Exactly my thought. Mammals without opposable thumbs or well-developed cerebella can cross large bodies of water, clinging to floating material. I don't see w

Exactly my thought. Mammals without opposable thumbs or well-developed cerebella can cross large bodies of water, clinging to floating material. I don't see why a group of hungry and adventurous proto-humans didn't cross a channel from one island to another. No boat needed. The miracle is that rhino got there. How well can rhinos swim?