Almost all mammals walk on four limbs. Those that occasionally stand or walk bipedally, do so awkwardly and for specific and short-term reasons (i.e., a threat gesture).
Of all mammals, onlyare fully developed bipeds. We do everything (almost) on two limbs. Anthropologists and have come to agree that upright posture is the crucial adaptation that accounts for the divergence of the human lineage from the African apes.
“The fundamental distinction between us and our closest relatives is not our language, not our culture, not own technology;” said Richard E. Leakey, a paleontologist and son of Mary Leakey and the late Louis S. B. Leakey; renowned fossil hunters in Kenya. “It is that we stand upright, with our lower limbs for support and locomotion and our upper limbs free from those functions.”
Why did we rise up? Most paloeanthropologists cite the following reasons:
- to travel distances by walking. Arguably, one of man’s great defining characteristics is his stamina–his ability to travel distances. A locomotion serves that skill better than a one
- carry things, like a child or harvested food
- because it was so hot (Vrba)
- forage from higher food sources
- forage in the savanna, a new food source
- to save energy. It takes a lot of energy to hunt for food. The animal that can do that more efficiently will survive better.
- to cool themselves (the Cooling Hypothesis) in the blistering African savanna
Although I’ve researched all those who should know on this topic (Leakey, Stringer, Tattersall, Vrba, etc), no one mentions that man might have stood to keep food or children from the reach of predators.
I got this idea from my dog. I love Casey. He gambols and prances in a very dogly fashion. He is a good friend and a trusted confidante. But there are times, his enthusiasm threatens a meal I’m attempting to carry upstairs to eat or a pile of papers that need transferring. In those case, I simply raise them (as I’m sure you would do) so the wonderful dog Casey can no longer reach them.
With that came my epiphany. If I do that instinctively, my predecessors probably did to. Once they figured out they could balance well on their hind limbs, what a wonderful way to keep food from others. I can picture a group ofreturning to their home base (for those who believe they occupied a home base millions of years ago) or merely traveling as a group with food. Predators won’t attack a larger group than they are, but they might pick off the weakest, or snag what bits they could. The latter would include food at a quadrupeds” muzzle level, or waist level. If our ancestors could raise their food above that level while beating back the enemy with sticks or growls, that is an effective method of surviving.