Ibn Khaldun, Part I: a brief disquisition on memory loss.

We're in a genetic determinism age, when even scientists who should know better are attributing almost any human trait or aspect of society to genes. Darwinian views on the evolution of behavior are rife.

We think this is greatly overstated in two ways. First, traits that are influenced by many genes (typically called 'complex' or 'multifactorial') are also affected by environments (a generic term for all things other than gene(s) one is looking at), and the trait value of an individual is not well predicted from genetic data. Second, many assumptions about what we're 'hard wired' to be like, that is, what we're genetically determined 'for', are short-sighted, based typically on the here-and-now back-strapolated to evolutionary time. Explanatory scenarios are (we think) too often built mainly on speculative Just-So stories.

In the 19th century, leading social scientists clearly knew that culture and society for the most part were to be accounted for in social terms, not genetic or psychological ones. However, the thrill of the evolutionary chase, in a cultural climate that has forgotten the awful determinism of eugenics and is enthralled with molecular reductionism, has led to serious under-training and amnesia in this regard. Geneticists, mainly trained to run high-throughput gear, may perhaps be excused. But not the social scientists who are jumping into bed with the geneticists (we really wouldn't want to spoil the fun of these rolls in the hay if we didn't think they could have serious ramifications).

But this amnesia is nothing compared to the lost memory of one of the first people to notice and clearly understand the role of environment, in this case cultural and physical, on human societal behavior. We have recently learned, again thanks to the BBC, that that person was the 14th century Islamic philosopher and historian, Ibn Khaldun. (This is a program called "In Our Time", and if you don't already know of it, you might give it a try. It is a phenomenal, intelligent program, as an editorial in the NYTimes has recently said. Podcasts or online listening are available)

Khaldun was the first in western thought to develop a general theory of the processes of societal history. His main point was that there are regularities in social structure that are repeated, predictable, and explicable in terms of social environments. History, he said, should be about its essential processes, not just enumerate its unique, local events.

His most famous work is the Muqaddimah, also called the Prolegomenon, written while he was in a 3-year desert retreat and published in 1377AD. Khaldun presents his theory, using what was known of the history of empires and so on at the time, and focusing on details from the historic relationships between the urban dynasties and the desert Bedouins of the region of North Africa known as the Mahgreb, a region he knew intimately from experience. The Muqaddimah was an extended introduction to his much longer work on the details, called the Asabiyya, meaning 'group feeling' or 'social cohesion'.

Humans, being individually frail relative to the rigors of survival, must cooperate. An essential 'group feeling' holds desert society together so this an be accomplished. From time to time, this solidarity is the basis for the formation of sedentary, urban civilizations. These are large, complex and require even more cooperation, because unlike desert society, urban society requires specialists (rulers, officials, tradesmen, craftsmen, and the like). Desert people live economically stark but self-sufficient lives. Urbanites are dependent on their 'infrastructure' as we would say today.

Khaldun shows how urban society, with its royalty and class structure (needed to keep the peace among otherwise contentious people seeking self-interest), becomes sedentary and much wealthier than desert society. People increasingly forget their cultural roots and become lazy, selfish, antagonistic toward each other, and so on. They grow to covet luxury (theirs, or their neighbor's). This requires officials, tax collectors, judges, police, and so on. The rulers become decadent and lose touch with their origins and their responsibilities. After only a few generations (Khaldun says four), the dynasty becomes 'senile'. At its fringes, and due to independent group feelings, a new political movement arises, which displaces the senile dynasty with its own dynasty and the cycle repeats. The Vandals invade and conquer Rome!

The important point in all this for our blog is that this view is one of strong environmental determinism. The same people (that is, the same genotypes) live entirely different lifestyles in all sorts of ways, depending on their physical and cultural environment. One can argue with any of his specific points, but the general picture Khaldun paints is cogent. It is simply an obvious fact that it is the environment, broadly defined, that affects so much of our behavior. The nature and relative amounts of cooperation vs competition, sharing vs sharp dealing, self-protection and risk-taking, and so on are environmentally determined, even if the mix of people includes those with genotypes that may predispose them, relatively, to more or less of a given kind of behavior.

There is of course variation, and that has a genetic component, by which some are smarter than others, or more nervous, or more fidgety. But these are minor variations given the overall patterns of culture, and countless GWAS and other studies have shown how weakly predictable from genotypes are such traits, behavioral, morphological, or disease. And if we can't predict it (at least not yet or without high-level computation), then Nature--in the form of natural selection--would be comparably nondiscriminating.

These are lesson we should learn today: our short-term here-and-now perspective is not trustworthy when it comes to asserting what humans are programmed or evolved 'for'. We have a repertoire of responses that can lead to a wide variety of conditions that, in turn, affect our behavior and our biology.

Khaldun even makes the observation--in 1377!--that some epidemiologists seem to claim to have discovered based on fancy and expensive studies today: sedentary culture with its excess of luxury and dietary overkill leads to obesity and vulnerability to disease. That, in some ways, is a lesson geneticists, driven by vested interests, shunt to the background, despite the obvious fact that it's a major rather than minor factor in public health.

Khaldun explicitly worked from a Galenic point of view. That is, he saw human health in terms of the balance, or lack of it, among the four humours. This of course colored his view and makes some of his writing seem quaint. It is certainly dated, though we should not be complacent in thinking that our present view won't seem comparably dated and quaint a few centuries from now.

He also suggested that the Bedouins were healthy because of their spare, tough life style. Clearly he exaggerated and did not have actual demographic data. At that time, too, he could not consider infectious diseases (microbes weren't known), but given the problem of enough clean water and population densities of cities, such diseases would likely have strengthened his case. That is, the burden of infectious diseases would likely have been worse in cities than in the desert.

We're not lauding a 14th century scholar for having perfect insight that needs no revision today. But we would assert that short-sighted thinking is very costly these days, in terms of objectives we claim to have in regard to health. His observations about political dynasties may have lessons, too. Many would argue that the American global era is coming to an end in part because of our wasteful, lazy, sedentary, and complacent view of the world.

Khaldun made some other remarkable observations about evolution itself nearly 500 years before Darwin and Wallace (though he didn't use that word--at least not in the English translation we have), including discussion of how racial variation was the result of adaptation over time. We'll talk about that in part II, our next post.