Human Birth Canal evolution problem?

[ryanbouma]

Hey, while searching around for what ever came to mind, I started thinking about the female curse in the garden, that Eve would be in pain during child birth. And came across this article: http://www.pnas.org/content/106/20/8151..

It's a little over my head, but I gave it a read anyways. I got to thinking... According to the article, Neanderthals had a different way of giving birth than modern humans. The article says they're unsure, but think the change may be for better heat dissipation in warmer climates where Humans originated. I see this as a bit of a problem for evolution and wondering if anyone has thoughts on the issue. Both theologically by what God did when he gave his "curse" and evolutionarily. To me, that's a fairly significant change in a short time period. Also what causes trouble for evolution IMO, is the birth canal constricted 1cm. That's going to cause more harm than good. Reproduction is a critical item to survival of the fittest. Pre-modern medicine, child birth often led to death of the mother and/or child. I would expect evolution to correct this problem rather quickly.

Thoughts?

[PerciFlage]

Reproduction is a critical item to survival of the fittest. Pre-modern medicine, child birth often led to death of the mother and/or child. I would expect evolution to correct this problem rather quickly.

Thoughts?

The two factors that combine to cause unique problems with human childbirth - big brains and bipedalism - also bring quite a lot of advantages. Our brains and stature allow us to exploit tools to an extent that no other primate can, and that's just one factor which means that human mothers tend to need to reproduce fewer times to have a chance of having at least one of their offspring reach reproductive ways. Whether the problems that humans have in childbirth are such that they need "fixing" depends on whether they are outweighed by the benefits we would lose as part of the remedy.

Also, human childbirth is less of a mortal risk than is popularly imagined. The figure of 1 death per 200 births in the days prior to forceps and sanitation comes to mind from somewhere, which obviously aren't great odds but are long enough to mean that more women than not could expect to survive even after giving birth to a sizable number of children.

[ryanbouma]

The two factors that combine to cause unique problems with human childbirth - big brains and bipedalism

I meant from Neanderthals, which according to the article, are about the same size as human babies. But ya, from primates, that's a fair point.

Also, human childbirth is less of a mortal risk than is popularly imagined. The figure of 1 death per 200 births in the days prior to forceps and sanitation comes to mind from somewhere,

That's a lot better than I would have though. I didn't think 1 in 10 or something like that. But I would have thought around 1 in 50 actually. Doctors sure make it seem like it would have been worse. I guess they need job security too

[PerciFlage]

The inflation is probably also to do with the fact that childbirth and infancy were certainly no picnic even when they were survived. Non-fatal but serious complications during labour were certainly more common, and infant mortality rates were hugely inflated. The number of women who died during childbirth - as opposed to he number of births that resulted in death - were far higher than 1 in 200 because people used to have far more children than they do today, partly due to contraception (or a lack thereof), partly due to the high likelihood of a child dying before adulthood.

[ryanbouma]

I'd still suggest it's an impedement to survival, hence evolution has a motivation to make child birth easier. Does heat dissipation trump child birth? I really don't think so. As a Day Age creationist I think possibly God made this modification in anticipation of Eve's dissobediance. Just thinking out loud here, I haven't given it much thought. And it does seem like another questionable human feature that doesn't jive with evolution, to me at least right now.

[hughfarey]

I'm not sure that the stillbirth rate was much changed by the evolution of man. In a study of cynomolgus monkeys (http://www.ncbi.nlm.nih.gov/pubmed/3892011), 22 out of 307 babies were stillborn, most of them due to presenting in a breech position. In humans the current rate is 1 in 200 (http://www.nhs.uk/conditions/Stillbirth ... ition.aspx). No doubt modern technology has improved the "natural" proportion, but it does not seem as if our peculiar gynaecological conditions made things worse rather than better.
'Survival of the fittest' has to be seen in an overall light. Any individual characteristic may or may not be 'better' than the one it evolved from. If however, it is part of a general change to overall superiority, it can be favoured over an apparently more convenient one.

[ryanbouma]

Ok suppose for a minute (and I'm not sure this is true) that modern human birthing is no "worse" than that of Neanderthals. Is it not odd that evolution would change the way women give birth without much environmental pressure.

