About seven years ago I swear I read a research journal article that basically discussed how mixed aborigine/caucasian pregnancies had far, far higher odds of miscarriage than unmixed pregnancy or mixed pregnancy of other ethnic groups. If that wasn't a hallucination on my part, then that would suggest a reduced genetic compatibility and has some intriguing implications with regard to human evolution. Of course that would be a horribly un-PC finding, but it intrigues me nonetheless.
Unfortunately, that was unrelated to my research at the time (which was aboriginal sex partner selection) and when I did become interested several years afterward I couldn't remember where to find it again. I'd have to retrace the steps of my research back then to see if I stumble across it.
Boy--is that EVER un-PC! Here's all I could find:
Mankind. 1981 Jun;13(1):37-55. Related Articles, Links
The determinants of fertility among Australian Aborigines.
Cowlishaw G.
PIP: This paper concerns the determinants of fertility of precontact Australian Aborigine women. Emphasis is placed on social organization as well as the physical environment and considerations of adaptation. The key to understanding the fertility of Australian Aborigines is the structural tension evident in male-female relations. Ethnographic data on hunter-gatherers fertility indicate a low fertility rate, e.g. 4.7-5.2 live births/woman for the Kung. Traditional Aboriginal physiological fertility was also low if infant mortality is separated from infertility. Past studies of population and transition theory in pre-contact situations have attributed increase in population to reduction in mortality. This paper suggests that there must have been an increase in the birth rate. Factors affecting ovulation, conception, and parturition are examined for traditional Aboriginal populations. Ovulation is affected by nutrition, lactation, and introcision. Lack of body fat in women causes anovulation due to insufficent energy reserves. Increased fertility appears to be a greatly reduced energy expenditure and an increased carbohydrate intake leading to a build up of body weight. Pre-contact Aboriginal fertility was low because of a low caloric intake and a high energy expenditure. Prolonged lactation does not seem to cause birth spacing. The actual length of time after parturition appears to be an independent cause of reduced prolactin, and of reestablishment of ovulation. Stress and anxiety are factors which could reduce fertility by causing anovulation in women and/or reduced sperm counts in men. Contraception is affected by coital frequency and male fertility. Aboriginal coital frequency may have been affected by the lack of privacy and competition of a co-wife. Gestation is affected by spontaneous abortion, sterility, and foetal wastage. Harsh conditions of traditional Aborigines may have affected their ability to conceive. Voluntary controls on fertility for Aborigines include rituals, avoidance of coitus, taking medicines, abortion, and infanticide. Low fertility of precontact aborigines is accounted for by diet and energy expenditure, with limited coital frequency and foetal wastage as probable contributing factors. Fallopian tube blockage could account for the high rate of infertility of women. Social organization, values, and beliefs are important to take into account.
That reminds me, somewhere I read the theory that Neandertals couldn't give birth to Cro-Magnon babies because the babies' heads were too big and the N mothers' hips weren't built for the passage of big heads. The babies would have died, and/or the mothers; thus no evidence of interbreeding.
Now, that's probably been refuted---their hips aren't so narrow and babies' heads are soft for good reason (so to speak).
But just in case, there it is.
By the way, regardless of how the Neandertals met their waterloo, you have to wonder what would have been the shortcomings of a half-Cro-Magnon child among their kind. What was his (or her) fitness for Neandertal life? Did he seem so frail and sorry a creature, they'd have just pitched him?
The early question on this thread stands---why, how, did they ALL vanish? I'm baffled.