Evolution - February 1999: Human birth

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I recently posted my first posting to the site with some info about =
myself - so far without response. Anyway, I am in the process of =
writing a book on the human pelvic floor and how that relates to the =
birth process. Naturally, the erect position of humans and the effect =
of that on the pelvis and birth would come into it.
I now want to take the liberty to attach a few paragraphs dealing with =
this issue and to request a critique from a factual point of view. Any =
suggestions will be welcome.

The earliest fossil records of a hominid bipedal (human-like and walking =
upright), can be dated to about 3.5 million years ago. These species, =
called Australopithecines, had an almost human-shaped pelvis, but had a =
much smaller brain capacity. There are numerous theories trying to =
explain the evolutionary benefit of an erect posture that ultimately led =
to hominid species becoming the dominant species on the planet. To me =
the most logical theory is that the freeing of the hands for purposeful =
manipulation of tools provided an increased ability to defend itself and =
to acquire food. These factors could have led to an increased =
evolutionary fitness in terms of competition with other species.

Various evolutionary processes, and especially the development of =
speech, theoretically led to a massive increase in brain capacity. This =
increase in brain capacity is well documented in the fossil records with =
a direct line that can be drawn from Australopithecus, through Homo =
habilis and Homo erectus and Homo sapiens. It is currently believed that =
Homo sapiens and another species called Homo Neanderthalensis actually =
coexisted for a long period of time and until as recently as 30,000 =
years ago. It is believed that the two species did not interbreed and =
that Neanderthalensis might have become extinct as a result of direct =
competition with Homo sapiens.

One theory that tries to explain the increased evolutionary fitness of =
Homo sapiens is the development of speech, that made communication and =
thus the development of culture possible. The development of speech led =
to a massive increase in certain parts of the brain, particularly the =
frontal and temporal lobes, with the end result a brain that is often =
over 2000 cc in size.

The large brain size obviously creates problems for the birthing process =
since the fetus survives best if it is large, but with obvious =
consequences for the mother. The birthing process can be likened to a =
competitive interaction between the mother and her fetus, with some =
common ideals (for instance the survival of both), but also some =
divergent goals; to personally come from the experience in as good a =
shape as possible.

Recent evidence from scientific studies has indicated the possibility =
that the pregnant mother can directly influence the size of her unborn =
fetus, especially towards the end of her pregnancy. It has apparently =
been shown that this observation holds true even in the setting of donor =
embryos from large genetic parents into smaller surrogate mothers, with =
resultant smaller infants that would have been suspected. The =
theoretical way the birth mother can accomplish this is by restricting =
the bloodflow to her uterus and thus the availability of nutrients to =
the fetus.

This finding may be evidence of an attempt of the mother to protect her =
own interests to the general detriment of the fetus. Of course it should =
be self-evident that if there were an insurmountable discrepancy between =
the pelvis of the mother and the size of the fetus, it would also be to =
the clear disadvantage of the infant.

Evolutionary theory has some further solutions for the problem of =
"reproductively unfit" individuals as a result of too small pelvises, =
since mothers with pelvises too small to give birth would die during =
childbirth and thus not propagate their (and their partner=92s) genes =
(the baby would almost always die as well). The other side of the coin =
is that the inability of babies with increasing brain size to be born =
alive, was theoretically an inhibiting factor in further evolutionary =
brain size development.

These theories raise as many questions as answers of course, not least =
of which is where Orthodox religious views come in. Evolutionary theory =
is just that =96 a theory trying to explain what is seen in nature and =
known from science. This theory has not however been proven and a =
"Creationist" view of the origin of life is just as valid. My own =
personal view is a combination of "creation through (some aspects of) =
evolution". Whatever view one holds however, one cannot escape the fact =
that the delivery of a healthy infant without significant damage to the =
mother, is a high stakes competitive situation where things can (and do) =
go wrong.

Our ability to deliver babies safely by cesarean section in cases of =
obstructed labor has revolutionized our ability to intervene in nature =
(whether that should be read "evolutionary" or "Divinely" created). This =
ability has not only removed the necessity for an adequate pelvis, but =
also the impediment to possible evolutionary brain-size development.

The upright posture of humans brings with it a number of other problems =
as well. When we look around the animal kingdom, we find in most mammals =
that the pelvic " floor" is not a floor at all, but a wall. Since the =
usual primate posture is for the body to be horizontal, the brunt of the =
intra-abdominal weight does not fall on this structure at all, but =
rather onto the anterior abdominal wall. In the human the pelvic floor =
became the most important support structure for pelvic and abdominal =
contents. The full force of gravity has to be counteracted by the pelvic =
floor and with weak pelvic floor muscles, the fascial layers (to be =
discussed later in detail) are the last defense against prolapse.

In the global scheme of things, the integrity of pelvic floor over time =
is after all not all that important. Nature couldn't care less if your =
bottom fell out at age 50. The most important biological functions =
ensuring the survival of our species (reproduction) have long been =
completed at this age. During most of human existence people furthermore =
rarely made it to this age. Fortunately this has changed in a big way. =
It becomes imperative to us to look with new eyes at this problem and to =
develop new strategies to protect those parts of our bodies less likely =
to stand the test of time and aging.

