C-sections effecting our evolution - Page 2

[applejuice]

Amyjeans, I asked my own mom that very question 40 years ago. I asked if something catastrophic happened as a famine or something to disrupt our civilization, would women or women's bodies forget how to give birth since it had not been imprinted for generations.

I mean, if a woman suddenly in such a situation was pregnant and went into labor who would help her, how would she know what to do or how to manage. I know much of birth and nursing is innate, but women have always had midwives to help them. Since surgerical birth removes any cognitive responsibilities from the mother for the outcome and care of her baby, how can she know what to do?

I had a neighbor who had one child seven years before I had my first child. She told me she asked her mother what to expect from labor and delivery and her mother told her she did not know since she had been knocked out in the 1930s and 1940s for the births of her children.

Natural Birth may become an anomaly eventually.

I did have an anthropology professor who believed that the necessity for more surgical births was because our brains and therefore our heads, are getting bigger. I do not know. Maybe just our skulls are getting thicker.

[liseux]

"Since surgical birth removes any cognitive responsibilities from the mother for the outcome and care of her baby, how can she know what to do?" Applejuice

Applejuice, I`m just wondering what do you meant by this, just that a c/s is kind of alien to the natural order or that a mom doesn`t have instincts even after the surgery?

[liseux]

If anything, maybe c/s mess with evolution b/c they keep alive some of the moms who might have died during labor in the past, due to some of the severe and rare anomalies that prevent vaginal birth. Yet, now these mamas can have a baby surgically so some women keep giving birth to daughters with possibly similar issues where the line might have ended with them.

Like all things in nature, evolution is not perfect and clean, there will always be weird things popping up that don`t fit with where we thought humans were going.

[~member~]

Originally Posted by newbad

I know that studies show that it generally takes longer for a woman's milk to come in when she has had a c-sect.

I think I read that same study, but they found it was the fault of the drugs given, not the fact of the mother being cut open. Once the placenta leaves the wall, the proper hormones still kick in.
It's the anesthesia and narcotics that are affecting mom's milk, not the actual act of cesarean.

[~member~]

Originally Posted by amyjeans

It frightens me that not only will most children who are born via c-section do not experience the journey of vaginal birth, but could potentially never inherit the coding needed to perform a vaginal delivery. Does that make any sense?

In a way, yes. I have had this same discussion in the past. I think it falls more along the lines of having a mother who is more willing to say "YES!" to her daughter choosing a cesarean, kwim?

I don't believe for a second that the "Birth code" that was formed millions of years ago, could be erased that quickly.

[~member~]

Originally Posted by applejuice

I know much of birth and nursing is innate, but women have always had midwives to help them.

That is not true, as many tribal women still have unassisted births, as they have done forever.
Midwives were only called when there was trouble.

[wombatclay]

Speaking as an anthropologist and echoing some of the points made previously....

An early school of evolutionary thought (the now abandoned theories of Lamarckian evolution) suggested that evolution might act through "acquired" traits. It's an interesting set of theories, and very similar in to the concern raised by the op, but if you pull the concept out a little you can see where it falls short. Like the posters who've mentioned circumcision, Lamarkian evolution would suppose that a circumcised person would pass on that trait, and all his descendents would be circumcised (or the classic example of a person who's arm is cut off having children with only one arm). Now you could argue that a circumcised individual might create a cultural environment in which descendents would be circumcised, but it has nothing to do with biology.

Our current understanding of evolution suggests that evolution acts through reproductive success and generally selects "against" rather than "for" a trait. So if a person has something "extra" which doesn't get in the way of their reproductive success (say an appendix, or tonsils), they can pass it along to their offspring and evolution "doesn't care". It's only when an individual has something which impedes their reproductive success that that trait/characteristic is removed from the gene pool over time due to the simple fact that the carrier of the trait can't reproduce.

So a surgical procedure performed on a woman should not have any impact on her descendants and evolution (as such), except to the extent that a previous poster mentioned...women and infants who might otherwise have died (and been removed from the genetic stock) may now live and reproduce. So very gradually we might find an increase in infant head size (we are talking hundreds of thousands of years here at the soonest).

Of much greater impact (in terms of evolution) is modern medicine and our ability to prolong the lives of people who might otherwise have died before reaching reproductive age, as well as medical advances in assisted fertility. It's a complex and really fascinating topic!

[applejuice]

Originally Posted by MamaInTheBoonies

That is not true, as many tribal women still have unassisted births, as they have done forever.
Midwives were only called when there was trouble.

