“The Professor in the Cage,” Jonathan Gottschall’s provocative new book, locates itself at the gridlocked intersection of biology and culture.

The subtitle “Why Men Fight and Why We Like to Watch” suggests another question, Why are women the nicer sex? and its corollary, Are they really?

The answers are fascinating and complex, though perhaps not as complex as his book makes them out to be.

Part of “The Professor in the Cage” is about how Gottschall, an out-of-shape, disenchanted academic, got involved in the brutal world of mixed martial arts (MMA). His personal story is less interesting, however, than his personal observations. He hits the mark, for instance, when he says that MMA is like gay porn – all those rippling, sweaty physiques grappling with one another in clutches that are at once amusing and arousing. It’s the reason I love wrestling. And I suspect – as the nude wrestling scene in “Women in Love” suggests – it gives men a license to touch one another in a way that conforms to traditional heterosexual society, as do all sports.

But why must male athletic competition be so violent – or at least carry the threat of violence? And why do we secretly – or not so secretly – find it thrilling? ...