Who has the easiest time giving birth? It isn't humans. We compare childbirth of animals to humans to figure out what makes it so painful for humans.
In pigs, a full-size sow might weigh 600 to 800 pounds, but her piglets might weigh only about 1 pound, or less than 1 percent of her weight.
An in-depth article on the bbc.com/earth website says that anthropologist Sherwood Washburn proposed the answer to obstetrical dilemma in 1960, and it stuck for a long time: female hominids had to maintain a narrow pelvis with a constricted birth canal in order to walk efficiently on two legs. But foetuses were evolving to have larger heads, which were a tighter fit through the narrow pelvises.
This premise has been examined and challenged over the years and what has emerged is the following:
With the study of fossil records, it seems that some earlier species of human, including Homo erectus and even some Neanderthals, had a relatively easy time of it when it came to giving birth.
That's according to Jonathan Wells who studies childhood nutrition - he thinks childbirth might even have been a relatively minor problem in our species – at least to begin with. There are very few newborn baby skeletons among the human remains from early hunter-gatherer groups, which might hint that death rates among newborns were relatively low.
So what does he propose? The change came with the move to farming.
"There is one striking feature archaeologists have noticed when comparing the skeletons of early farmers with their hunter-gatherer ancestors. The farmers were noticeably shorter in stature, probably because their carbohydrate-rich diet was not particularly nutritious compared to the protein-rich hunter-gatherer diet."
In general, the shorter a woman, the narrower her hips. So the shift to farming almost certainly made childbirth a little bit more challenging.
Wells adds: the carbohydrate-rich diets that became more common with farming can cause a developing foetus to grow larger and fatter. That makes the baby harder to deliver.
Combine these two factors and human childbirth – which might have been relatively easy for millions of years – suddenly became more difficult about 10,000 years ago.
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