Earwax and breast milk

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Miura, Yoshiura, Miura, Shimada, Yamasaki, Yoshida, et al. A strong association between human earwax-type and apocrine colostrum secretion from the mammary gland. Human Genetics.

Here we provided the first genetic evidence for an association between the degree of apocrine colostrum secretion and human earwax type. Genotyping at the earwax-type locus, rs17822931 within the ABCC11 gene, revealed that 155 of 225 Japanese women were dry-type and 70 wet-type. Frequency of women without colostrum among dry-type women was significantly higher than that among wet-type women (P < 0.0002), and the measurable colostrum volume in dry-type women was significantly smaller than in wet-type women (P = 0.0341).

Related from Razib: Here are two posts from me on earwax distributions worldwide.

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  1. Two distinct genetically determined types of earwax are distinguished — the wet type, which is dominant; and the dry type, which is recessive. Asians and Native Americans are more likely to have the dry type of cerumen (grey and flaky), whereas Caucasians and Africans are more likely to have the wet type (honey-brown to dark-brown and moist).[3] Cerumen type has been used by anthropologists to track human migratory patterns, such as those of the Inuit.[4] 
    The difference in cerumen type has been tracked to a single base change (an SNP) in a gene known as “ATP-binding cassette C11 gene”. In addition to affecting cerumen type, this mutation also reduces sweat production. The researchers conjecture that the reduction in sweat was beneficial to the ancestors of East Asians and Native Americans who are thought to have lived in cold climates.[5] 
    Ahh…wikipedia. Or, in this case, answers.com

  2. OK…I think I used to have the “wet type,” but now it seems to be primarily the “dry type.” At the risk of too much information, is there anyone else out there like this? 
    I’m turning Japanese, I really think so.

  3. I have dry, flaky earwax – yet sweat like a horse?!

  4. That would be the Jewish ancestry. 
    Standard moist brown earwaxer, me.

  5. I initially regarded this with a certain amount of amusement, but with Ogler’s helpful supplement and Razib’s addition to the original post it begins to look more interesting. 
    To add to the collective database: 
    Me (Western European ancestry) – moist brown earwax, sweaty. 
    Wife (Northern Han Chinese) – dry pale earwax, sweats very little. 
    Daughter (visually very obviously a mix of wife + me) – dry pale earwax, sweats very little.