If you're good at finding the one right answer to life's multiple-choice questions, you're ”smart.” But ”intelligence” is what you need when contemplating the leftovers in the refrigerator, trying to figure out what might go with them; or if you're trying to speak a sentence that you've never spoken before.

Drawing on anthropology, evolutionary biology, linguistics, and the neurosciences, Calvin also considers how a more intelligent brain developed using slow biological improvements over the last few million years. Long ago, evolving jack-of-all trades versatility was encouraged by abrupt climate changes. Now, evolving intelligence uses a nonbiological track: augmenting human intelligence and building intelligent machines.