In summary

Now we can understand why human babies are born so helpless. Our babies are born with unfinished brains because the pelvis simply cannot be any wider or bigger or we couldn't walk upright.

The human baby's helplessness, then, is caused by the changes humans have made in the way they have developed. It came about, firstly, because our ancestors shifted from moving around in a bent over position using their knuckles for balance, to walking upright on two legs. The second reason was that the baby had to be born when the brain was still small and underdeveloped to be born through the mother's narrow birth canal.

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