Progress, Ladies...

 ...Says here that Naked Ape scientists are starting to (dimly) understand HOW IT WORKS when their people, or subsections of them, make detectable moves to ENTER THE SEA FOREVER.   Of course, this method of becoming more aquatic is only one way of doing it, but it's well known to be EFFECTIVE and pretty PERMANENT. One of the very few FAILURES in the whole of the planet's history is the featherless biped or Homo sap, who started to become aquatic many generations back, and them just QUIT when a certain inland sea dried up, instead of FOLLOWING THE WATER.

But as we can see here, some of them are STILL WORKING ON GETTING BACK WHERE THEY BELONG.  Good show.