h2g2 The Hitchhiker's Guide to the Galaxy: Earth Edition

Intriguingly, peoples of different ethnicities have difgferent types of ear wax. Thus Asians have ‘dry earwax’ in which the lipid content is very low – barely 20% – so most of it is made up of keratin and other waste. The rest of the world (Europeans, Americans) produces ‘wet earwax’, where the lipid content reaches 50%. The dry earwax trait is encoded on a recessive gene, whereas the wet earwax phenotype is dominant. Populations which inherit two dry earwax alleles – for the great majority, the Chinese and the Koreans, produce dry earwax. They produce very little cerumen because of pumps which are not so efficient as their wet earwax counterparts.

Such a phenotype is very informative in population genetics and has been used by anthropologists in the tracing of human population migrations, for example, of the Inuit. Indeed, the recessive trait seems to have arisen in North East Asia from where it spread further East still. Intriguingly, North American Indians are also the bearers of dry earwax. Though in the light of human migration towards the Americas via Asia and the Bering Straits thousands of years ago, this hardly seems surprising.

One explanation as to why some human populations have dry earwax whilst others have wet earwax concerns climate change. As humans migrated towards the North and the East, the climate became gradually colder. A core of compact wax might have kept our ancestors’ ears from freezing. The choice of wax versus powder may also have something to do with sweat glands. Cerumen glands are in many ways similar to our axillary sweat glands. And not only are they similar but they also seem to be related. In colder climates, it is imperative to find ways of losing less heat. And one effective way is to stop sweating. Selectivity could have operated on the axillary glands as humans migrated towards the cold, and it may be that such selective pressure ultimately had an effect on the cerumen glands.

that is actually fascinating, Big Al. and i'm not being sarcastic in the least.

lml. (It wouldn't even have occurred to me that you were being sarcastic.)

I often write information to the end of my Entries that I want to remember.

back atcha, Big Al. In real life, i often get accused of not sounding sincere, even when i really am. I dont know why that is.

One of these days, i'll find something i want to write about, that hasnt been done before.

'tell you the truth, the main reason I wrte Entries at all is to put together info I want to remember. I have quite a large collection of encylopaedias at home. I can't dispose of any of 'em because they each contain different/extra pieces of information. For example one has an Appendix containing brief biographies of characters from English literaturew, which isn't in any of the others. For a while, I considered tearing pages out to recreate one giant encyclo. to my on specifications. For obvious reasons, I dismissed that idea due to its obvious impracticalities. Using hootoo, I can write my own Entries containing the info I'm interested in, with the added advantage that it can also be accessed by other people.
I'll probably get around to updating 'Earwax' so its use for tracing human migrations is within the main text