Gregory Cochran and Henry Harpending -- The 10,000 year explosion ================================================================= What I want to know is why this explosion happened to this one specific species. What were the necessary conditions and the enabling factors that caused humans to acquire the intelligence and to produce the tools and to create the social structures that gave them so many capabilities that other species do not have? There are hints about this in "The 10,000 year explosion", and some of them are: - Tools - Spoken language - Written language - The ability to work cooperatively with others. Other animals cooperate also, but language is likely a huge multiplier here. - The ability to share solutions, techniques, and other information with others. This likely started locally, sharing with other family members, then expanded to sharing within a larger group such as a tribe, and later even sharing with unknown individuals and with others in a different place and time. Again, language was probably an enabler. But, each of the above are steps in a progression. So, we can always ask: But, what were the enablers of that step? So, it's likely that we are seeking, not a single cause, but a sequence or cluster of causes along with a story that fits those causes into an explanation. What I'd also like to know is whether there is a possible explanation for differences in creative and innovative abilities and inclinations across cultures. Cochran and Harpending cannot give us any simple answer to these questions about species differences and cultural differences, *but* they have plenty to say that is of interest to those of us who think about them. What Cochran and Harpending do try to describe and explain is how, once these changes started happening, they began happening much more quickly and frequently over the last 10,000 years than previously. And, now we have them happening at a maddeningly fast pace. I'd love a chance to ask Cochran and Harpending whether the very recent speed up in changes (during the last 50 years or 500 years, say) has some genetic basis, too. But, it's important to remember that Cochran and Harpending at least claim to be talking about an acceleration of *evolution*, which implies that they are talking about physical changes in the human species over the last 10,000 years and also about genetic changes (changes in the frequency of certain genetic characters in human populations, and *not* just in changes in the way we think and feel. Cochran and Harpending are also arguing that because of evolutionary changes since the appearance of the human species, separate populations of humans are genetically different. It's easy to be mislead (off the track, into the ditch, etc) while reading this book into thinking about the increased rate at which human societies (especially advanced societies such as the Chinese and the Western European societies since the scientific revolution) have created new inventions. That's one of the things that Cochran and Harpending have to account for, of course. But, it's actually the rate of change of the human species itself that is their focus. And, their book stands up (holds water, is a successful explanation, etc) depending on whether they can show that the rate of change in the human species and the genetic material that, when expressed, characterizes that species has been more rapid in the last 10,000 years than previously. And, "The 10,000 year explosion" must also show that the increase in that rate of change makes a difference. In particular, that this rate of change in our genetic material has important consequence for how we act, the kinds of societies we form, what kind of communication and thinking we are capable of, etc. And so, given my own interest in innovations and inventions, and in what enables or encourages us to do more or less of them, its important to ask whether the changes that Cochran and Harpending discuss, i.e. genetic changes in the human species, can be used to explain the rapid rate of innovation that we see over recent time spans (the last 500 years, the last 50 years, the last 5 years). Another way of expressing this would be to say: (1) Some cultures are more inclined to scientific development, technological innovation, artistic development, etc. (2) Those inclinations are due to cultural differences. (3) Those cultural differences are due to differences in the people that make up those cultures. (4) And, the differences in the people are due to genetic differences, i.e. to differences in the occurrence of genes in the people that make up those cultures. It's an interesting claim. I'm not even sure that it is the kind of claim that could be supported by research, because of the lack of hard, direct, clear connections between frequencies of genes in a gene pool, the complex expression of those genes in individuals, and the behavior of individuals across cultures. So, in contrast, I'm much more inclined to believe that the tendencies of a society to produce innovations is much more the result of influences like education, socialization, rewards and incentives within the society, infrastructure and support systems within the society, etc. However, in spite of my inclination in the direction of nurture over nature (cultural influences over genetic ones), the chapter of "The 10,000 year explosion" titled "Medieval evolution: how the Ashkenazi Jews got their smarts" is well worth reading because it focuses on differences in IQ (and other differences as well) across populations. And, it's easy to imagine that those differences might result not just in differences in ability, but also differences in inclination, motivation, etc across cultures. That chapter is also interested because it discusses some of the ways in which genetic changes happen, and how those changes pass along genetic information in neighboring DNA. (For more on selective sweeps and genetic hitchhiking, see http://en.wikipedia.org/wiki/Selective_sweep. Cochran and Harpending lean heavily on *sweeps* in their descriptions, although I can't see that they explain that concept directly. And, if you are interested in human history at a broader level than who won what battles, you will want to look at the chapter titled "Gene flow". It describes so of the mechanisms by which alleles (genetic alternatives) have spread across regions and populations. If you are interested in these kinds of ideas and questions, then I'd also recommend: (1) "The Blank Slate: The Modern Denial of Human Nature" by Steven Pinker and (2) "Paleofantasy: What Evolution Really Tells Us about Sex, Diet, and How We Live" by Marlene Zuk. 09/18/2014 .. vim:ft=rst:fo+=a: