The conclusion of Gregory Cochran and Henry Harpending’s The 10,000 Year Explosion: How Civilization Accelerated Human Evolution (2009) sums up the major hypotheses of the book as follows:
(1) genetic change and evolution have been preconditions for cultural change (one clear example being the expansion of hominid brains that led to speech and advanced tool making), even though cultural change is powerful and can be an independent force;
(2) genetic evolution and cultural evolution can also be inter-dependent, and influence one another in feedback loops;
(3) about 40,000 years ago human beings experienced a creative revolution during the Upper Paleolithic period in both Europe and northern Asia, which was driven by underlying biological and cognitive changes in Homo sapiens outside of Africa through new genes acquired by interbreeding with Neanderthals and possibly other archaic humans (e.g., the Denisovans);
(4) agriculture caused a 10,000 year explosion: it resulted in the acceleration of both cultural and biological evolution from much larger populations with a higher rate of mutation, in the new environments created by agriculture. Farmers evolved to be significantly different from hunter gatherers both in metabolism and cognition.
(5) evolution has continued until the present, because our environments have generally not been stable or static;
(6) biological and evolutionary change in human beings has also been a neglected but crucial driving force of human history, e.g., the epic expansion of the Indo-Europeans owing to their mutation allowing lactose tolerance into adulthood, the European settlement of the Americas, the failure of Europeans to penetrate Africa until the 1880s, and the evolution of the Ashkenazim in Europe (Cochran and Harpending 2009: 225–227).
Cochran and Harpending (2009: 207) conclude by speculating that perhaps even the industrial revolution and the rise of science have underlying biological or evolutionary influences not yet understood.
To sum up, we can also review how genetic/genotypic and hence phenotypic change can be driven in human societies, in accordance with standard principles of Darwinian evolution:
(1) direct adaptation, in which selection acts on individuals with (i) pre-existing individual genetic variation owing to sexual reproduction or (ii) with mutations;
(2) exaptation (some prior adaptation then “re-designed” to solve a different adaptive problem);
(3) as a by-product (or spandrel);
(4) sexual selection;
(5) genetic drift;
(6) genetic change caused by Malthusianism or differential survival rates, or elite reproductive advantage;
(7) genetic change induced by the policies and practices of governments and state-societies;
(8) genetic change induced by founder effects;
(9) unique genetic change induced by extraordinary events (e.g., plague, genocide, an ethnic minority subject to persecution), which might cause bottleneck effects, founder effects, etc.
(10) higher-level group evolutionary changes might be driven by inter-group competition and differences in group fitness (e.g., an analogy from the animal kingdom is evolutionary arms races).
BIBLIOGRAPHY
Cochran, Gregory and Henry Harpending. 2009. The 10,000 Year Explosion: How Civilization Accelerated Human Evolution. Basic Books, New York.
Chapter 7 of Gregory Cochran and Henry Harpending’s The 10,000 Year Explosion: How Civilization Accelerated Human Evolution (2009) is called “Medieval Evolution: How the Ashkenazi Jews got their Smarts,” and looks at the evolution of the Ashkenazi minority within Europe over the past 1,500 years.
The chapter is based in part on earlier work in Cochran, Hardy and Harpending (2006).
The Ashkenazim were a Diaspora Jewish community that was first based in northern France and Germany in the 8th–9th centuries AD, but were descended from a Diaspora community in southern Europe during the Roman empire in which a significant number of the men of the founder population took European wives (Cochran and Harpending 2009: 204–205; Costa et al. 2013).
The Ashkenazim were therefore, by origin, a cline (admixture) of Middle East Jews and some European women. This is still evident today in modern Ashkenazim, who have about 40% European DNA (Cochran and Harpending 2009: 204). However, after the early founder admixture, the Ashkenazim became highly endogamous (that is, marrying only within their group) and genetically isolated (Cochran and Harpending 2009: 205, 219).
From the later Middle Ages the Ashkenazim began moving into Eastern Europe and Russia, and modern Ashkenazim are present in America, Israel and Europe.
In the modern world, the Ashkenazim are significantly overrepresented in certain higher professions requiring a high IQ, such as the natural and social sciences (Cochran and Harpending 2009: 188–190). In particular, while the Ashkenazim are less than 0.2% of the world population, they are about 22% of Nobel laureates (though most are men, as you can easily see here).
