Saturday, September 18, 2010

Spicy food and collectivism: How the brain shapes culture

We are used to thinking of culture as a social factor and not a biological factor. We attribute dispositions such as being individualistic or being collectivist to the country that one was brought up in, but no one has really looked into why certain cultures tend to be that way. An emerging field of research called cultural neuroscience says that cultural values can be shaped by the brain and genes.


For example, in one striking example I read about quite recently, one hypothesis put forth for the reason why Asian people like spicy food was because spices conferred natural bacteria killing properties that was especially important in a humid climate where food went bad. Over time, the hypothesis goes, people who liked spicy food more and ate more spicy food were less prone to stomach diseases that killed the others, thus passing on their genes for the next generation. A similar finding was found when examining lactose intolerance. Lactose intolerance is far more prevalent in certain regions of Asia where the rearing of lifestock for milk is less common. In Europe however, up to 95% are able to digest lactose, and this is reflected in their preference for milk products like cream and cheese.


In this review by Way and Lieberman, they sought to answer the question as to why certain cultures tend towards individualism and collectivism. They reason that because of evolution, genes that change brain function and influence the cultural norms we adopt and we institute are selected for between people born in different regions. For people brought up in one region that was say marked by famine, grouping together and helping one another might have brought about greater survival for the people, hence the genes that promote this thinking get passed on. In a separate part of the world, marked by conflict perhaps, survival would favor people who think for themselves and for their immediate family members. Over time, those different selective pressures would have promoted different social behaviors in different regions.


What mechanisms might have promoted these behaviors? They reviewed work from scientists studying the distribution of several genetic alleles. Previous work has shown that variation in the serotonin transporter gene, a very important neurotransmitter associated with emotion and reward, was associated with individual differences in social sensitivity. People with the short version show greater reaction to social events such as death or birth of children, regardless of whether it was positive or negative. When these scientists studied the distribution of these alleles in different cultures, surprise surprise! They found that the short version of this allele was much more prevalent in collectivist cultures than individualist cultures.



*higher score on individualism collectivism scale indicates higher individualism.


The authors hypothesize that since this allele makes people more sensitive to being socially excluded, it promotes individuals to tend and befriend, leading to a cultural trend of being more collectivist. There's more to read about other such alleles in the review, but seeing as to how this post is quite wordy already, I'll stop here :)




ResearchBlogging.orgSherman, P., & Billing, J. (1999). Darwinian Gastronomy: Why We Use Spices BioScience, 49 (6) DOI: 10.2307/1313553

Way, B., & Lieberman, M. (2010). Is there a genetic contribution to cultural differences? ... SCAN, 5 (2-3), 203-211 DOI: 10.1093/scan/nsq059

8 comments:

  1. That what I was longing for...., excellent article

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  2. so western-centric, your pov. and that makes it both less interesting and less valid. this starts with the assumption at the top, culture, social, biology... that is a western assumption

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  3. re the graph: Rejection of a couple of outliers (Japan, Nigeria) makes the slope far more impressive. However, it's mostly a graph of Europeans vs East Asians so it would be really easy for another effect (e.g. climate, regional history) to creep in.

    re lactose intolerance: The causality cuts both ways. Lactose tolerance makes you more likely to use milk (especially) or dairy generally.

    Interesting, though.

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  4. "since this allele makes people more sensitive to being socially excluded, it promotes individuals to tend and befriend, leading to a cultural trend of being more collectivist."

    That's the positive side - the negative side might be a greater tendency to apply pressure or force (of various kinds) to get people to stay with us and conform to our expectations.

    The positives and negatives are both real aspects of collectivism.

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  5. @dabu thanks :)

    @gregory - afraid I'm not sure what you mean. If your talking about the spicy food hypothesis, the authors have also said that it applies in western countries. So for example countries in South America, nearer the equator, feature more spicy food in their diet compared to North America.

    @David Bofinger -yes Nigeria is a very big outlier there, and I was wondering about that too. Definitely needs to be looked into. The problem of Europeans and East Asians I guess is an unfortunate problem with the Individualism-Collectivism construct that one is aligned more closely (rather simplistically) with Western societies and another with Asian societies. Including more studies of countries that buck this trend might be more informative.

    @chriswaterguy - yes interesting observation :)

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  6. good post ! thanks for sharing with us.

    Spicy Food

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