adam and eve were apparently "designed" to live in trees

I'm studying skeletal biomechanics right now, and though I tend to have a pretty strong aversion to all things that come in formulas, this stuff is actually pretty interesting. In this lecture we learned that bone tissue is stronger when it is loaded in a more rapid or impulsive manner -- but its failure strain (ability to deform) is reduced at increased loading speed (think of pulling play-doh apart quickly versus slowly: play-doh is stronger if you try to pull it apart quickly but because its ability to deform at this speed is reduced, it is more likely to snap apart if you pull too quickly). This explanation makes sense if you realize that play-doh (and most materials including bone) have some amount of protein in them that is shaped like long strings of spaghetti. If you try to separate spaghetti too quickly, it will break because you don't give the strings enough time to slip apart. The more slowly you try to separate the spaghetti, the less force it will take for you to separate the sphagetti without breaking them. Of course we don't want our bones to bend everytime we take a step, but we also don't want to have them snap the minute we start stepping a little too quickly. So bones need to be made out of materials that allow them to achieve the best balance (for our use) between strength and deformation. Interestingly, it turns out that the bone's toughness (compromise between strength and rate of deformation) is best suited for a fall from a tree.