I have heard the theory that HomoSapiens (or a distant ancestor) returned to the water at some point during our evolution. This is supposedly supported by vestigal finger- and toe-webbing, noses that channel water away, and our hair follicles all following the flow pattern of water over our bodies. So, did we go the way of the dolphin for a while?
Ah… the Aquatic Ape Hypothesis.
A controversial theory to say the least.
Here is a site with lots of links, mostly in support of the theory.
For what it’s worth, The Aquatic Ape by Elaine Morgan makes for very entertaining reading, if not 100% convincing. There does seem to be a fair amount of circumstantial evidence in favor of the hypothesis, but it’s all rather unsatisfying. I like to keep an open mind, but not so much that my brains fall out.