I’m going to tell an untoward story of transportation and motherhood, which calls back to my experience in evolutionary biology, and forward to my desire to professionally encourage walking. I’d like to talk about what we got and what we lost by walking
Humans are the most upright terrestrial animal species. We are not the fastest runners on our two feet, but we are the furthest walker. Our advantage was stalking prey over long distances. This stalking was a lot easier with cooperation between several humans involved in the walking hunt. Communication and clear and complex languages probably evolved as they aided the efficacy of these hunts. Walking upright is aided by our huge butts, strong legs and heavy pelvic bones. Our arms and chest are not nearly as strong as our legs and pelvis, and we walk on our feet while every other non-primate walks on their toes.
While these physiological adaptations make us great hunters, they also make childbirth dangerous for the infant and mother. The mortality rate of humans in childbirth is much higher than for most other primates or carnivorous species. As a compromise, our infants are less developed than infants of most other species upon birth. They require more care. This is another factor that makes social humans living in large groups more fit than asocial ones living in small groups. Mothers had to stick around to raise their tiny kids if they wanted them to survive. And they needed support, the kind of support you would get from a village with a common and complex language.