How laughter evolved and how it makes us human

Grins and giggles may hold the key to our social evolution.

Blaine Greteman | August 2009 issue

Photograph: Corbis Photography

Two Neanderthals walk into a bar, order drinks, sit down and listen to the chattering, laughing crowd. Suddenly, one turns to the other and whispers, "Try to stay cool, but this sounds like one of those Homo sapiens joints."

How would a Neanderthal know he was in a Homo sapiens joint? Laughter. In a Neanderthal bar, after all, one might have heard plenty of grunts and snorts, but presumably fewer giggles, since that staple of barroom banter—the laugh—hadn’t yet evolved in its current form. Today, we tend to focus on "he who laughs last." But he who first burst forth with our characteristic "ha-ha-ha" took a major evolutionary leap toward humanity as we know it.

Laughter is ancient, predating the development of language. It’s ubiquitous; all mammals do it, in one form or another. Chimpanzees do it, panting with delight in response to tickling or pratfalls, as noted by none other than Charles Darwin. It’s also one of the first things babies learn. Now, though, scientists are asking two dead serious questions: Where does laughter come from? And why do we do it?

Recent studies suggest laughter evolved between 2 and 4 million years ago, after we learned to walk on two legs but before we could speak. For our hominid ancestors, laughter may have signaled safety and facilitated group interaction, making human society possible—just as it does today.

Dacher Keltner, a psychology professor at the University of California, Berkeley and author of Born to Be Good: The Science of a Meaningful Life, compares laughter to the evolution of tool making or opposable thumbs—the "signature of a great shift in our social organization." No matter how much you tickle a lizard, notes Keltner, it won’t guffaw, chuckle or even purr. "One of the unique characteristics of mammals is that we play," he says, "and as you get more complicated in the mammalian structure, you have a greater vocabulary of play, including laughter."

Our closest mammalian ancestors, apes and chimpanzees, both laugh, though probably not at the same things we do. When apes play, they roughhouse, tickle and laugh, although few of us would mistake an ape’s cackle for the human equivalent.

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