Article published by HonestThinking 08.06.2010.
I am personally convinced that Michael H. Hart’s book Understanding Human History will be remembered as an important work in the emerging field of biohistory. As I have argued before, I agree with its basic premise that genetic intelligence measured in average IQ tends to rise the further north you get. However, it is strange that the Neanderthals were displaced by more recent African immigrants, even though it has now been proven that the newcomers interbred with them. This seemingly contradicts the cold climate theory for the evolution of high intelligence. We don’t yet know why Homo sapiens sapiens displaced the Neanderthals in northwest Eurasia, where the latter had managed to survive in a challenging climate for tens of thousands of years and had evolved brains that rivaled our own in size.
One possibility is that anatomically modern humans carried a parasite that was relatively harmless to them but dangerous to Neanderthals. Another possibility is that modern humans, who were physically lighter than Neanderthals, consumed less energy while hunting similar prey. A popular, though unproven, hypothesis is that modern humans carried mutations that gave them an edge in social and verbal communications. Whatever the cause, we did replace them so we must have enjoyed some crucial advantage over them. What we know indicates that Neanderthals were never very numerous and had a rather low population density.
In their fine book The 10,000 Year Explosion: How Civilization Accelerated Human Evolution, authors Gregory Cochran and Henry Harpending suggest that a larger population mass and growing population density in itself became a major factor in human evolution by greatly increasing the total number of potential mutations:
Human numbers had already been on the increase since the advent of behavioral modernity, partly as the result of migration into the far northern regions of Asia, over the sea into Australia, and across a land bridge into the Americas – all places that archaic humans had been unable to settle – and partly because of improvements in food production technology (such as nets and bows). An educated guess puts the total population of the world 100,000 years ago at half a million, counting both anatomically modern humans in Africa and archaic humans (Neanderthals and evolved erectus) in Eurasia. By the end of the Ice Age some 12,000 years ago, there may have been as many as 6 million modern humans – still hunter-gatherers, but far more sophisticated and effective hunter-gatherers than ever before. Farming, which produces 10 to 100 times more calories per acre than foraging, carried this trend further. Over the period from 10,000 BC to AD 1, the world population increased approximately a hundredfold (estimates range from 40 to 170 times). That growth in itself transformed society – sometimes, quantity has a quality all its own.
My personal opinion is that the correlation between cold climates and high average IQ is so strong that it is unlikely to be coincidental. Yet there are a few exceptions to this general rule, for example with the Eskimos/Inuits in Arctic North America, who have a lower average IQ than northeast Asians and northern Europeans. One could potentially explain this by saying that America was the last major landmass to be settled by humans and that evolutionary pressures consequently had less time to work there. That still leaves the case of the Sami peoples, or Lapps, who live with their reindeer in Lapland in northern Scandinavia, about as far north as you can get in the European mainland. While there is admittedly a lack of data here I haven’t seen any convincing evidence or indications that they have a higher mean IQ than the Dutch or the Germans, who live much further south. As a matter of fact, the statistics I have seen indicate that the highest mean IQ among European populations is found in north-central Europe, for instance among the Dutch and the Germans and southern Scandinavians.
If we postulate that cold winters triggered evolutionary pressures for high IQ, but this effect could be modified by population density and population mass, we can solve this riddle. The most favorable combination would then be a place with cold winters, but at the same time good enough natural conditions to make possible a relatively large population. This would explain why the Dutch have at least as high IQ as the Lapps and why the Chinese, the Koreans and the Japanese have higher IQs than the Eskimos, who have for thousands of years lived in very cold, but also very sparsely populated northern regions. If we combine these two factors then the correlation between them and observed IQ realities becomes very strong.
This leaves the case of the Ashkenazi Jews, which we can explain by postulating the following: For tens of thousand of years, during most of the time when Homo sapiens sapiens has existed, climate was the major driving force behind our evolution, although not necessarily the only one. Humans adjusted to the natural environment. What has changed during the last 10,000 years is that we have started adjusting to an environment we have created for ourselves. Many life-forms affect their surroundings; humble bacteria and algae have changed the composition of the Earth’s atmosphere, for instance. Yet humans shape our surroundings to an extreme degree. With the rise of agriculture and settled civilization came a new diet, new diseases and new forms of social interaction. This greatly affected and possibly accelerated human evolution, which is the main theme of The 10,000 Year Explosion. Not all of the new mutations affected mentality, but it is perfectly conceivable that some of them did.
Geography still matters, but less so than it did in the past. While 40,000 years ago climate was the overriding factor behind evolution, today it is merely one out of many. Increasingly, our biology adapts to the urban cultural environment we have created for ourselves. Jews constitute an interesting case since they probably developed high IQ in less than 1,000 years during the European Middle Ages and early modern era. Their intelligence during this period rose by maybe as much as ten IQ points, about one per century, which is extraordinarily fast. This happened largely in response to the social environment, not the natural one as had been the case with the northern peoples who accumulated high IQ over tens of thousands of years.
Does this mean that Ashkenazi Jews represent the future of human evolution? Not necessarily. Although their story is remarkable in many ways it happened accidentally; neither the Jewish minority population nor the Christian majority population in Europe planned for this to happen, it just did. By contrast, the future will most likely involve some form of genetic engineering where we will deliberately tamper with our DNA, for better or worse.
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