human evolution

Grandparents often help out with homework, baby-sitting and cooking. Historically, that elderly help and care might have given the grandkids an evolutionary payoff — the longer-lived, the better.

In his book Sapiens, Yuval Noah Harari packs the history of humanity into 400 pages. "In some areas we've done amazingly well," the historian says. "In other areas we've done amazingly bad."

From an evolutionary standpoint, flavor has long helped define who we are as a species, journalist John McQuaid argues in his new book, an exploration of the art and science of taste.