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Wednesday, October 21, 2009

Does Evolution Explain Why Some People Are Mean to Strangers?

Does Evolution Explain Why Some People Are Mean to Strangers? Yes, according to some researchers in an article published on the Smithsonian website. If it's published by Smithsonian, it must be right? Right?

Rob Dunn writes in: The Culture of Being Rude.
Recently a group of biologists has offered a theory that they say explains, if not tube socks, then nearly everything else. In a series of high-profile papers, Corey Fincher and Randy Thornhill, both at the University of New Mexico, and Mark Schaller and Damian Murray of the University of British Columbia argue that one factor, disease, ultimately determines much of who we are and how we behave.

Their theory is simple. Where diseases are common, individuals are mean to strangers. Strangers may carry new diseases and so one would do best to avoid them. When people avoid strangers—those outside the tribe—communication among tribes breaks down. That breakdown allows peoples, through time, to become more different.

Differences accumulate until in places with more diseases, for example Nigeria or Brazil, there are more cultures and languages. Sweden, for example, has few diseases and only 15 languages; Ghana, which is a similar size, has many diseases and 89 languages. Cultural diversity is, in this view, a consequence of disease.

Then Fincher and colleagues go even further. Where people are more xenophobic and cultures more differentiated from one another, wars are more likely. Democratic governments are less likely because the tribe or group comes first; the nation and individuals in other tribes within the nation come second. And finally, poverty becomes nearly inevitable as a consequence of poor governance, hostility between groups, and the factor that triggered this cascade in the first place—disease.
Dunn expresses some skepticism using appropriate language but he goes on to describe "data" (correlations, actually) that supports the idea. The tone of the article is quite supportive of the idea that evolution is behind this behavior.

Evolution absolutely requires genes and alleles. There no evidence to suggest that we have an allele that encourages us to avoid diseased strangers. It could be entirely cultural based on the fact that we have a large brain that's capable of reasoning.

Keep this in mind next time I'm mean to you. It may not be my genes that are making me do it. It may just be my brain and my life experience telling me that I should behave that way!

[Hat Tip: a skeptical John Hawks]


  1. Larry: "Does Evolution Explain Why Some People Are Mean to Strangers?"

    Well of course it does! Single celled organisms have no ability to form intent, and so are incapable of being "mean". Humans, OTOH, do have that ability, and so are capable of being mean.

    As to the question of whether it is genetic or learned (which of course, the author didn't raise), such behavior (or the opposite) clearly can be selected for in domestic animals, so the idea that it is genetic is not far fetched. (It's also possible that the *ability to learn* how to deal with strangers in alternate ways could also be genetic.)

    BTW, strangers can do more than just give you diseases. They can steal your food, your mate, your tools, your territory, and/or your offspring. They can even kill you (and/or your friends and family). Plenty of reason to be wary of strangers beside diseases. And if they are strangers, there is less likelihood that acts of kindness would be reciprocated in the future. A more interesting question is why we can be friendly to strangers.

  2. What Divalent said. :-) Xenophobia almost certainly has genetic component - like fear of snakes. And it's common among many species, too (I think).

    For humans, the disease explanation, particularly it being the most important factor, does not sound probable to me. IMHO, whatever causes territorial behavior causes xenophobia. I'd say in most cases territorial behavior is about competition for limited resources.

    Apart from that, one note: both Larry and John speak of "culture" as something that is wholly independent on genes. But let's not forget that culture itself may be a product of genes. For the recent clear cut example, see Mitra's lab recent paper on zebra finches (Nature, 2000, 459(7246):564-568).

  3. "It may not be my genes that are making me do it."

    But then, it would just be my genes responding in kind, so suck it up.

    Seriously though - I can see that there may be something to what he says, specifically how disease affects culture by splitting us into more and more groups, and each culture evolves separately.

    I don't think Dunn was talking about genetic determinism so much as some interesting new links between previously unlinked phenomenon. It might be right, but might be wrong as well.

  4. as Flanders & Swan once expressed it: "Xenophobia, the fear of guests" ever watched a cat being "mean"?