Wednesday, March 3, 2010

Culture, evolution, eugenics, and the nature of people

There was a story in the NYTimes yesterday that reports on work showing that humans have evolved in the context of culture. The story reports culture as an 'evolutionary force' in human evolution. Reference is made to a recent review of this subject in Nature Reviews Genetics.

Humans have evolved in the context of culture -- material, psychological, social, and symbolic. That has of course affected our genes. The ability of adults to digest the milk sugar lactose in populations that have depended on dairying for thousands of years, or of malaria resistance in people whose cleared agricultural fields have provided breeding grounds for mosquitoes are well-known examples. But the phenomenon is much more than that, and indeed is pervasive in humans.

Many aspects of culture protect us from what would otherwise be physical weakness that selection might otherwise have weeded out of our population. Eyeglasses, medicine, social care for the infirm, weapons, social hunting and harvesting and defense, clothing and fire, and the enabling power of language are examples.

Darwin and others worried that the protections of society would lead to the pollution of our gene pool. This was one of the motivating factors of the eugenic movement, as we discussed in a recent post. That movement aimed to remove the 'unfit' (in the Darwinian sense, but often equated to what scientists felt were undesirable in their local social sense).

This is all true and the paper referred to in the news story is a good and informative one that shows how genetic technology has made it possible to find some specific responsible genes, even if one can debate the strength of evidence for some of its examples. But as so often happens with media reports, there is a problem, and the story is misleading in that it seems to suggest that the molding effects of culture are recent (say, post-agricultural), or enumerable (only a few traits molded that way), or that this is a new discovery.

Instead, there is nothing whatever new about this except the identification of specific genetic examples. Once again, it's misleading media-hyperbole. A better understanding of human nature, and an antidote to eugenic-like thinking, or ethnocentrism with the problems that causes, would result from the realization that is not at all new to anthropology, that humans have always been, from the beginning of our divergence from common ancestry with chimps and other apes, the cultural species. From upright posture, to opposable thumbs, language, hairlessness, our physical helplessness relative to other species (no claws, fangs, wings, etc.), and so much else, this has always molded our way of life. As CL Brace, a leading anthropologist put it way back around 1970, culture was humans' ecological niche -- culture is why are here. Indeed that was offered as the reason there is only one human species here today--what was called the competitive exclusion principle in population ecology: only one species can occupy any given ecological niche.

Yesterday there was also a BBC story about the ancient nature of human culture, showing that at the time we were emerging as our current species, as long as 100,000 years ago, even art was already with us.

This fact was routinely known to any anthropologist paying attention, perhaps back to the 19th century when the field more or less became a professional one. And it's not exactly that new, either. To pick but one example, we have two recent posts on Ibn Khaldun who recognized our adaptation to environment and culture in the 13th century. Why can't we learn to be more aware of history and less melodramatic about our own time? Maybe it's in our nature to take our own lives and times too seriously -- maybe it gives our lives meaning. Maybe it's just to sell magazines and promote careers.

The protective effects of culture are vital to human existence and evolutionarily adaptive. And they always have been.


Anonymous said...

"seems to suggest that the molding effects of culture are recent (say, post-agricultural)"

But that is precisely what the troubling new 'science' of HBD AKA the euphemistic 'human biodiversity' argues. Specifically, that there are racial, ethnic, and class genetically-based differences in temperament and intelligence and that these differences are responsible for global economic and technological inequality. I don't know if the Laland et al paper can be categorized as HBD.

If HBD has a bible, it is 'The 10,000 Year Explosion' by Cochran and Harpending.

Harpending: "Human races are evolving away from each other. Genes are evolving fast in Europe, Asia and Africa, but almost all of these are unique to their continent of origin. We are getting less alike, not merging into a single, mixed humanity."

John Hawks on the research of Bruce Lahn: "Whatever advantage these genes give, some groups have it and some don't. This has to be the worst nightmare for people who believe strongly there are no differences in brain function between groups."

HBD is not as fringe as its post-WWII predecessors. It includes an apparently growing number of tenured psychologists, biological anthropologists, and biologists and their students.

Review of 10K explosion

Argument for racial differences in personality

Ken Weiss said...

If I understand your comment you've misunderstood mine by 180 degrees. As to whether we're getting more different in different continents, certainly as time goes by if there is not substantial mixing that is inevitable. Since most mutations are unique at the DNA sequence level, what happens in Africa will not be the same as what happens in the Americas. If I look at only a modest number of spots across the genome, I can identify an indegenous persons' continent of origin essentially 100% of the time.

This genetic divergence will continue to increase, as it can't do anything but that.

How much international travel will modify that is unclear and entirely unpredictable. It's hard to believe that even if we don't run out of jet fuel or ship diesel we can blend all together, and it would take so many generations that, given human cultural unpredictability I can't see it stopping--but given populations in the billions it will take til the sun stops shining for large genetic differences to occur (absent selective events like new infectious or chemical plagues).

The key issue here is how much of this is due to natural selection. We know that some of it is. Classic examples include inherited resistance to malaria, and skin color. How much might be due to sexual selection is open to debate, but some of it may be.

Our post, however, was that much of our characteristics as a species (we were not referring to 'race') is due to the fact that, from the beginning, we were culture-bearing and culture-dependent organisms. We were trying to dampen the naive enthusiasm of the typically overstated media story that adaptation to or biological response to culture was somehow new to our species.

One can't rule out regional adaptations to culture (skin color and malaria are mixed stories: malaria may have to do not just with resisting a parasite but also with agriculture and cleared fields, for example). We are skeptical about facile or convenient examples, or post hoc Just-So stories based on here-and-now examples, attempts to support social racism in genetic terms, and so on.