-existed in diminished numbers until the arrival of the new toolkit.

The moral of the story is that first aproximations always hide a great deal of nuance and subtlety. This research might be unsupported by later studies, but let us assume it is correct. The idea that there was a "Great Leap" 40,000 years ago in mental capacities of human beings that allowed them to engage in symbolic abstraction and consciously develop new and innovative cultural motifs is seductive. Researchers, assuming that language was a crucial part of this leap, are already on the hunt for genes that might have arisen during this period and altered our hardware so that it could run more powerful software. Anthropologist Henry Harpending asserts that the "Great Leap" did not seem to impact the material culture of all anatomically modern humans at the same time (a series of hops, not a leap?).

I also believe that the recent history of our species, especially since the period from around 500 BCE, might have instilled in us preconceptions of the Eternal March of Human Progress that allows us to disregard possible epicyclic deviations from the arrow of change. For instance, Tasmanian Aboriginals, isolated from the mainland for 10,000 years, suffered degredation in their toolkit. The Bronze Age Greeks and Indians both forgot their native literate traditions after socio-cultural decline, and literacy was revived through cultural diffusion from the Middle East. Joseph Needham documented the engineering genius of the Chinese civilization, but he also noted that some discoveries were left fallow, and mechanical wonders forgotten, only to be re-introduced by Europeans!

The Out-of-Africa scenario that posits an expansion of modern humans ~50,000 years ago is seductive in its parsimonious elegance. The genetic evidence points to some form of this. Nevertheless, I think that the simplistic beauty of this model has convinced some anthropologists & paleontologists to brush aside the details in specific locales and points in history and pre-history.

Back to the thrust of the above article. The modification of the "standard model" of Neandertal extinction is not extreme, instead of extreme climatic conditions + the presence of modern humans facilitating the demise of the Neandertal, climatic conditions + the presence of a modern human subculture might be the root cause. But the implication is that the "Great Leap" was just the first step, that human cultural superiority was not created ex nihilo from the DNA.

Posted by razib at 01:53 PM