>Rickets seems to be on the rise in breast-fed dark-pigmented infants, =
>who are *pre-disposed* to rickets (pigment blocks the rays that are =
>required by the skin to manufacture the Vit D).

I'm uneasy with the way this is phrased.  Dark-pigmented infants are NOT
pre-disposed to rickets.  That implies some sort of genetic underpinning to
developing rickets.  Dark skin is adaptive in areas with high UV radiation,
and in most of the world where really dark-skinned people live (Africa near
the Equator, southern India, Australian Aborigines), people are outside
most of every day and most wear relatively few clothes.

In the North Carolina cases, it is the specific combination of
dark-pigmented skin and CULTURAL rules/habits against sun exposure that
lead to rickets.

You mostly find rickets today in northern countries/latitudes with
immigrant populations that don't go outside, or are completely covered when
outside.


----------------------------------------------------------------------------
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Katherine A. Dettwyler, Ph.D.                         email:
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Anthropology Department                               phone: (409) 845-5256
Texas A&M University                                    fax: (409) 845-4070
College Station, TX  77843-4352
http://www.prairienet.org/laleche/dettwyler.html

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