The complete title of this book is The Scars of Evolution: What Our Bodies Tell Us About Human Origins (Oxford University Press, ISBN: 019509431X).
An interesting, occasionally quite personal, defense of the Aquatic Ape Theory (AAT); in this view of the origins of men, originally put forth by Alistair Hardy, our species went through a wetland living phase. During this phase, the transition to bipedalism happened, along with a set of interesting changes in the body such as the loss of fur, a transition to frontal coition, a radical change in the quality of our sweat and a change in the distribution of body fat.
This contrasts with the currently prevalent view, in which proto-humans (see 2001:A Space Odyssey) went through a savannah phase. The author's argument is that all the changes in the human body that make us different from apes would have yielded no advantage in a savannah, while being very convenient in a semi-submerged environment like a coastal marsh. Since fact some of the changes lead to clear disadvantages, like a more complex pregnancy, widespread spine problems, complex pregnancy and delivery, the author wants to find out what was the evolutionary tradeoff.
The author, Elaine Morgan, is a gifted writer able to make a very powerful (if non-technical) case for her view of how humans became humans. I personally found it very interesting - my knowledge of the field does not allow me to have any opinion on the merit of the views exposed. It does feel like good science, though, and it made me think. I did not particularly like the part about "it is ok to be fat, because seals are fat", and the tone does occasionally get a bit grating. Overall a very readable book, that reawakens one's faith in science as the discipline that can fix itself.