Cochran and Harpending argue that this high average IQ was driven by genetic changes in the Ashkenazim over about a thousand years while living as a persecuted minority in Europe.
In essence, their thesis is as follows:
(1) because of vicious and terrible Christian persecution, the ban on usury between Christians and their exclusion from Christian societies, the Ashkenazim were driven into certain professions, such as being merchants, bankers and financiers for much of the Middle Ages, and in Eastern Europe also tax-farmers, toll-farmers, and estate managers and other middle-men for Christian rulers. These professions or trades require a high IQ, and especially a high verbal and mathematical IQ;
(2) the most successful Ashkenazim in their trades tended to have more children who survived to adulthood, because they were affluent, and so they had a greater reproductive fitness than other, less successful members of their own community;
(3) because of the very high rates of endogamy (marrying only within the group), the differential success and higher birth rates of the most successful Ashkenazim, over time, led to a kind of elite reproductive advantage with genetic effects on the general population, which gradually raised the average IQ of the Ashkenazim as a group (Cochran and Harpending 2009: 191–220, 222–223).
The high average Ashkenazi IQ is therefore largely genetic, and the product of an unusual evolution over the past 1,000 years or so. Further evidence in favour of this is that – in Israel with its First World economic development, education and health care system – the Ashkenazim continue to have an average IQ higher than both Sephardic and Oriental Jewish groups, who have had a different evolutionary history (Cochran and Harpending 2009: 212–213).
The by-product of the evolution of high Ashkenazi IQ was probably a number of unusual genetic diseases in the Ashkenazim, such as Tay-Sachs, Gaucher’s disease, familial dysautonomia, and two forms of hereditary breast cancer (BRCA1 and BRCA2). These diseases are about 100 times more common in Ashkenazim than in European populations (Cochran and Harpending 2009: 188), and they are characterised by affecting two specific metabolic pathways, the first of which is probably related to the central nervous system and neuron development, namely, sphingolipid storage disorders (causing Tay-Sachs, Gaucher’s disease, Niemann-Pick disease, mucolipidosis, type IV) (Cochran and Harpending 2009: 214, 220).
As Cochran and Harpending (2009: 190–191) point out, the high average IQ of the Ashkenazim has greatly contributed to modern science, and – in a sense – has changed human history because Western science has been significantly advanced by high IQ Ashkenazi men: we need only think of Albert Einstein, Max Born, John von Neumann, Richard Feynman, Julian Schwinger, Murray Gell-Mann and numerous others who have changed the course of Western science.
The social consequence of a higher average IQ group is that this increases the sheer numbers of the group on the right-hand side of their bell curve distribution: this means that with an average IQ of 100 for Europeans and an average IQ of 110 for Ashkenazim, there will be about 4 per 1,000 Europeans with an IQ greater than 140, but 23 per 1,000 Ashkenazim with an IQ greater than 140 (Cochran and Harpending 2009: 211). In an egalitarian society, this explains why a high-IQ minority group will be highly overrepresented in professions requiring a high IQ. And as Steven Pinker points out in the videos below, this is a straightforward, even banal, scientific explanation which can be used to combat and refute far-right anti-Semitic conspiracy theories. So truth can help counter the modern Far Right, just as biological truths can be used to counter modern SJWs and their unhinged denial of biological gender differences.
Finally, even the Liberal American cognitive scientist Steven Pinker, in an April 2008 lecture, has pointed out that this hypothesis is not unreasonable, and, above all, can be tested, and will be vindicated or falsified soon enough:
BIBLIOGRAPHY
Cochran, Gregory, Hardy, Jason and Henry Harpending. 2006. “Natural History of Ashkenazi Intelligence,” Journal of Biosocial Science 38.5: 659–693.
Cochran, Gregory and Henry Harpending. 2009. The 10,000 Year Explosion: How Civilization Accelerated Human Evolution. Basic Books, New York.
Costa, Marta D. et al. 2013. “A Substantial Prehistoric European Ancestry amongst Ashkenazi Maternal Lineages,” Nature Communications 4.2543
https://www.nature.com/articles/ncomms3543
Chapter 6 of Gregory Cochran and Henry Harpending’s The 10,000 Year Explosion: How Civilization Accelerated Human Evolution (2009) is called “Expansions,” and examines the genetic effects of large-scale migrations of human beings.
