viernes, 20 de enero de 2012

Into the mind of a Neanderthal



Neanderthals shared about 99.84 per cent of their DNA with us (Image: Action Press/Rex Features)
What would have made them laugh? Or cry? Did they love home more than we do? Meet the real Neanderthals

A NEANDERTHAL walks into a bar and says... well, not a lot, probably. Certainly he or she could never have delivered a full-blown joke of the type modern humans would recognise because a joke hinges on surprise juxtapositions of unexpected or impossible events. Cognitively, it requires quite an advanced theory of mind to put oneself in the position of one or more of the actors in that joke - and enough working memory (the ability to actively hold information in your mind and use it in various ways).

So does that mean our Neanderthal had no sense of humour? No: humans also recognise the physical humour used to mitigate painful episodes - tripping, hitting our heads and so on - which does not depend on language or symbols. So while we could have sat down with Neanderthals and enjoyed the slapstick of The Three Stooges or Lee Evans, the verbal complexities of Twelfth Night would have been lost on them.

Humour is just one aspect of Neanderthal life we have been plotting for some years in our mission to make sense of their cognitive life. So what was it like to be a Neanderthal? Did they feel the same way we do? Did they fall in love? Have a bad day? Palaeoanthropologists now know a great deal about these ice-age Europeans who flourished between 200,000 and 30,000 years ago. We know, for example, that Neanderthals shared about 99.84 per cent of their DNA with us, and that we and they evolved separately for several hundred thousand years. We also know Neanderthal brains were a bit larger than ours and were shaped a bit differently. And we know where they lived, what they ate and how they got it.

Skeletal evidence shows that Neanderthal men, women and children led very strenuous lives, preoccupied with hunting large mammals. They often made tactical use of terrain features to gain as much advantage as possible, but administered the coup de grace with thrusting spears. Based on their choice of stone for tools, we know they almost never travelled outside small home territories that were rarely over 1000 square kilometres.

The Neanderthal style of hunting often resulted in injuries, and the victims were often nursed back to health by others. But few would have survived serious lower body injuries, since individuals who could not walk might well have been abandoned. It looks as if Neanderthals had well-developed way-finding and tactical abilities, and empathy for group members, but also that they made pragmatic decisions when necessary.

Looking closely at the choices Neanderthals made when they manufactured and used tools shows that they organised their technical activities much as artisans, such as blacksmiths, organise their production. Like blacksmiths, they relied on "expert" cognition, a form of observational learning and practice acquired through apprenticeship that relies heavily on long-term procedural memory.

The only obvious difference between Neanderthal technical thinking and ours lay in innovation. Although Neanderthals invented the practice of hafting stone points onto spears, this was one of very few innovations over several hundred thousand years. Active invention relies on thinking by analogy and a good amount of working memory, implying they may have had a reduced capacity in these respects. Neanderthals may have relied more heavily than we do on well-learned procedures of expert cognition.

As for the neighbourhood, the size and distribution of archaeological sites shows that Neanderthals spent their lives mostly in small groups of five to 10 individuals. Several such groups would come together briefly after especially successful hunts, suggesting that Neanderthals also belonged to larger communities but that they seldom made contact with people outside those groupings.

Many Neanderthal sites have rare pieces of high-quality stone from more distant sources (more than 100 kilometres), but not enough to indicate trade or even regular contact with other communities. A more likely scenario is that an adolescent boy or girl carried the material with them when they attached themselves to a new community. The small size of Neanderthal territories would have made some form of "marrying out" essential.

We can also assume that Neanderthals had some form of marriage because pair-bonding between men and women, and joint provisioning for their offspring, had been a feature of hominin social life for over a million years. They also protected corpses by covering them with rocks or placing them in shallow pits, suggesting the kinds of intimate, embodied social and cognitive interaction typical of our own family life.

But the Neanderthals' short lifespan - few lived past 35 - meant that other features of our more recent social past were absent: elders, for example, were rare. And they almost certainly lacked the cognitive abilities for dealing with strangers that evolved in modern humans, who lived in larger groups numbering in the scores and belonged to larger communities in the hundreds or more. They also established and maintained contacts with distant groups.

One cognitive ability that evolved in modern humans as a result was the "cheater detection" ability described by evolutionary psychologist Leda Cosmides, at the University of California, Santa Barbara. Another was an ability to judge the value of one commodity in terms of another, what anthropologist Alan Page Fiske at the University of California, Los Angeles, calls the "market pricing" ability. Both are key reasoning skills that evolved to allow interaction with acquaintances and strangers, neither of which was a regular feature of Neanderthal home life.

There are good circumstantial reasons for thinking that Neanderthals had language, with words and some kind of syntax; some of their technology and hunting tactics would have been difficult to learn and execute without it. Moreover, Neanderthal brains had a well-developed Broca's area, and their DNA includes the FOXP2 gene carried by modern humans, which is involved in speech production. Unfortunately, none of this reveals anything specific about Neanderthal language. It could have been very or only slightly different, we just don't know.

Having any sort of language could also have exposed Neanderthals to problems modern humans face, such as schizophrenia, says one theory which puts the disease down to coordination problems between the brain's left and right hemispheres.

But while Neanderthals would have had a variety of personality types, just as we do, their way of life would have selected for an average profile quite different from ours. Jo or Joe Neanderthal would have been pragmatic, capable of leaving group members behind if necessary, and stoical, to deal with frequent injuries and lengthy convalescence. He or she had to be risk tolerant for hunting large beasts close up; they needed sympathy and empathy in their care of the injured and dead; and yet were neophobic, dogmatic and xenophobic.

So we could have recognised and interacted with Neanderthals, but we would have noticed these significant cognitive differences. They would have been better at well-learned, expert cognition than modern humans, but not as good at the development of novel solutions. They were adept at intimate, small-scale social cognition, but lacked the cognitive tools to interact with acquaintances and strangers, including the extensive use of symbols.

In the final count, when Neanderthals and modern humans found themselves competing across the European landscape 30,000 years ago, those cognitive differences may well have been decisive in seeing off the Neanderthals.


Profile

Thomas Wynn is a professor of anthropology and Frederick L. Coolidge is a professor of psychology at the University of Colorado, Colorado Springs. For the past decade they have worked on the evolution of cognition. Their new book is How to Think Like a Neandertal (Oxford University Press, 2012)
http://www.newscientist.com/article/mg21328470.400-into-the-mind-of-a-neanderthal.html?full=true

http://www.newscientist.com/article/mg21328470.400-into-the-mind-of-a-neanderthal.html?full=true

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