Theory that humans underwent a semi-aquatic phase at some point in their evolution. First proposed by Sir Alister Hardy in the 1950s, and taken up in the 1970s by Elaine Morgan in books such as The Descent of Woman and The Descent of the Child. Sometimes known as AAT.

A highly plausible and convincing theory to some, a load of nonsense to others. Has gained many adherents but is by no means the majority view, which is still basically that we came down from the trees in the savannah and learnt to throw things and became hairless for some such reason.

The beach-dwelling phase, if it occurred, probably occurred while we were all on the shores of the Red Sea or some such environment, but one of the biggest problems of the AAT is that no precise sequence in the fossil record, or gap in it if a gap is needed, can be pointed to as exactly the right time for the phase to have occurred.

Evidence for, not all of which needs to be correct or convincing for the theory as a whole to be believable:

And no doubt more that I or someone could list (along with the inevitable vitriolic attacks)...