Blind testing

A interesting new study lends support to Darwin's suggestion that certain facial expressions might be inherited:

BBC: Facial expressions 'hereditary'

The faces we pull when we are happy, sad or angry may be passed from generation to generation, according to researchers.

An Israeli team discovered facial expressions among family members bore striking similarities.

Writing in the Proceedings of the National Academy of Sciences, they said their findings suggested expressions may be hereditary.

I must admit, on reading the headline of this story, my natural scepticism kicked in: "Yet another dodgy identical-twins-separated-since-birth study, no doubt," I thought.

At face value (no pun intended), studying identical twins who have been separated since birth is perhaps the best way of distinguishing genetic human traits from environmental ones. Such twins do, after all, have an identical genetic makeup, but have been brought up in different environments. But anyone who has read the late Stephen Jay Gould's excellent (and wonderfully named) book The Mismeasure of Man knows that separated-twin studies aren't all they're cracked up to be. For example, twins separated at birth are typically placed with adoptive parents from similar social (i.e. environmental) backgrounds. Furthermore, the problem of finding enough separated-since-birth identical twins to yield meaningful scientific results encouraged one eminent psychologist studying the heritability of intelligence to, quite frankly, invent whole sets of fraudulent data (obtained with the help of two imaginary research assistants).

But, it turns out, the new facial expressions study does not rely on separated identical twins. Instead, the scientists studied 21 volunteers who have been blind since birth, and compared their facial expressions with those of their relatives. The reasoning was that blind people can't have learnt their facial expressions by watching their relatives (i.e. through their environment), so any unusual facial expressions they share with their relatives might well be genetically influenced). Pretty clever, really.

It might, of course, still be argued that blind people might pick up facial expressions from feeling the faces of their relatives, but this is an interesting new approach to trying to separate genetic from environmental factors (which also lends a whole new meaning to the phrase blind testing). But, at the end of the day, I still tend to side with my favourite Canadian novelist, the late Robertson Davies: Nature and nurture are inextricable; only scientists and psychologists could think otherwise, and we know all about them, don't we?

Writer and photographer Richard Carter, FCD is the founder of the Friends of Charles Darwin. He lives in Hebden Bridge, West Yorkshire.WebsiteFacebookTwitterNewsletterBooks
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