You're looking fine Lucy--Perhaps this is how hominids learned to walk.
by phil on Friday Mar 5, 2004 9:32 PM
Humans evolved the ability to walk upright because of its social benefits. Good posture, the development of larger brains, increasing group size, and the complexity of human tribes, all evolved in tandem between four and two million years ago, and thus there is a common story running through those features. Walking upright fits in because it projects more information about the hominid. Rather than having heads toward the floor, focused on an individual ape's consumption of flora and fauna, the upright Adripithecus is instead concerned with a conversation with his fellow hominids. Posture is tantamount to connecting with others: shaking hands, kissing, sharing tools, hugging, and spooning.
These ideas come from Neil Robert Miller's rambling, but provocative, essay On Upright Walking - Posture, Affection, Cognition, Intelligence, Solving
Other competing theories for how we got "bipedalism" involve the following:
- Standing tall above the grass, early hominids could better find prey.
- So as to hold javelins better.
- In the hot African sun, standing tall provided thermal benefits. Sunrays would come at an angle rather than dead on the back of an ape, and the single bed of hair on the head blocked most of the sun, while as the lack of body hair enabled cooling. Plus, they could always turn their bodies if one side was getting too hot.
I doubt these arguments because I don't believe in the centrality of "survival and reproduction of the fittest" argument in evolutionary biology. Sure "Survival of the Fittest" is the overall grand evolutionary engine, but more powerful auxiliary evolutionary technology developed on top of natural selection to give evolutionary arcs advantages over other arcs. For example, humans, reptiles, birds, and fish all share the fundamental feature of bones. In fact, comparisons of the human fetus in various stages of development look shockingly similar to the development of other animals--tails, gills and all. So the technology that has been abused since the Cambrian Explosion is not mere "natural selection" but the "reconfiguration of the skeletal template." Through sexual selection, a small preference for above-average (or below-average) sizes of certain bone structures can rapidly reconfigure the shape of members of a species.
In the case of walking upright, sexual selection may have had a preference for socially adept hominids. This is certainly the case today, as anybody lacking charm or money (a social skill as it involves creating value in the eyes of other humans) is on a path to reproductive doom. So on the Serengeti, lines of hominids that had strong preferences for social hominids had ever inflating social networks and thus, survival benefits over others.
Simple "natural selection" alone has seemed too slow to account for the complexity of the eye. Embedded within natural selection, though, is a deeper hierarchy of mini-natural selections, involving competing technologies like "skeletal templates," "network effects," or whatever hidden code modules are in DNA. There must be a larger invisible group of actors behind what can be seen in fossil records to explain the vast complexity of Earth's biology. Otherwise, simply mutating genes--which is like playing the lottery--and then perpetuating the best mutants' children, would take trillions of years, not four billion.