Non-human apes don’t need a tool to carry their infants in part because they have body hair for their infants to cling to but it’s more complicated than simply having body hair and a baby that can grasp it.
Human feet are unique in the ape family, made for walking instead of grasping. For our babies this means two fewer grasping limbs to help cling to their mother, which means that during the evolution of bipedalism, infants had a harder time hanging on. How did our ancestors survive?
It’s not just that human babies are helpless at birth, it’s that they’re so huge, at least when we compare them to the size of other apes’ newborns. Fortunately we have all kinds of technology to help us carry them around. But how far back in history were our evolutionary ancestors dealing with these big babies?
Why is it that some mammals can just leave their babies in a den or nest, while others carry theirs around (or have them cling on) through out the day?