I was thinking maybe millions of years ago there was a monkey-like creature born to a species of tree dwelling monkey-like creatures that through a genetic defect somewhere in his upper body didn't have the strength to grasp the limbs and swing around in the trees and pick his own food to eat so he was forced to live on the ground around the tree, eating whatever discarded remains of food he could find amongst all the feces. If his fellow creatures had had intelligence enough they probably would have either pitied or loathed the disabled one never realizing that the whole future of the species would come to revolve around walking around on the ground, and not living in the trees.
It seems that there have been at least a couple modern humans born with not a physical defect but a mental one where they are born without the usual survival instincts like wanting to dominate over others or even the desire to reproduce sexually. The two that come to mind are Jesus and Buddha. So they live at the base of the tree as it were by their lack of the usual instincts that all the other humans have in common living only off what's given to them by the other humans. But anyway maybe like with the monkey-like creature the lack of the ability to thrive as the others of their species do has a beneficial side-effect to the future of the evolution of the species just as not being able to swing from the trees did a long time ago.