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I am new to this discussion group and began by reading some of the =
archived messages dating as far back as 1995. Of course nobody has =
enough time to read everything so I wonder if there is some way I can =
find out if any consensus has been reached on anything that has been =
discussed.
I got the impression that changing somebody's preconceived =
opinions/beliefs is an impossible task but it would be very informative =
to newcomers like myself if there could be some discussion of what =
consensus has been achieved in the last few years.
I am an OB/GYN practising in Canada (trained in South Africa) and is =
particularly interested in evolution as relating to the erect body =
position of humans and the effect of that on the skeleton (especially =
the pelvis) and therefore directly on the birth process. Does the erect =
position and the reasons for that in the evolutionary sense (ability to =
run faster for instance) lead to the necessity of a smaller, narrower =
pelvis?
In the reproductive sense there is a direct competition between the =
mother, who will be better off if the baby is small, and the fetus, who =
will be better off if born big (without damage of course). The =
mechanical problems of delivering a big baby without excessive damage to =
mother and baby and the interplay of this competition, is fascinating. =
There are some indications that pregnant woman can regulate the size of =
the baby, possibly by restricting the nutrients delivered by the =
uterine/placental perfusion. Thus smaller women will have smaller =
babies etc. This holds even when a donor embrio of large parents is =
implanted into a smaller woman. The same has been noted in animals.
Could this be the reason that human babies are so totally undeveloped in =
comparison to some of the other primate species for instance the large =
apes? Longer gestation to provide further development would of =
necessity lead to larger size and thus an impossible mechanical birth =
problem.
Could anyone tell me if other primates have developed the rotational =
birth process without which almost no human birth is possible? Could =
this have been a development in response to the increasing problems from =
increased brainsize and decreasing pelvic size?
Our increasing use of cesarean section for obstructive labour has =
removed nature's way of preventing genes coding for insufficient =
pelvices to be transmitted. The flip side could be that it has also =
removed the previous hindrance to a possible increase in brainsize in =
the human fetus.
I wonder if anyone has information on the pelvic size of Neanderthals, =
who apparently sometimes had bigger or at least equal brain sizes than =
modern humans?
It is my belief that in due time, cesarean birth will become the rule =
rather than the exception. As it is, most human births come at high =
cost to the mother as a result of mechanical problems as mentioned =
above. The prevalence of genital prolapse and incontinence problems in =
parous women is unbelievably high and I truly believe this is one of the =
silent epidemics of our time.
Any coments?
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