I suppose it's unfair to ask that question, as the article already addresses it with the answer, we just don't know but possibly for heat dissipation.

Anyone else find it curious that the Bible noted this when Adam and Eve fell?

[PaulSacramento]

Genesis says that Eve's pain would multiply, which means that there already was to be pain, it would just be more so.
Since Eve wanted to KNOW what God knew, right and wrong, good and bad, PAIN and pleasure, then that is what she got.
I don't think we can look at humans and say because their "design" is not the best that there is cause to disprove evolution since evolution is about what is "good enough" for a sepcific purpose, not what is perfect.
Funny thing because, in regards to creation, it is the same situation: Man kind was created GOOD not perfect.

[ryanbouma]

Genesis says that Eve's pain would multiply, which means that there already was to be pain, it would just be more so.
Since Eve wanted to KNOW what God knew, right and wrong, good and bad, PAIN and pleasure, then that is what she got.

Do you think it's possible God planned human birth around this event? Whether TE or DA or even YEC.

I don't think we can look at humans and say because their "design" is not the best that there is cause to disprove evolution since evolution is about what is "good enough" for a sepcific purpose, not what is perfect.

That's not what I was suggesting at all. I am saying it's a problem or moderate issue. The question is out there, why did it change from Neanderthals? And why did it get mildly worse (1cm). The researchers of the article are also confused by it. Seems this works against evolution, but certainly doesn't disprove it.

From a Christian perspective, I'm wondering if it's because God knew the fall was coming. Whether TE or DA you could possibly agree God did this on purpose, to "multiply" Eve's pain.

[Neha]

How exactly is this a problem for evolution in your opinion, ryan? It can be a problem in how we understand how the lines of various homo species separated, but other than that I don't understand it, I'd like to know what you mean.

[PaulSacramento]

Genesis says that Eve's pain would multiply, which means that there already was to be pain, it would just be more so.
Since Eve wanted to KNOW what God knew, right and wrong, good and bad, PAIN and pleasure, then that is what she got.

Do you think it's possible God planned human birth around this event? Whether TE or DA or even YEC.

I don't think we can look at humans and say because their "design" is not the best that there is cause to disprove evolution since evolution is about what is "good enough" for a sepcific purpose, not what is perfect.

That's not what I was suggesting at all. I am saying it's a problem or moderate issue. The question is out there, why did it change from Neanderthals? And why did it get mildly worse (1cm). The researchers of the article are also confused by it. Seems this works against evolution, but certainly doesn't disprove it.

From a Christian perspective, I'm wondering if it's because God knew the fall was coming. Whether TE or DA you could possibly agree God did this on purpose, to "multiply" Eve's pain.

Let us look at that view:
You seem to be suggesting that God knew that Eve would fall, so He made her birth canal in such a way that child birth would be painful and even at times fatal to women and their unborn child, is that what you are suggesting?
While God certainly knew that Eve and Adam would have the possibility to fall if they chose to disobey Him, I don't think that God would decide based on that to "punish" all women and unborn children by make it more difficult than it has to be to give birth ESPECIALLY since in Genesis 1 He proclaims that humans should go forth and be fruitful and multiply.
Also, we have to address that fact that many women have virtually painless child births.
EX: My mom had a very rough birth with my older sister but would me, she didn't even think she was in labour and I was out in one push with virtually no pain at all.

And while child birth is quite painful, many a woman will tell you that an even comparable pain ( in some cases in more so) is passing a kidney stone.

I don't think we can look at the fact that childbirth is painful as something those shows that God planned it that way on purpose because He knew Eve would fall.

[ryanbouma]

Paul, interesting thoughts. I'll mull over them and try and form some kind of conclusion. I'll re-read the Biblical account and see if it ties in at all. Perhaps God made a mutation or something that constricted the birth canal in Eve's offspring and now all women. I think your mother's case would be by far the exception though. For the most part, child birth is very painful.

