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While googling around the Internet I found an article by Steven Kotler on the Psychology Today blog entitled "How We Learned To Walk: The Uneasy Origins of Rock Climbing". Talk about a surefire, catch-Clink's-attention title!
The article reviews anthropology finds over the years and talks about a new theory of human evolution, specifically how humans began to walk upright. Anthropologists once thought humans started walking upright after they came down from trees. Now primatologists are suggesting that walking is a natural offshoot of climbing. They site orangutans who have been observed "tree walking", or walking across branches while holding an upper branch with both limbs (a bit like a toddler 'cruising' while holding on to furniture). This climbing method is energy efficient and stable because it allows for four points of contact at all times---it also happens to be the way a beginning rock climber climbs.
OK, so it's a bit of a stretch (literally) but at least it gave me a chance to link some of my favorite subjects together in one post.