I don’t mean physically…
Since continuing the species is so important, why hasn’t evolution made it easier for a woman to give birth?
I believe the current thinking is that difficult childbirth is the result of the human brain having evolved so quickly. (Big brain = large head = difficult birth) In another 10,000 years or so womens’ hips will be large enough to handle the job with ease, unless the fashion magazines win out.
This infro is from a supplemental booklet provided with the PC strategy game Evolution
Plus, I doubt that the pain of childbirth has a significant effect on the desire of humans to procreate.
Cosby said it best:
“Take your lower lip in your hand… …Now pull it completely over your head…”
Exactly, add in low infant mortality rate and evolution has done its job.
I disagree the the females hips would evolve to become wider for two reasons
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Gravity works against the mother, especially during the third trimester. There would be a higher incidence of premature birth and a higher mortality rate due to the higher probability of the water breaking prematurly and other problems associated with things not being held together so snugly.
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The male of the species prefers a tighter fit, and may become less interested in courting the female.
Both would diminish our capacity to be fruitful and multiply.
My understanding is that if the females hips were any wider, she would not be able to walk upright…and while the image of all the women in the world on their knees might excite some, I prefer them to be nice and tall. 
Scylla, Love the “lower lip” quote, but I thought it belonged to Carol Burnett.
This is a common misunderstanding of the way natural selection works. It would be true only if women with bigger hips tended to have more surviving children because it was easier for them to give birth. I doubt whether this is the case
Just to reiterate what galen said: there is almost certainly no selection pressure to widen women’s hips.
Even if modern medicine didn’t remove much of the dangers to the line, there wouldn’t be selection pressure to widen hips, since the “tradeoff” is between the added fitness due to brain size at birth, vulnerabilty at birth and gait. Natural selection does not act to remove pain, it is pitiless.
picmr
How do ‘they’ know how much pain other mammals experience? I’ve seen my father-in-law hook a chain to a calf’s leg and pull it out. It was neither a pretty site nor pleasant for either party, I assure you.
The cow didn’t have to curse at me and blame me for everything since Pearl Harbor to show she was in pain. 
I believe Cosby, in Himself, references Carol Burnett’s quote and later in the act, he uses it as a gag by describing his wife (in hard labor) standing up in the stirrups, grabing his lower lip and yelling “I WANT PAIN KILLER!” (paraphrased) 
Didn’t evolution make it more difficult because God said childbirth should be painful in Genesis??
Zev Steinhardt
Many animals have pain during childbirth. Just because they don’t yell and scream doesn’t mean they are not in pain.
We are not aware of all the steps it takes for us to have live births - and those steps don’t begin with us. We share the same hormones and many of the body parts that other animals have. We share the production of immature young (smaller size newborn) with most if not all other animals. And we share differences between the sexes that make birth easier for the female that goes right down to bone structure.
However, we are the only ape, chimp, monkey that needs to have the baby rotate and flex during the birth process.
At some point in our history we must have had a great many maternal deaths to get this balance of hip, fetal head and walking well enough to keep up with the group just exactly right.
I think the selection pressure to widen female hips took place long ago.
I have a slightly better one than Ms. Burnett:
“To duplicate the childbirth experience: Insert car jack into rectum and inflate to full height.”
Well, the quick answer is that childbirth is painful because of the muscle contractions involved and the tight fit of infant’s cranium through mother’s pelvis. Pathologists can determine if a woman whose remains they’re looking at has given birth by checking for scrapes on the interior of the pelvis. Ouch.
According to time.com, the rate of mortality for birthing mothers in Rwanda is currently 1 in 12. Infant mortality is 1 in 8. Now, the medical conditions in that country are beyond appalling and as such are probably much more realistic as to how well bipedalism and childbirth go together than the cheery picture we get with immediate medical intervention available.
If there were no medical intervention, then the exigencies of natural selection would ensure that in time we would evolve so that giving birth were not so very dangerous. This, of course, is assuming that maternal and infant mortality are traits that cannot be passed on genetically.
A couple of notes to add to this…people were correct in noting the effect of the baby’s head size. Also evolution was brought about narrower hips in humans that allow us to walk upright. This combined effect results in a square pegs in round holes phenomenon. Although much of the pain comes from contractions (which are no fun) some of it also comes from a dislocation of the pubic bone from the hips, which allows the baby’s head to fir through (so in effect the mother’s hips work like the jaws of a snake). Probably evolution will see hips get narrower if anything.
As far as other animals feeling pain, they probably do in the contractions, but over all the physical trauma to most animals is FAR less than that in humans. Save for spiders being eaten by their young of course…but generally in most species with live birth, there is much less blood loss, far lower mortality rates, and less distress.
Phouka said:
What would happen, though? Would heads begin to reduce in size? Women’s hips get wider? Or (my guess), births would occur even earlier – say, 6 or 7 months instead of 9.
Actually, the most painful part of childbirth is the dilation of the cervix, not pushing the baby out through the vagina. Vaginas are very elastic and also contain very few nerve endings. The issue is still head size, of course–that’s why the cervix has to open so much.
I also disagree that there will be selection pressure to produce wider hips. Most normal women have perfectly adequate pelvises already and cesarean section takes care of most others.
Looking at mortality rates in developing countries is also tricky. There are many countries with very little medical intervention in birth that have a relatively low mortality rate. Factors like maternal nutrition and stress are probably more important determining factors than body design.
Milo, I couldn’t tell ya. I don’t know enough about biology or genetics or evolutionary mechanics to make even a WAG.
Cher, you make an excellent point about the mortality rates. Since this is Rwanda we’re talking about, malnutrition and stress definitely play a role. However, about the possible evolution of hip bone structure, I will make a WAG and say that without continued medical intervention the average pelvic canal (what’s the accurate name for that?) would increase on size simply because the women who today require caesarians to give birth wouldn’t survive unaided childbirth, and their babies would most likely die with them.
Gruesome topic, isn’t it?
Asmodeus posed the question: “Why is childbirth painful?”. Then in the OP, said “I don’t mean physically…”. What do you mean?
I can’t resist quoting Tim Allen’s character in Home Improvment. He said to his wife: “Yeah, don’t forget it was painful for me too. All that screaming hurt my ears!”