It seems like so often, and really more often than not, I hear about births having so many things go wrong with them. Why does it seem so hard for humans to hear have a normal birth with a healthy baby?
In: Biology
Because humans have incredibly large heads because of our large brains. Some evolutionary biologists even believe that the width of the birth canal is the main limiting factor to our collective intelligence. Basically, if our brains got any bigger, women would rarely survive childbirth at all.
A lot of it has to do with the evolutionary tension between two of our biggest advantages — bipedalism and big brains.
Being bipedal requires narrower hips. Women have on average wider ones, which is why they have a “feminine” gait. But that leaves room for a smaller birth canal. That limits head size, which in turn limits brain size.
Humans have evolved a few ways to squeeze marginally more brain through a small birth canal. These include a women’s pubic symphasis (where the hip bones join in the front) actually stretching open a bit in birth, and of course babies having squishy heads.
But this push-pull between being a biped and the advantage of large brains means that historically women suffered mightily until modern medicine. Birth is incredibly dangerous for our species and it is estimated that around 1/4 of women who survived to adulthood died from complications from childbirth.
I think it’s because pregnancy and delivering a baby are a miracle of nature. There is so much that could go wrong, it is very likely something does go wrong, from some minor tearing to death. I believe it is the same for animals, humans just get better healthcare and tell you about it.
The delivery will always be a bit traumatic, it is something you will n never forget. For me, it was also totally worth it, to be able to hold my newborn little miracle.
Also, you are more likely to hear the story of a complicated birth told more than once, so it seems there are more complicated births than uncomplicated ones.
> I hear about births having so many things go wrong with them
You are more likely to hear about a birth that had problems than to hear about one which went flawlessly. What is there to talk about if everything went completely normally and uneventfully? You don’t hear very many news stories about stretched of highway where there were no accidents, or neighborhoods where there were no house fires, etc.
Now, humans do actually have a relatively difficult time giving birth. This is because there are two major competing factors in human evolution, the benefits of being able to walk upright which favors a narrow pelvis, and the ability to think and use tools which favors a large brain.
But, the brain goes inside a skull which must pass through the pelvis at birth! So these two factors are at odds with each other, and something has to give. Human children are born relatively undeveloped and grow up outside the womb, increasing their head size after having passed the pelvis challenge. Things are still pushed to the limit though, making human birth as painful and dangerous as can be offset by the other benefits.
Bear in mind, plenty of animals also have complicated births and many mothers and babies die. This varies a lot by species (example: about [60% of hyena babies die during birth](https://africageographic.com/stories/good-bad-gory-birth-hyena-cub) and a lot of mothers die as well). I’m not sure where exactly humans are compared to other species, but we are not a *huge* outlier. But you don’t hear about this very often unless you are some kind of conservationist or farmer.
Humans evolution is an ongoing tug of war between the most efficient body and the biggest brain (and skull to put it in).
The efficient body wants to have narrow hips, small body cavities and short pregnancies.
The big brain wants to have big heads coming through big holes after long pregnancies.
Humans are currently at an uncomfortable compromise.
Babies have heads basically as big as they can possibly be and pregnancies as long as they can last… While still being able to leave through the front door at the end.
Problem is, it’s still a very tight fit and even a little deviation from this compromise causes problems.
Too early? Brain and lungs won’t be ready, baby will be premature and we didn’t evolve to continue prenatal development after birth.
Too late? Baby won’t fit properly on the way out, can start getting tangled, deformed or misaligned on the inside.
Look at animals like rats which are born with their eyes and organs only half developed but have great survival instincts and skills from birth, or look at animals like sheep which are born able to walk and run… But are incredibly stupid beasts.
Humans tried to find their own tradeoff and the answer is crazy, risky, births.
I recently read that until like the 15th century women almost never gave birth lying on their backs. There were standing. Squatting and kneeling positions that were quite common.
But this one king thought the miracle of birth was hawttt. So he forced his lovers to birth on their backs where he had a largely unobstructed view of the events.
And it caught on because the peasants wanted to be like the royals. And just kind of became the default from there.
You do see these older positions used still, especially during more difficult births or when working more with midwives than obgyns.
In addition to what others have said, the average maternal age has increased tremendously in the last century, leading to more complications. Plus medical interventions like c-sections are very common now, over 30%.
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