milk and human sociobiology

Gerold Firl (
21 Jan 1997 21:25:59 GMT

I am interested in the evolution of dairying, both as a cultural
process and a biological one. In fact, this is a perfect example of a
process which can *only* occur as a synchronous socio/biological
evolution, where people learn how to use their domesticates as dairy
animals and integrate new customs into the culture, while at the same
time spreading the genes for adult lactose tolerance throughout the
population. I'm wondering how well that process is understood; I
haven't seen much comment in the literature.

Based on the limited extant of lactose tolerance among human
populations (concentrated among speakers of IE, semitic, and
nilo-saharan languages) it appears that lactose toleration became
an adaptive trait fairly recently. Campbell cites tentative dates of
3500-4000 bc for polychrome mosaics of the milking, straining, and
storing of milk at the temple complex of Obeid in iraq; this is the
earliest evidence of dairying that I am aware of. Has the dating been
refined? And does evidence of earlier dairying exist?

Here is an interesting question: did the genes for lactose tolerance
diffuse outward from a single source, or did evolution locally select
for it in areas where cattle were kept for meat? Actually, both
processes undoubtedly occured, but which was faster?
