Saturday, April 10, 2010

Racial differences in digit ratio

John Manning and colleagues have used the ratio of the length of the index to the ring finger (2D:4D) as a proxy measure of in utero exposure to relatively more estrogen and less testosterone. In other words, a long index finger compared to the ring finger is an indicator of "feminization" in the womb, and a comparatively short index is a sign of "masculinization."

 It turns out that there are large ethnic differences in the 2D:4D ratio. Manning is quoted as saying that, "There’s more difference between a Pole and a Finn than a man and a woman." According to the results of one study, "The Oriental Han had the highest mean 2D:4D, followed by the Caucasian Berbers and Uygurs, with the lowest mean ratios found in the Afro-Caribbean Jamaicans." In plainer language, Hans were the most feminized and Jamaicans the most masculine. You can read about a long list of characteristics associated with digit ratio here.

You gotta love citing studies that have Robert Trivers as a co-author.


  1. Anonymous2:50 PM


    My southern Han wife seems to have a highly masculine 2D:4D ratio ... she is feminine in all other ways ...

  2. Anonymous10:00 PM

    I thought Manning said something a bit different in his book.

    Though not especially motivated to study race – and thus apparently never having read any London School work – the empirical studies which he has found or organized have yielded a clear and interesting picture, bringing together Blacks and East Asians (Zulus, Jamaicans, Chinese and Japanese) as high-RFL and distinguishing them from the typically low-RFL Europeans (Polish, Spanish, English and Hungarian – with Germans and Gypsies scoring a little higher, intermediate with Chinese levels). For just what this means (if it replicates), Manning’s readers are left to refer to the book’s earlier claims. But the finding of a marked and allegedly important similarity between Blacks and East Asians will amaze many – and not just Rushton and Lynn. This is particularly because, having started his book by tending to play up the advantages of early testosterone (good for the heart, supposedly),

  3. This suppors rk theory. The hcg surge at pregnsncy reduces testosterone. Larger female ovaries and smaller male testicles means more reproductive effort toward the more important constraint (Women)


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