Dean Esmay asked about the timescale of the origins of milk-drinking. Here
is some information from a paper by Frederick J. Simoons (1988) "The
Determinants of Dairying and Milk Use in The Old World: Ecological,
Physiological, and Cultural," In JRK Robson (ed.), Food, Ecology and
Culture: Readings in the Anthropology of Dietary Practices. New York:
Gordon and Breach. (pp. 83-91)

First a few statistics about modern milk tolerance:

- 70% of the world's population is lactose-intolerant. This figure includes:
- 90-100% of Asians.
- 75% of African-Americans.
- 80% of Native Americans.
- 50% of Hispanics worldwide.
- 20% of Caucasion-Americans.

[taken from: Mogelonsky, Marcia (1995) "Milk Doesn't Always Do a Body
Good," American Demographics, Jan. 1995 issue.]

Babies are born with the capacity to digest the lactose in milk via
production of the digestive enzyme lactase. Starting around 3-4 years old,
however (if I am remembering correctly), this capacity is normally lost.
This would have been the baseline *normal* state of affairs prior to the
advent of agriculture.

The 30% of the world's population that does not exhibit adult lactose
intolerance can trace its heritage very closely to the earliest populations
of humans that began the practice of herding animals for their milk. The
earliest milking populations in Europe, Asia, and Africa began the practice
probably around 4,000 BC. Simoons says:

"The distributional pattern and historical record of milking and nonmilking
in the Old World suggests that the milking habit developed somewhere within
the Eurasian-African landmass and spread outward. The earliest convincing
evidence we now have of milking is for the Sahara Desert, during the middle
of the so-called Pastoral Period (circa 5500-2000 BC) of the Neolithic.
[Elsewhere Simoons puts the best-estimate date at approx. 4000 BC.] At that
time the desert was somewhat rainier and able to support pastoralists,
whose most prominent animals were common cattle. The pastoralists'
abundant, naturalistic rock drawings, reminiscent of Lascaux and Altamira
in Europe, include clear milking scenes. We cannot, however, be certain
that the milking habit originated in the Sahara; whether, as many scholars
suspect, it originated somewhere in Southwest Asia, or whether it developed
elsewhere."

Simoons goes on to delineate the world's lactose-intolerant populations
today, saying:

"Of special significance are the world patterns of high and low incidence
of primar adult lactose malabsorption, for these bear a considerable
similarity to the traditional patterns of milking and nonmilking sketched
previously. For example, many groups with a high prevalence of such
malabsorption, have traditionally been nonmilking. These include Greenland
Eskimos, various American Indian tribes, American-born Negroes and
Orientals, Yoruba and Ibo in Southern Nigeria, Bantu agriculturalists of
the Congo, Bushmen, Chinese, Japanese, Thais, Indonesians, Filipinos,
native Fijians, Australian aborigines, and natives of New Guinea. Indeed,
all groups tested so far whose origins lie in the traditional zone of
nonmilking have high prevalences of primary adult lactose malabsorption. Of
the groups found to have low prevalences of such malabsorption, moreover,
all seem to come from long backgrounds of consuming abundant dairy products
in lactose-rich forms. These include Danes and certain other northwest
Europeans, their overseas decendants in the Americas and Australia, the
pastoral Fulani of Nigeria, the Hima and Tussi of East Africa, Bedouin and
other Saudi Arabs, and various groups in the northwest of the Indian
subcontinent. Differences in the prevalence of primary adult lactose
malabsorption are particularly striking in the United States, whose people
are quite varied in the ethnic and racial origins."

After a lengthy analysis, Simoons concludes, "The strong suggestion is that
we are dealing with a genetic condition, that primary adult lactose
malabsorption is the normal state in animals and man, and that selection
for high group prevalence of absorption has developed during a long history
of using lactose-rich dairy products." [i.e., only in those populations
with a history of it]

One estimate of the time needed for lactose tolerance to become the norm
rather than the exception in a population where milk-drinking is regular is
that it could occur in as little as 1,150 years in populations with
sufficiently strong cultural pressures for it [Cavalli-Sforza et al 1994
"The History and Geography of Human Genes. Princeton, NJ: Princeton Univ.
Press. p.13]. For Northern Europeans, there is research showing the
prevalence of lactose tolerance developing from 5% to approx. 70% in about
250 generations (roughly 5000 years).
[Aoki K. (1991) "Time required for gene frequency change in a deterministic
model of gene culture coevolution, with special reference to the lactose
absorption problem. Theoretical Population Biology vol. 40, pp.354-68.]
(Thanks to Loren Cordain for pointing out this latter reference to me.)

However, lactose tolerance is probably only one among a number of
adaptations that would have to occur for full adaptation to the consumption
of other animals' milk products to take place without health repercussions.
(Dean mentions the casein and lactoglobulins in animals milk differ
substantially from human milk, for example.)

Perhaps Loren might expand on other troubles with milk, prominent among
them, the calcium/magnesium ratio, I believe, which he mentioned to me
briefly in a separate conversation. Basically the situation as I recall it
is that in the Paleolithic diet the Ca:Mg ratio is approx. 1.0. In milk and
dairy products the ratio is 12.0, and can skew the overall dietary ratio to
4.0 when added to the usual American diet. (How it would affect the overall
ratio in an otherwise Paleolithic diet I am not sure.) Loren, perhaps you
could go into the health repercussion of excessive calcium relative to
magnesium?

I might add here that an interesting side-question I have not seen answered
to my satisfaction is whether despite such problems, dairy products in
moderation might prove of some help in other ways to those who eschew meat
(i.e., vegetarians) and serve as something of a poor-second-cousin meat
substitute. Having run a newsletter in the past for vegetarians, it seemed
to be the case that those who were having troubles on a vegetarian diet
diet often improved when they included animal by-products such as dairy
and/or eggs, if they completely ruled out any meat (as they almost
inevitably did, of course). The potential negative long-term consequences
of doing so, however, and whether they would be worth any positives, would
be the issue here.

--Ward Nicholson <[log in to unmask]>

P.S. Mary and Sally: In your Saturday post addressing questions to your
previous post, I did not see any commentary regarding my question about
George Mann's research on atherosclerosis in the Masai (large
milk-drinkers). (Perhaps my question was overlooked due to a subject line
not tied to your original post?) Would be most interested in any knowledge
you have of later research by Mann or anyone else on the Masai. Thanks.