History is filled with examples of certain population groups that conquer, migrate into, or spread over large areas and replace other groups, or replace other groups with some mixing.
Cochran and Harpending (2009: 156) accept that cultural and technological advantages have played a large role in the success of such movements, but also contend that sometimes, in important cases, evolutionary genetic traits have also been a factor. In this respect, as in normal evolutionary theory, we must look at group fitness, and not just individual fitness, as factors in human history (Cochran and Harpending 2009: 158).
Three major examples are analysed in Chapter 6: (1) the success of Europeans in the New World, (2) early European attempts to colonise sub-Saharan Africa, and (3) the astonishing success of the prehistoric Indo-European-speaking peoples.
1. Europeans in the New World
The first example Cochran and Harpending point to was the European colonisation and conquest of the New World.
We know that the Native Americans faced a severe group disadvantage caused by differential evolution: namely, their inability to resist or have immunity to new diseases brought by Europeans like smallpox (Cochran and Harpending 2009: 158–159). The HLA gene alleles, in various forms, protect human beings against infectious disease by regulating the nature and strength of the immune system. But the Amerindians had an unusual distribution of HLA alleles – evolved from their distinct evolutionary history in the Americas – and a much weaker immune system, because they were simply not exposed to the same type and variety of pathogens as the farming peoples of the Old World (Cochran and Harpending 2009: 160–161, citing Cavalli-Sforza and Paolo Menozzi 1994). But the weaker immune systems of Amerindians had an advantage in their distinctive environment: they were much less subject to autoimmune diseases than other peoples with stronger immune systems (Cochran and Harpending 2009: 161).
But when Europeans brought infectious diseases such as measles, smallpox, diphtheria, whooping cough, leprosy, and bubonic plague, the consequences for Amerindians were horrific: there is some evidence that the Amerindian population of the New World suffered a stunning 90% fall in just a few centuries – and most of the deaths were caused by exposure to these diseases introduced by Europeans which Amerindians could not resist because of their different evolutionary history (Cochran and Harpending 2009: 162, citing Cook 1998). For instance, while only about 30% of Europeans might die in smallpox epidemics, a shocking 90% of Amerindians would die from the disease (Cochran and Harpending 2009: 167). This terrible series of plagues obviously aided the European conquest of the Americas, and even with superior European technology, was a factor in the success of the Conquistadors.
For example, the conquest of the Incan Empire by Francisco Pizarro was facilitated by a smallpox epidemic (Cochran and Harpending 2009: 163), as described in this video:
As an aside, it’s curious that this documentary based on Jared Diamond’s Guns, Germs and Steel does not explicitly acknowledge the biological and evolutionary implications of the New World epidemics, because the truly terrible and tragic deaths of millions of Amerindians was the result of different kinds of group genotypes and phenotypes between Amerindians and Europeans, and hence different kinds of group fitness, caused by differential, regional evolution.
As late as the 20th century, isolated populations of Amerindians have suffered the same fate: in instances where first contacts occurred between Amerindians and European-descended people in the 20th century the same European diseases have killed 33–50% of the natives (Cochran and Harpending 2009: 167).
The same kinds of biological differences caused terrible epidemics and mass deaths of Australian Aborigines and Polynesians when Europeans invaded or colonised their homelands as well (Cochran and Harpending 2009: 169).
As Cochran and Harpending (2009: 169) emphasise, anybody who refuses to understand the fundamental role of biological differences between human populations as a factor in European conquest of these regions is in effect denying the reality of Darwinian evolution.
2. Europeans and sub-Saharan Africa
Early attempts to conquer or colonise Africa, even just for trading purposes, encountered a severe difficulty: Europeans discovered that the diseases of Africa had a devastating effect on them. The European people in early expeditions, trading missions and settlements suffered an extremely high death rate from Africa diseases which they had not evolved immunity to (Cochran and Harpending 2009: 171). For example, British soldiers in the Gold Coast died at a rate of 50% (Cochran and Harpending 2009: 171). Right up until the early and mid-19th century, a European conquest of Africa – despite the staggering technological and scientific superiority Europeans had – just wasn’t possible in the way that Europeans conquered the New World. The only major area where colonisation worked was South Africa, and this was because of the temperate climate and the difference in the prevalence of diseases.