They did not have a trusted female companion help them?

I only say this since even throughout the mammal kingdom, females help each other in labor. This is even seen in humpback whales, and most other mammals.

Just asking, not wanting to debate. I do know that throughout the mammal kingdom, most females quietly labor alone in a place that the mother feels safest.

We could learn a thing or two (or three or four) from them.

[~member~]

Okay, along those lines, I would say IVF would be a more likely possiblity, ie-the sperm's "natural" environemnet has changed, therefore the male sperm might change and no longer be "good" at natural impregnation....maybe the sperm now have evolved to "need" saline solution or whatever chemicals they use in the lab, kwim?

And, perhaps the female's eggs/ovums might change to be "better" at waiting to attach to the uterine wall, so then we may see more multiple births?

I guess, we are going to see change, but we really can't "know" what will happen until it does, right?

[applejuice]

Originally Posted by liseux

Yet, now these mamas can have a baby surgically so some women keep giving birth to daughters with possibly similar issues where the line might have ended with them.

A nurse told my Father this in the early 1950s. She was talking about other disorders by which most people would die earlier and exit the gene pool before reproducing.

Applejuice, I`m just wondering what do you meant by this, just that a c/s is kind of alien to the natural order or that a mom doesn`t have instincts even after the surgery?

Just that there may be an "imprinting" of information from mother to child in the process of birthing through the birth canal...it is known that there is a hormonal connection between the pituitary gland and the placenta for the commencement of the labor process, and a chemical preparation in the baby's nervous system by the production of adrenal-like stress hormones produced by the central nervous system known as cathecholamines which prepare the baby to take its first breath and for life outside the womb. Too much of these stress hormones can cause fetal distress and meconium staining, and too few can cause fetal apnea and lethargy which are too often present with a baby born too early without any labor through the surgical process.

Does that make sense?

Let me be fair; there are plenty of healthy term babies born surgically and plenty of babies who are born with problems through the birth canal. Just doing some generalized explaining here.

[~member~]

Originally Posted by applejuice

They did not have a trusted female companion help them?

No. Only if needed. My grandmother gave birth to all five of her children alone. Her mother did the same and did her mother. They said they would use their ricing stick and squat, using the one free hand to catch their baby.
My mother also gave birth unassisted, except with me. The doctors tied her down and pulled me out with forceps.
My parents were visiting a small city, when my mom thought she might be in labor and my dumb father forced her to go to the hospital. In hindsight, my mom was most likely just having Braxton Hicks and not true labor. They had lost their first son, so there was the added fear of losing me, too.

Also, I thought I remember reading about a tribe in New Guinea whose women give birth unassisted, also.

I do know that many women do need the support, I did. I know my birth experiences were traumatic when I had no one there to actively support and advocate for me. But I do wonder if my births would not have had any trauma if I had just done it on my own.
My sisters have had unassisted births. My cousins, also.
Maybe that could go towards "proof" of "coding".
My 9 yr old dd has already said that if she wants to be a mother someday, she's gonna have her baby at home.

I guess, I am really just saying that if for some reason a mother found herself alone without support, her body will do the work for her.

[~member~]

I just wanted to add, that the women in my family were not out of range for getting help, should she need or want it. I reread my post and it sounds like they are in the middle of nowhere.

As far as I know, my grandmother was the only woman who was forced to work and keep working through her births. She gave birth twice(?) in the potato fields. Quite similar to mothers in Third World countries who cannot afford to quit, so give birth, put baby in the sling and keep working.

[applejuice]

Originally Posted by MamaInTheBoonies

I guess, I am really just saying that if for some reason a mother found herself alone without support, her body will do the work for her.

As it should; I am hoping that will never change.

That is why I am :ing on this thread heavily.

Thank you.

[applejuice]

Originally Posted by MamaInTheBoonies

Quite similar to mothers in Third World countries who cannot afford to quit, so give birth, put baby in the sling and keep working.

As hard as that may sound, those are the models I held myself up to when I was pregnant and when I was in labor. It helped each of the four times...but I live in this society, so I am sure that contributed to the PPD i felt the first three times. The last time, I got smart, rested and kept my DH close. It helped. I guess I am in between the first and third world as a mother.

[wombatclay]

IVF is a good example...but again, IVF wont change the nature of the sperm itself (at least not from an evolutionary point of view).

