At 01:06 2001-01-01 -0800, Kevin wrote:

>In the wild, Sow Bears will have miscarriages if there is not enough food. I
>wonder if there is a connection between human miscarriages and not eating a
>biologically correct diet.

A pregnancy followed by care and breast feeding is a big "cost" for the
mother. As the foetus has only half of its genes in common with her,
there is a struggle between them. The foetus interest is to be born and
fed. Genetically the placenta belongs to the foetus also, and it tries
to get as much as possible out of the mother, with help of hormones sent
into her bloodstream. The mothers interest is to have the best offspring
possible. If she has not enough, or wrong, food, it is better to end this
pregnancy as soon as possible, and try another one as soon as possible
when circumstances might be better (or the chance that the next foetus is
less demanding (boys are usually worse here). So she tries to have a
miscarriage, and might succeed.
Toxin (from for example food) control is handled by a part of the brain
stem called CTZ. This is one of few areas of the brain where blood can
pass, and there the blood is sampled for toxins, with nausea as one result.
Probably the pregnancy-protecting hormones from the foetus make more
blood pass to the CTZ resulting in higher toxin sensitivity.
(Learned from: "Evolutionary Psychology" by Christoffer Badcock.)

- Hans