Once again, the reason was biological, and was simply the lack of immunity and a different evolutionary history: whereas Africans had evolved their immunity to local diseases and pathogens over thousands of years, Europeans had no such immunity.
It was only with the discovery of drug treatment with quinine in the 1800s that Europeans had a defence against falciparum malaria, and, as scientific medicine began to deal with other tropical diseases, Europeans were able to conquer most of Africa from the 1880s (Cochran and Harpending 2009: 173).
2. The Indo-European Waves of Migration
One of the greatest successes of prehistory was the large-scale Indo-European migrations and conquests in which, over thousands of years, Indo-European people of the Yamnaya culture north of the Black Sea, spread out in all directions (Allentoft et al. 2015: 171; Balter and Gibbons 2015).
There was for many years a scholarly debate about the original homeland of the Indo-Europeans with scholars like Colin Renfrew proposing that the homeland lay in ancient Anatolia (Cochran and Harpending 2009: 178). However, it is now widely accepted that the original Indo-European homeland was in what is now southern Russia above the Black sea (Cochran and Harpending 2009: 179).
For example, from 3,000 to 2,000 BC, there was massive Indo-European migration of people from the South Russian steppe into central Europe, and then into northern and western Europe, and now virtually everybody in Europe speaks an Indo-European language. But modern Iranian and Hindi and Urdu – the major languages of the Indian subcontinent – are also Indo-European. The Indo-Europeans probably had a phenotype with brown eyes, pale skin, and taller height (but interbreeding with other population groups has changed this phenotype, especially in India).
The Indo-European language family was so successful that it now has about 3 billion native speakers, or about 50% of the human race (Cochran and Harpending 2009: 174).
We can see the spread of the Indo-European peoples through the spread of their languages, as illustrated (apart from a few minor mistakes here and there) in the video below:
So why were they so successful?
The Indo-Europeans were not only farmers but also cattle herders, and raised cattle, sheep, goats and pigs, and they may have domesticated the horse (Cochran and Harpending 2009: 176). They seem to have had wheeled carts and chariots, at least in the later stages of history.
But Cochran and Harpending argue that the crucial biological trait that the Indo-Europeans had was lactose tolerance into adulthood, caused by the 13910-T allele, which allows the continued synthesis of lactase (an enzyme that digests milk sugar) past chidlhood (Cochran and Harpending 2009: 180–181; Allentoft et al. 2015: 171). This, they argue, was why the Indo-European peoples were so successful and expanded so many times in thousands of years of history.
At the time, most Europeans (and many other peoples of that time) were lactose intolerant into adulthood:
With their lactose tolerance into adulthood, Indo-Europeans could become highly effective dairying pastoralists, as well as farmers, and could actually produce more high-quality food on a given amount of land than other pastoralists (Cochran and Harpending 2009: 181). In effect, Proto-Indo-European pastoralism had great advantages in inter-group competition, and there was a biological basis to this (Cochran and Harpending 2009: 182).
Indo-Europeans could also abandon farming and become mobile pastoralists, a style of life which has clear military advantages, in contrast to sedentary farmers (Cochran and Harpending 2009: 182). Their dairy-rich diet also gave them greater height, and they soon developed a warlike society (Cochran and Harpending 2009: 183).
So, first of all, Indo-Europeans spread all over the steppe near their homelands, and then into Europe, where they had the edge in inter-group competition and in group fitness against the early European farmers (Cochran and Harpending 2009: 184). Indo-Europeans seem to have conquered or displaced many earlier Europeans, but, perhaps more generally, ruled as an elite and imposed their languages on the native populations (Cochran and Harpending 2009: 184). Interbreeding with Indo-Europeans and gene sweeps then allowed modern Europeans to acquire the trait of lactose tolerance (Allentoft et al. 2015: 171).
Indo-Europeans also spread out eastwards into Central Asia, Iran and even into India.
Underlying this astonishing history of success was the mutation, or mutations, that produced their adult lactose tolerance.
Finally, in the years after 2009 (the year The 10,000 Year Explosion was published), much new genetic evidence has emerged from the revolution in the sequencing of ancient genomes from bones and other remains, which has vindicated Cochran and Harpending’s thesis on the Indo-Europeans:
