Re: milk and human sociobiology

debra mckay (
Thu, 23 Jan 1997 19:03:45 GMT (Robert Snower) wrote:
> (Gerold Firl) wrote:
>>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?
>To me the more interesting question is, why did the lactose
>intolerance develop? And when? And why was it adaptive?

You have it backwards. Lactose "intolerance" is the *normal* mammalian
condition. Humans who can digest milk after weaning are the oddballs.
It is closely related to the rise of dairy farming; as a mutation it
was probably neither harmful nor beneficial as far as differential
reproductive success goes, but certainly valuable in a cultural context.

It is only a certain Eurocentric bias that leads us to assume that not
being able to digest milk is somehow strange. The vast majority of humanity
now and in the past has managed very well, thank you, not being able
to drink milk once it wasn't necessary to do so (i.e. after about 4 years
of age).


>Best wishes. rs