why is childbirth/labor so long for humans compared to other animals?


Is it because of the whole big head/bipedalism thing? Other mammals can pop out babies in no time and it seems like that would be way more advantageous for multiple reasons (less stress on mom and baby, not in a vulnerable position for hours in the wild, etc). Why does the norm skew towards a day rather than hours?

In: 419

It almost all comes down to our upright posture combined with our high intelligence.

Our high intelligence requires a big brain, but our upright posture requires relatively narrow hips or else it is very difficult to walk.

So the current situation of having very difficult childbirth is essentially an evolutionary compromise between those 2 requirements.

Two big reasons.

1. We are bipedal. Our skeletal system has evolved to better support standing on 2 legs, but that makes it worse for childbirth.

2. Our heads are huge. Human children are born earlier in their development cycle compared to other mammals (most mammals can get up and move within minutes of being born, humans take months). This is because any later and our heads wouldn’t fit. As it is, our heads are still huge coming out, and that makes it difficult.

You are right about the big head and bipedalism which both makes child birth much harder for humans then other animals. And this would indeed make it quite hazardous for humans to give birth in the wild. Not only would it attract predators but infections are much more likely as well. And even just the exhaustion from the event might prevent someone from gathering food and water to survive and recover.

So human child birth is only possible in an intelligent species with social structures and planning skills. The rest of the family group is needed to protect the mother and child and provide for them during the process. Some of these intelligence traits likely evolved first which favoured people with larger heads capable of standing better as the survivability of complex births went up which again allowed people to be smarter and work better. Even though there are some branches on the evolutionary tree of humans compared to a lot of other animals the evolution have been very straight forward with people being smarter and smarter for every generation. Other animals have just not gotten into this intelligence niche which humans have evolved into.

It is not quite true that humans are the only animal with such complex births though. Although the other animals with such hard births are bred by humans. Some species of cattle and sheep are completely unable to give birth without human intervention.

Because we walk upright and have large brains.

Walking upright requires that we have narrower hips, which means narrower birth canals.

Large brains mean we need big heads, which are hard to push through a narrow birth canal.

This is also why human children need so long to develop. Our brains can’t fully develop in the womb like other animals because then our heads would be too big to fit through the birth canal.

One additional thing that people are missing, modern birthing, especially in Western countries, is set up for the birthing DOCTORS comfort not the birthing parent(laying down in stirrups so the doctor can sit and watch the birth happen). When people give birth in a squat position it’s generally a faster and smoother birth.