Changes

"Natural selection" was [[Charles Darwin]]'s explanation for how a more complex species supposedly evolved from a less complex one.   

"Natural selection" is the mechanism by which biological complexity and adaptation arises.  It was first proposed by [[Charles Darwin]].   

Specifically, Darwin claimed that a mechanism of survival-of-the-fittest enabled more advanced and more complex members of a species to survive while the weaker ones would die off.  Somehow more advanced members of a species could then produce entirely new species, though there is no evidence of that and no one has explained how that could ever happen.

Specifically, Darwin pointed out that a mechanism of survival-of-the-fittest enabled more advanced and more complex members of a species to survive while the weaker ones would die off.