It's sort of hard to explain in writing...but...apologies in advance for the long post!

Without IVF, a man who's sperm has a motility problem (or whatever the problem happens to be, let's just use motility) wont pass along this trait since he simply wont be able to father children (sons in particular) who might share his condition. Evolution has worked by removing this person (and his slow sperm) from the picture.

With IVF, the motility of the sperm is no longer an issue and this man can father sons who may also have problems with their own sperm motility. If these sons have adequate financial resources (and an interest in biological reproduction) they too can pass along a tendancy to sperm motility problems in their own offspring. If, on the other hand, they lack the financial means or simply never reproduce, then evolution has "won" again and the slow sperm trait is once more removed from the picture.

Here's where it gets a touch convoluted....

The point here is that the continuation of the slow sperm trait requires a cultural/medical intervention at each stage. If at any point the original man or his male offspring suffer from slow sperm and DON'T turn to a medical solution, the "problem" corrects itself and evolution drops them out of the picture.

If they DO turn to a medical solution to allow them to reproduce, they still aren't having a significant impact evolutionarily since their decision to enhance their own sperm motility does not change the fact that the majority of reproductive males have adequate sperm. And since evolution selects /against/ traits, males with adequate sperm will continue to reproduce, passing along happy healthy sperm to their male offspring.

Medical technology can increase the chances that there will be more males "out there" with slow sperm, but until such a time as ALL of these "slow sperm" males are guaranteed the medical assistance necessary to reproduce (and they all choose to reproduce, and all of their offspring carry the slow sperm trait) there wont be a significant shift in the ratio of slow sperm males to adequate sperm males.

Now, if there was a sudden ADVANTAGE to having slow sperm....then evolution would really kick in as the till-then adequate sperm males suddenly found themselves unable to reproduce (with evolution selecting against them). But there would have to be a reproductive advantage to having that sperm motility problem before you'd see anything close to a significant shift in the sperm population. And again, even when we're talking about evolution "kicking in" and moving fast, we're still talking hundreds of human generations at best, and more likely thousands of human generations.

Which is kind of reassuring if you think about it....there's really very little we can do technologically to completely mess ourselves up over the long run!

Congrats if you made it through the mini-lecture, and I apologize again for such a long post...not only am I an anthropologist, I'm also a reference librarian and a assistant professor, so I tend to ramble on and on!

[~member~]

Originally Posted by wombatclay

With IVF, the motility of the sperm is no longer an issue and this man can father sons who may also have problems with their own sperm motility. If these sons have adequate financial resources (and an interest in biological reproduction) they too can pass along a tendancy to sperm motility problems in their own offspring.

But we might see that happening in the near future, as IVF has risen. Which kind of brings us back to the cesarean question, with the rise in c-sec do we see mothers who cannot birth vaginally, right, and whose daughters, then also cannot birth vaginally?

ETA: their brains would be missing the codes to signal the hormones to produce to start natural labor, or maybe the brain stops producing the needed chemicals for the cervix to open, so then we have mothers with "cervical failure"(?).

[forshure]

So, I have a couple degrees in anthro...and I also just love replying to interesting threads on MDC.



First of all, natural selection operates on the level on the individual and on his/her ability to reproduce successfully. So, to use the dentist's example, a woman might, through some random mutation, end up having teeth and a jaw just a bit more suited for her diet. Those teeth would give her a slight advantage so that she would survive to her childbearing years and have a bunch of children. Some of those children will have her nifty dental features and some would not. The children who did would be at a slight advantage and, over millions and millions of years, everyone in the population might come to possess those features if they were a true advantage to reproduction.

Not just an advantage to eating but to reproducing...

On the other hand, she could end up with a variation that isn't naturally selected for, like, slightly pointier canines. Let's say, she lives in a vegetarian society so there's no natural selection pressure to rip into meat. They don't hurt but they don't help. But, for some reason, males really dig those pointy chompers so they are sexually selected for. (If everyone thought that having pointy canines made you unworthy to be a mother, they would be selected against even if they were neutral in terms of natural selection.)

So, I disagree with the dentist's POV. The jaw has become progressively smaller over time, leaving less room for wisdom teeth. And, yes, that is in response to our changing diet as well as to other changes in the shape of our skulls---big old neocortex, voice box shaped for speech, sexual selection for chins, who knows? Let's say, for the sake of argument, that natural selection has selected for those who don't produce wisdom teeth since that gives them a slight advantage somehow. They're slightly heartier because they don't have to invest in those totally unnecessary teeth, they don't have a risk of impacted/infected teeth, they mate more because they have better breath, etc.

