Human Babies and Chimps Have Something in Common Their Parents Don't Share

This is the 21st most interesting thing we learned about humans this year.

It’s scientifically established that humans and other great apes enjoy a good laugh. We likely inherited the capability to laugh from the last common ancestor we share with gorillas, bonobos, and chimpanzees. But in 2018, scientists discovered that we have more in common with chuckling apes than the same evolutionary origin — in fact, human babies are more like chimps than their own parents.

Well, at least when it comes to laughter. When human adults laugh, they primarily produce sounds as they exhale. At the meeting of the Canadian Acoustical Association in November, a team of phoneticians and psychologists revealed that when human infants laugh, they make sounds both on the exhale and inhale — like a chimp. This means that the giggles of an infant are more analogous to nonhuman primates’ than those of human adults.

Researchers from Leiden University, the University of Amsterdam, and University College London suspected these results would likely emerge because human infants, like non-human primates, tend to laugh in the context of tickling or play. To test this hypothesis, they examined laughter recordings taken from 44 infants between the ages of 3 and 18 months. The laughter recordings, like the ones in the video above, consistently showed that babies laughed on both the inhalation and exhalation — especially the youngest babies.

chimpanzee
Babies laugh more like chimps than humans. 

However, researchers don’t yet know why human laughter changes as we age. The team does have some theories — one idea is that, as humans develop the ability to speak, they way they laugh changes. Another idea is that it’s what triggers the giggles that controls the way they come out. Babies and chimps laugh because of tickles, while adult laughter can be spurred by some pretty dark stuff. It’s possible that laughter caused by various stimuli is produced differently.

“Adult humans sometimes laugh on the inhale, but the proportion is markedly different than that of infants’ and chimps’ laughs,” co-author Disa Sauter, Ph.D., a psychology professor at the University of Amsterdam, said in a November statement. “Our results so far suggest that this is a gradual, rather than sudden, shift.”

As 2018 winds down, Inverse is highlighting 25 surprising things we learned about humans this year. These stories told us weird stuff about our bodies and brains, uncovered insights into our social lives, and illuminated why we’re such complicated, wonderful, and weird animals. This story was #21. Read the original story here.