Human beings are not obviously equipped to be nature’s gladiators. We have no claws, no armor. That we eat meat seems surprising, because we are not made for chewing it uncooked in the wild. Our jaws are weak; our teeth are blunt; our mouths are small. That thing below our noses? It truly is a pie hole.

The title of Mr. Wrangham’s new book — “Catching Fire: How Cooking Made Us Human” — sounds a bit touchy-feely. Perhaps, you think, he has written a meditation on hearth and fellow feeling and s’mores. He has not. “Catching Fire” is a plain-spoken and thoroughly gripping scientific essay that presents nothing less than a new theory of human evolution, one he calls “the cooking hypothesis,” one that Darwin (among others) simply missed.