The Aquatic Ape: A Theory of Human Evolution written by Elaine Morgan is an interesting book about human evolution with an unique twist.
Imagine, if you will, in the course of human evolution, what if man had to adapt to an aquatic existance for a period of time before again returning to land. This is the theory put forth by the author. This theory was first propounded by Professor Alister Hardy. He laid the foundation for his theory by comparing man to other animals and asking questions. Some of these question were very basic, why does man walk upright, why is man naked, why does man have an aquired language, why does man shed tears, and why does man have a different sexual behavior than other primates. All of these questions and more are basic to evolution.
Now, if you compare man to aquatic mammals, these questions will start to have answers in comparative anatomy. But, where to you find the evidence to link an aquatic adaptation in man's past? Well, the author does some good ol' detective work and came up with some answers. There are parts of Africa, more precisely the Nubian, Arabian, and Somalian plates around the Red Sea and Gulf of Aden.
I found the book to be an easy well-written read that is engagingly clever. But, the questions that it raises have answers that are very compelling to the theory of some aquatic evolutionary history, which is hard to iqnore.