Tag Archives: anthropology

Smoking, diabetes and Neanderthal ancestry

Neanderthals_-_Artist's_rendition_of_Earth_approximately_60,000_years_ago

Though they went extinct about 30,000 years ago, Neanderthals are making big news these days. Thanks to recent advances in gene technology, scientists(Sriram Sankararaman and others) now have access to a fuller, more accurate Neanderthal genome. This allows scientists to give a more definitive answer to the age old question “how much did modern humans and Neanderthals interbreed?” Apparently, a lot more than what was previously thought.

For decades, it was assumed that the ancestors of modern humans and Neanderthals didn’t interbreed, or that if they did, Neanderthal genes were selected out. Now it looks like some interbreeding did take place in Eurasia, but not in Africa. Hence, caucasians and east Asians have traces of Neanderthal genes, while black Africans do not. Whether or not Neanderthals were a separate species or sub-species of human is a controversial issue among anthropologists, and is beyond the scope of this post.

It is estimated that about 2% to 4% of the genetic blueprint of non-Africans is derived from Neanderthals, with east Asians having slightly more. Interestingly enough, these genes appear to be partially responsible for diabetes, Crohn’s disease, and even difficulty quitting smoking among modern humans. If you suffer from one or more of these issues, you may be understandably upset that at least one of your ancestors married a Neanderthal.

Then again, Neanderthal genes may also have their advantages, like coding for thicker, cold-resistant skin. Also, the genes that play a role in disease or addiction today may have been helpful thousands of years ago. Red hair in humans may have first evolved among Neanderthals, so if you love your red hair, this may be due to Neanderthal ancestry.

Neanderthals were also generally shorter, and had bigger skulls than the Homo sapien invaders from Africa. The specific reasons why the Neanderthals went extinct is still something of a mystery – the idea that they were “dumb” doesn’t hold much water. We know they were out-competed, but we don’t know why exactly.

Maybe these recent discoveries will lead to a split within the Paleo diet movement: those who are more Neanderthal can eat one way, while those who are more Homo sapiens can eat another. It is well-known that Neanderthals were generally big meat-eaters, while early modern humans ate a more diverse diet.

As both science and technology continue to advance, we can expect many more startling revelations about human origins. I would personally love to see better research on early human and early chimpanzee interbreeding, especially the last times humans and chimps ever successfully interbred and what genes, if any humans got from chimpanzees. Unlike more recent Neanderthal-Homo sapien interbreeding(tens of thousands of years ago), early human-chimpanzee interbreeding likely took place more than a million years ago, so it may be difficult to find reliable DNA specimens, among other limitations.

BBC News – Neanderthals gave us disease genes

Neanderthal genes helped modern humans evolve, studies suggest

Can’t Quit Smoking? Try Blaming Neanderthals

Fifth of Neanderthals’ genetic code lives on in modern humans

Wider headed men are more aggressive

Skull dimensions predicting behavior? It sounds like debunked 19th century criminal anthropology, but hold on. Here is some evidence from the Department of Psychology, Brock University:

Facial characteristics are an important basis for judgements about gender, emotion, personality, motivational states and behavioural dispositions. Based on a recent finding of a sexual dimorphism in facial metrics that is independent of body size, we conducted three studies to examine the extent to which individual differences in the facial width-to-height ratio were associated with trait dominance (using a questionnaire) and aggression during a behavioural task and in a naturalistic setting (varsity and professional ice hockey). In study 1, men had a larger facial width-to-height ratio, higher scores of trait dominance, and were more reactively aggressive compared with women. Individual differences in the facial width-to-height ratio predicted reactive aggression in men, but not in women (predicted 15% of variance). In studies 2 (male varsity hockey players) and 3 (male professional hockey players), individual differences in the facial width-to-height ratio were positively related to aggressive behaviour as measured by the number of penalty minutes per game obtained over a season (predicted 29 and 9% of the variance, respectively). Together, these findings suggest that the sexually dimorphic facial width-to-height ratio may be an ‘honest signal’ of propensity for aggressive behaviour.

This was only true of men, not of women. And yes, I realize “on average”. It looks like testosterone makes the skull wider, and so the higher a man’s testosterone levels, the wider his skull. And we all know testosterone is partially responsible for aggressive tendencies. A little more info: Facial structure is a reliable cue of aggressive behavior.

This is very interesting research. Hopefully the experts will do even more research, but I often wonder if there is anything useful that can be done with this kind of information without being discriminatory?