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There are two types of earwax, wet and dry. Wet earwax is common in Africa and Europe, while dry earwax is characteristic of East Asian populations. South and Central Asian populations are half wet and half dry. Native Americans tend to have dry earwax. Nicholas Wade of the New York Times reported in January of last year that Japanese researchers have isolated the gene responsible for earwax differentiation. The curious thing is that earwax doesn’t seem to be terribly important to human survival:
http://www.neatorama.com/2006/12/27/earwax-and-evolution/