"When you line up the skins of the over 290 species of ape, the human skin stands out as the only skin which isn't covered by fur"
Desmond Morris, The Naked Ape, 1967
That's the opening line of this, well, amazing book I lately borrowed from my school library. Although from the 1960's, don't get me wrong, it's written in awesomely understandable English (technical enough to get across its points, but nothing that your average guy couldn't understand without a few moments thinking) and tries to explain from an evolutionary/natural point why people are so different from other monkeys. It's supposedly the "basis" of modern anthropology (or study of societies), and honestly it manages to make sense out of a lot of stuff.
Ever wondered why guys get so obsessed over boobs or why black people tend to have bigger lips? Both are sexual signals according to The Naked Ape. Boobs increase stimulation, bigger lips because when the skin is dark you can't use red lips as an effective signal, instead they just get bigger to compensate.
The chapter on sex is honestly pretty large (people apparently are hornier and complex sexually than all other animals) and since I take my time reading books I've only finished the first two chapters. The book however, to try and be objective, treats humans as a "specimen" to be researched. So it's really objective and blunt. But logical. So if you find the idea interesting then read it, but if you think as a species we have "super awesome reasons for doing stuff" then you might get offended.
nota: not trying to convert anyone, just figured some ppl on this board would find it interesting/a recent other topic here made me think of posting this