Yazata
Active Member
If we come from monkeys.Why are monkeys not turning into humans still?
Despite the abuse that your question predictably attracts, it's actually a good question. Anybody who really studies the biological sciences will be expected to address questions like that.
I think that the answer is that all of the other simians are reasonably well adapted to their own modes of life. That means that they are successful at what they do and aren't experiencing a whole lot of selective pressures.
As Twilight Hue points out, the evolutionary line that led to humans seems (according to currently accepted hypotheses) to have resulted when our ancestors came down out of the trees and adapted to living on the ground. That resulted in a new form of locomotion (walking) which favored a whole bunch of skeletal changes. It led to our ancestors exploiting new foods and new ways of obtaining it, which favored cognitive changes and changes in sociality.
Meanwhile our monkeyish ancestors were still swinging through the branches of trees and eating what they could gather up there. Their descendants are still doing it. If it ain't broke, don't fix it.
Which raises the question, if the arborial lifestyle was working so well for monkeys, why did our ancestors come down out of the trees? Perhaps the answer is climate change in which African rain forests were slowly transforming into sparsely wooded savannahs. So in the regions where this change was happening, the old arborial lifestyle became increasingly difficult which created an evolutionary incentive we might say to try something new.
I think that many/most evolutionary changes are driven by ecological changes.
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