This idea was explored over a century ago in H. G. Wells' classic "The Time Machine" (https://en.wikipedia.org/wiki/The_Time_Machine https://en.wikipedia.org/wi

This idea was explored over a century ago in H. G. Wells' classic "The Time Machine" (https://en.wikipedia.org/wiki/The_Time_Machine https://en.wikipedia.org/wiki/The_Time_Machine), in which over time humanity split into two distinct species by the process you describe.