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The pelvic floor is an evolutionary newcomer:

The earliest fossil records of a hominid bipedal (human-like and = walking=20 upright), can be dated to about 3.5 million years ago. These species, = called=20 Australopithecines, had an almost human-shaped pelvis, but had a much = smaller=20 brain capacity. There are numerous theories trying to explain the = evolutionary=20 benefit of an erect posture that ultimately led to hominid species = becoming the=20 dominant species on the planet. To me the most logical theory is that = the=20 freeing of the hands for purposeful manipulation of tools provided an = increased=20 ability to defend itself and to acquire food. These factors could have = led to an=20 increased evolutionary fitness in terms of competition with other = species.

Various evolutionary processes, and especially the development of = speech,=20 theoretically led to a massive increase in brain capacity. This increase = in=20 brain capacity is well documented in the fossil records with a direct = line that=20 can be drawn from Australopithecus, through Homo habilis and Homo = erectus and=20 Homo sapiens. It is currently believed that Homo sapiens and another = species=20 called Homo Neanderthalensis actually coexisted for a long period of = time and=20 until as recently as 30,000 years ago. It is believed that the two = species did=20 not interbreed and that Neanderthalensis might have become extinct as a = result=20 of direct competition with Homo sapiens.

One theory that tries to explain the increased evolutionary fitness = of Homo=20 sapiens is the development of speech, that made communication and thus = the=20 development of culture possible. The development of speech led to a = massive=20 increase in certain parts of the brain, particularly the frontal and = temporal=20 lobes, with the end result a brain that is often over 2000 cc in = size.

The large brain size obviously creates problems for the birthing = process=20 since the fetus survives best if it is large, but with obvious = consequences for=20 the mother. The birthing process can be likened to a competitive = interaction=20 between the mother and her fetus, with some common ideals (for instance = the=20 survival of both), but also some divergent goals; to personally come = from the=20 experience in as good a shape as possible.

Recent evidence from scientific studies has indicated the possibility = that=20 the pregnant mother can directly influence the size of her unborn fetus, = especially towards the end of her pregnancy. It has apparently been = shown that=20 this observation holds true even in the setting of donor embryos from = large=20 genetic parents into smaller surrogate mothers, with resultant smaller = infants=20 that would have been suspected. The theoretical way the birth mother can = accomplish this is by restricting the bloodflow to her uterus and thus = the=20 availability of nutrients to the fetus.

This finding may be evidence of an attempt of the mother to protect = her own=20 interests to the general detriment of the fetus. Of course it should be=20 self-evident that if there were an insurmountable discrepancy between = the pelvis=20 of the mother and the size of the fetus, it would also be to the clear=20 disadvantage of the infant.

Evolutionary theory has some further solutions for the problem of=20 "reproductively unfit" individuals as a result of too small = pelvises,=20 since mothers with pelvises too small to give birth would die during = childbirth=20 and thus not propagate their (and their partner’s) genes (the baby = would=20 almost always die as well). The other side of the coin is that the = inability of=20 babies with increasing brain size to be born alive, was theoretically an = inhibiting factor in further evolutionary brain size development.

These theories raise as many questions as answers of course, not = least of=20 which is where Orthodox religious views come in. Evolutionary theory is = just=20 that – a theory trying to explain what is seen in nature and known = from=20 science. This theory has not however been proven and a = "Creationist"=20 view of the origin of life is just as valid. My own personal view is a=20 combination of "creation through (some aspects of) evolution". = Whatever view one holds however, one cannot escape the fact that the = delivery of=20 a healthy infant without significant damage to the mother, is a high = stakes=20 competitive situation where things can (and do) go wrong.

Our ability to deliver babies safely by cesarean section in cases of=20 obstructed labor has revolutionized our ability to intervene in nature = (whether=20 that should be read "evolutionary" or "Divinely" = created).=20 This ability has not only removed the necessity for an adequate pelvis, = but also=20 the impediment to possible evolutionary brain-size development.

The upright posture of humans brings with it a number of other = problems as=20 well. When we look around the animal kingdom, we find in most mammals = that the=20 pelvic " floor" is not a floor at all, but a wall. Since the = usual=20 primate posture is for the body to be horizontal, the brunt of the=20 intra-abdominal weight does not fall on this structure at all, but = rather onto=20 the anterior abdominal wall. In the human the pelvic floor became the = most=20 important support structure for pelvic and abdominal contents. The full = force of=20 gravity has to be counteracted by the pelvic floor and with weak pelvic = floor=20 muscles, the fascial layers (to be discussed later in detail) are the = last=20 defense against prolapse.

In the global scheme of things, the integrity of pelvic floor over = time is=20 after all not all that important. Nature couldn't care less if your = bottom fell=20 out at age 50. The most important biological functions ensuring the = survival of=20 our species (reproduction) have long been completed at this age. During = most of=20 human existence people furthermore rarely made it to this age. = Fortunately this=20 has changed in a big way. It becomes imperative to us to look with new = eyes at=20 this problem and to develop new strategies to protect those parts of our = bodies=20 less likely to stand the test of time and=20 aging.