Aug 26 2008

Neanderthal Intelligence

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Homo neanderthalensis (Neanderthal Man) is our closest cousin, so our fascination with them is understandable. How closely related are we? How did we interact when we shared the planet up until 28,000 years ago? Who was more intelligent? Why are we still here and they are not?

Our image of Neanderthal Man also reflects, even encapsulates, our current ideas about evolution and our recent ancestors. Originally Neanderthal Man was visualized as brutish, hunched over, and dumb – the very icon of primitive (even still reflected in those Geico cave-man commercials). This image reflected our biases more than our science. Over time the facts slowly hammered our image into at least something more physicaly accurate: Neanderthal man was fully upright, they were not necessarily any more hairy than Homo sapiens (us), and they had a brain that was on average larger than modern humans.

But despite their larger brain size, which can reasonably be explained in part by their more robust physical stature, we still clung to our belief in Homo sapien superiority. After all, we are still here and they are not. We won.

The bias that most colored our view of Neanderthal man is the belief that evolution is an inherently progressive process. Evolution, it was believed, led through imperfect and primitive stages until finally achieving its pinnacle in Homo sapiens. But Stephen J. Gould and others spent their careers smashing this image of evolution. Gould argued that evolution is not inherently progressive. It merely adapts species to their local and immediate conditions. Any “progress” is purely an epiphenomenon. Gould’s non-progressivist view of evolution has dramatically shifted the consensus view of how evolution plays out over time, but there are still those who feel (and I think with good reason) that there may be a statistical trend toward something that can meaningfully be called progress at some times in some evolutionary lineages. This remains, as far as I can tell, a point of contention.

At the very least the current view of evolution is that it is not necessarily progressive. And further we must expunge the notion that ancestor species were incomplete and in the process of evolving into their descendants. Rather, they simply were what they were – they were adapted to their environment and weren’t necessarily in the process of becoming anything. Also, almost every species that has ever lived has become extinct – extinction is natural and inevitable. It does not represent inferiority or flaws. It usually just reflects bad luck – and everyone’s luck eventually runs out.

Back to Neanderthals – they were a successful species adapted to the European ice age. Homo sapiens evolved in Africa and then later migrated to Europe and elsewhere. From about 40,000 years ago to 28,000 years ago we shared Europe with the Neanderthals. This certainly sparks the imagination – what would it be like to share the planet with another (even closely related) intelligent technological species? Did we compete with them, trade and interbreed with them, or ignore them?

So far the evidence suggests that we did little if any interbreeding with Neanderthals. So either the Neanderthals simply died out, perhaps as the ice age retreated, or they were out-competed by Homo sapiens, or something else happened. Explanatory biases mentioned above favored the out-compete hypothesis. One line of evidence for sapiens superiority lies in our superior tool kit – we had better stone tools than the Neanderthals. Specifically sapiens were able to craft more slender flint blades while Neanderthals crafted broader blades. It was assumed for decades that the more slender blades were more efficient – they used less resources, created more cutting surface, and lasted longer.

A new study by researchers at the University of Exeter, Southern Methodist University, Texas State University, and the Think Computer Corporation, have found all of these assumptions to be false. They spent three years making flint tools and comparing the results. They found that the Neanderthal stone knife was just as efficient in terms of use of resources, cutting surface, and longevity as the Homo sapiens’ more slender flint knife. The press release gives this explanation of the results:

Now that it is established that there is no technical advantage to blades, why did Homo sapiens adopt this technology during their colonization of Europe? The researchers suggest that the reason for this shift may be more cultural or symbolic. Eren explains: “Colonizing a continent isn’t easy. Colonizing a continent during the Ice Age is even harder. So, for early Homo sapiens colonizing Ice Age Europe, a new shared and flashy-looking technology might serve as one form of social glue by which larger social networks were bonded. Thus, during hard times and resource droughts these larger social networks might act like a type of ‘life insurance,’ ensuring exchange and trade among members on the same ‘team.’”

I love the experimental approach to archeology and challenging these prior assumptions. However, I think they may be premature in concluding that the slender blade had no advantage over the broader blade. What if the blade was a more efficient killing tool? Perhaps it resulted in a higher percentage of kill success in the hunt, allowing Homo sapiens to survive better during lean times or harsh winters, and simply out-compete Neanderthals for food. It does not appear that this hypothesis was tested.

The popular press is presenting this new research as evidence debunking the “stupid” Neanderthals myth. While this is partly true, that is really just an inference from this data – not something in the data itself. There are also other lines of evidence that Homo sapiens possess intellectual capacity lacking in the Neanderthals – most notably the creation of art. Cro-magnon man left behind cave painting and carved figurines. Neanderthals did not leave behind anything that can be called art.

In fact, Homo sapiens also left behind delicately crafted stone tools – probably useless, but highly decorative. They may have done this to show off their skill. So even if the more slender blades (which were functional) were not more efficient in terms of their production, they may have represented superior skill.

The unresolved (and perhaps unresolvable) question is whether the ability and penchant for creating art represented a superior brain or simply culture. Maybe Homo sapiens benefited from the chance birth of a cro-magnon Einstein – a cave-man genius who planted cultural seeds for the Homo sapiens that the Neanderthals lacked.

Other lines of research are also addressing the question of why Homo sapiens survived when Neanderthals did not. For example, evidence suggests that Neanderthal women joined their men in the hunt, while Homo sapiens had a division of labor between the sexes that gave them greater versatility and perhaps was a decisive advantage over the Neanderthals.

Overall this is an excellent study that addresses one specific question regarding the Neanderthal-Homo sapiens debate. It also raises again the larger concept of the dominant character of evolutionary history – is it progressive, just locally adaptive, or what mix of both. But I do not think this new data ends the debate about whether or not Homo sapiens had distinct advantages over Homo neanderthalensis that enabled the former to out-compete the latter.

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