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

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

One theory that tries to explain the increased evolutionary fitness =of Homo=20sapiens is the development of speech, that made communication and thus =the=20development of culture possible. The development of speech led to a =massive=20increase in certain parts of the brain, particularly the frontal and =temporal=20lobes, 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=20since the fetus survives best if it is large, but with obvious =consequences for=20the mother. The birthing process can be likened to a competitive =interaction=20between the mother and her fetus, with some common ideals (for instance =the=20survival of both), but also some divergent goals; to personally come =from the=20experience in as good a shape as possible.

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

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

Evolutionary theory has some further solutions for the problem of=20"reproductively unfit" individuals as a result of too small =pelvises,=20since mothers with pelvises too small to give birth would die during =childbirth=20and thus not propagate their (and their partner’s) genes (the baby =would=20almost always die as well). The other side of the coin is that the =inability of=20babies 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=20which is where Orthodox religious views come in. Evolutionary theory is =just=20that – a theory trying to explain what is seen in nature and known =from=20science. This theory has not however been proven and a ="Creationist"=20view of the origin of life is just as valid. My own personal view is a=20combination of "creation through (some aspects of) evolution". =Whatever view one holds however, one cannot escape the fact that the =delivery of=20a healthy infant without significant damage to the mother, is a high =stakes=20competitive situation where things can (and do) go wrong.

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

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

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