So one view might be that surgical removal of wisdom teeth is actually interfering with the process of natural selection, since it's allowing people with the genetics to produce wisdom teeth to masquerade as non-wisdom toothed individuals with all of those same advantages. In the same way, let's say women favored men with smaller foreskins---not saying this is true, ladies---but, if it were, and if sexual selection had its way, the foreskin would get smaller and smaller over time. Or, heck, let's say women favored foreskins that were a little darker or shaped in a cetain way or whatever. It doesn't matter. What matters is that surgically removing the foreskin disguises the natural variations in foreskin size (and shape and color) so that sexual selection can no longer operate on that feature.

What that means is that kids will continue to be born with or without wisdom teeth, but, in the US, among those with dental care, that factor will not be worked on by natural selection.

Okay, so now to surgical birth. As everyone in this forum already knows, human babies are born very very prematurely compared to other primate species. The reason is that human babies have big brains and women need to be able to walk. The pelvis is the limiting factor. It's as big as it's gonna get down there. So, over millions of years, natural selection has operated on the baby---favoring those cranial plates that can mold during vaginal birth, favoring babies that were born earlier so more brain development could happen during the "fourth trimester," etc.

Back in the day, when there was a true "mismatch" between pelvic size and baby's skull, women would die and so would their babies. If the baby was born too early, the infant wouldn't survive. So there was INTENSE pressure for the pelvis and the baby's head to be in perfect balance, size-wise, and for the baby to be born just mature enough to be able to make it in the outside world. Women today are the result of this intense pressure since, if our ancestors weren't able to birth vaginally, and babies weren't born at the right time, we wouldn't be here. Even c/s babies didn't typically survive long unless there was a wet nurse available...and the moms never survived.

So, the increase in surgical births, is removing this intense pressure on pelvic size and baby head size since women with smaller pelvises and babies with bigger heads can survive. Again, these are rare circumstances---probably less than 5%---since we are the result of millions and millions of years of pressure to keep head and pelvis in sync. But, since surgical birth has only been truly possible for a few decades, I don't think it will have any effect on evolution or the ability of children born by c/s to give birth vaginally. And, again, those kids would have to be selected for so that small pelvises or big heads would become an advantage rather than a neutral feature.

BTW: I think it's a good thing that we have technological advances that allow infants and mother who would have died to survive. I'm glad that we can supplement with formula for the 5% of moms with low supply. I'm glad that we can perform c/s for the 10% of women with medical conditions that make vaginal birth an impossibility. But I think when you have c/s rates---especially elective c/s---and formula feeding rates as high as they are in the US, then something is tremendously out of balance.

Can you tell that my DS is napping so I had time to type this?



wombatclay: I enjoyed reading your post, and I'm glad that there are other long-winded anthro folks on MDC!

[~member~]

Originally Posted by forshure

So, I have a couple degrees in anthro...and I also just love replying to interesting threads on MDC.

But none of those deal with chemical changes that are purposefully given, as what researchers study and do.

Is there a study showing what happens to mice who are repeatedly birthed by c-sesarean? Do their fifth or eight generation daughters give birth vaginally?

[wombatclay]

their brains would be missing the codes to signal the hormones to produce to start natural labor, or maybe the brain stops producing the needed chemicals for the cervix to open

Forshure says it really well...(much better than I did!)

since surgical birth has only been truly possible for a few decades, I don't think it will have any effect on evolution or the ability of children born by c/s to give birth vaginally. And, again, those kids would have to be selected for so that small pelvises or big heads would become an advantage rather than a neutral feature.

Just like the cultural trend to anesthetize a laboring woman didn't prevent her female children from being able to labor while "awake", a girl born via c/s shouldn't have a problem delivering vaginally. Evolution is slllloooooooooow.

[~member~]

Originally Posted by wombatclay

Just like the cultural trend to anesthetize a laboring woman didn't prevent her female children from being able to labor while "awake", a girl born via c/s shouldn't have a problem delivering vaginally. Evolution is slllloooooooooow.

I thought it was proven not to be that slow. Six generations for one species, eight for another, but certainly not thousands. And these were natural, no chemicals introduced, no surgerical processes, nothing like that.

Obviously, scientists know that you can interject variables that create change within one generation.

Just something to think about, kwim?