Someon asked: How is it that new people will not be born by eating paleo? jean claude said: ...there is a regulation of births and populations in wild animals and also in Huntergatherers.....This phenomenon is yet to receive plausible explanations...Malinowski studying the trobriand islands have noted the inability of teen agers to get pregnant despite a very rich sexe life....only the married women were getting pregnant. My response: I think a very natural explanation for this lies in the fact that in more primitive cultures, girls are generally leaner and reach menarche at much later ages, often at the age of 17 or 18. If a girl menstrates later, but has sex at an early age, she is not going to get pregnant. In many of those cultures, the girls don't marry until after they begin to menstrate, hence the correlation with marriage and pregnancy. Also, later age of menarche would mean delayed fertility, as some might not get pregnant until after two or three years of menstrating. Modern industrialized diets stimulate overly high estrogen levels. Why is this? It has been observed that Eskimos reach menarch at younger ages when they switch to modern diets. Some have explained this as being a result of high sugar and vegetabel oil consumption, which lead to higher body fat and estrogen levels at younger ages, which stimulate earlier onset of menarche and fertility. If women are leaner, they will generally menstrate later, and thus delay fertility. Females eating Westernized diets are now menstrating at earlier and earlier ages. This can be attributed to higher estrogen levels in the body, due to high carb, high vegetable oil diets, excess body fat, as well as xenoestrogens in drinking water, and from foods stored and heated in plastic, and estrogenic hormones in commercial, conventional animal foods. Btw: we can see that some girls are obviously chubby or obese at a young age; others may thin (i.e., not overtly fat) or average looking, but overfat (i.e., they have very little lean mass and high overall percentage of body fat), which can lead to high estrogen levels none the less. My 2 cents worth. Rachel