Currently, sloths have a hard time walking on land because they are slow and their hands are not shaped for walking. But, sloths have an easy time hanging from trees and moving around that way. In 1000 years, there will be less trees for sloths to hang off of, so they will need to be able to move around on the ground easier. In 1000 years, sloths will have an extra bone in their hands and feet that makes them capable of bending them, making it easier to walk. The way that this will be achieved is that there will be a mutation in a family of sloths that forms an extra bone. The sloths that have an extra bone will live an easier life, causing the other sloths to die out. Then, the mutated sloths will have offspring, making the whole population of sloths with extra bones.
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