Neha, the problem is that the birth canal changed fairly dramatically, and became constricted by 1cm compared to Neanderthals, in a relatively short period of time. Evolution says change occurs when a mutation shows a genuine advantage, or environmental pressure selects certain traits over another. In this case, the change is significant, except there's no genuine advantage and the environmental pressure isn't really there either. One thing I think the author missed, is that the Neanderthal lived near the end/during the last ice age (correct me if I'm wrong), but humans came on the scene right at the end of the ice age. So there was environmental change, just not what I'd expect to make this kind of change. And I understand it wasn't a straight jump from Neanderthals to modern humans. But the evolutionary mechanisms aren't there for such a significant, and non-advanced, change. The author seems equally stumped

From my Day Age perspective, I see it as God giving each hominid specific features that fit His purpose and the planet's environment. See, when a designer is choosing an organism's anotomy, he can optomize it even if the environmental change is very slight. I suppose for the theistic evolutionists who think God was involved in every mutation, this would fit well in that camp as well. Because God was steering evolution in the right direction. But for the naturalist, I can't see how this works. If modern humans had a Neanderthal's birth canal, there wouldn't be any disadvantage I can understand, perhaps it would be even more conducive to reproduction.

If I'm wrong, I'm quite open to understanding the topic better. Hence why I posted the question. I'd hate to bring this up with an athiest and look like a fool when he blows my argument out of the water

[PerciFlage]

One thing I think the author missed, is that the Neanderthal lived near the end/during the last ice age (correct me if I'm wrong), but humans came on the scene right at the end of the ice age. So there was environmental change, just not what I'd expect to make this kind of change. And I understand it wasn't a straight jump from Neanderthals to modern humans. But the evolutionary mechanisms aren't there for such a significant, and non-advanced, change.

Humans didn't evolve from Neandertals, but alongside them. Anatomically modern humans (H. sapiens sapiens) and Neandertals (either H. neanderthalensis or H. sapiens neanderthalensis depending on who you ask) both emerged before the last glacial period, with Neandertals going extinct not too long before the end of that glacial period. Neandertal extinction shares a similar time frame as the rise of culturally modern humans, between 10k to 40k years ago, depending on what definition of culturally modern you use.

[PerciFlage]

If modern humans had a Neanderthal's birth canal, there wouldn't be any disadvantage I can understand, perhaps it would be even more conducive to reproduction.

One possibility is that the different size birth canals of humans and Neandertals are neutral in terms of survival rates and therefore not something that has been acted upon by natural selection. The authors conclude that childbirth was "about as difficult" for Neandertals as for humans, so pelvis structure could be more of a zero-sum drift than an adaptation.

The PNAS article you linked to didn't delve into the differences between the pelvis structures of humans, Neandertals and their most recent common ancestor. It's possible that the ancestor species had a pelvis similar to modern humans and that Neandertals changed in the larger direction whilst humans stayed the same, or that the ancestor had a Neandertal-like pelvis and humans changed in the smaller direction, or that the ancestor had a middling pelvis whilst Neandertals grew and humans shrunk.

[PaulSacramento]

Neha, the problem is that the birth canal changed fairly dramatically, and became constricted by 1cm compared to Neanderthals, in a relatively short period of time. Evolution says change occurs when a mutation shows a genuine advantage, or environmental pressure selects certain traits over another. In this case, the change is significant, except there's no genuine advantage and the environmental pressure isn't really there either. One thing I think the author missed, is that the Neanderthal lived near the end/during the last ice age (correct me if I'm wrong), but humans came on the scene right at the end of the ice age. So there was environmental change, just not what I'd expect to make this kind of change. And I understand it wasn't a straight jump from Neanderthals to modern humans. But the evolutionary mechanisms aren't there for such a significant, and non-advanced, change. The author seems equally stumped

Evolution doesn't say anything like that.
Change via random mutation can be hurtful just as it can be beneficial.
Change is random, so the change to the birth canal was just that, a random event caused by unknown factors.
That change was not beneficial.
That change was still passed on even though it wasn't beneficial and this happens within the scope of evolution.
We all have know of "hereditary" traits and problems that are passed down via the generations.
The process of "natural selection" ( which I am not 100% convinced of as being THE main factor) has still many "nuances" that we don't know about BUT what we do know is that bad mutations do passed down over the generations, just like good ones.