Poster A sleeping infant
A sleeping infant
Matt Johnson | CC BY-ND 2.0

How lullabies evolved

Why do we sing to babies? To calm them, obviously — but there may be additional benefits that helped humans win the wars of natural selection, two Harvard scholars argue in a new paper published in the journal Evolution and Human Behavior.

Lullabies aren't just for fussy babies, argue Samuel Mehr and Max Krasnow. Yes, they certainly do have a calming result, which in primitive times might have been important to avoid attracting predators as well as to get infants to sleep. Mehr (a graduate student in education) and Krasnow (a psychologist) believe that singing to children could have helped to hold their attention so as to keep them from wandering off or doing other dangerous things.

"Particularly in an ancestral world, where there are predators and other people that pose a risk, and infants don't know which foods are poisonous and what activities are hazardous, an infant can be kept safe by an attentive parent," Krasnow told the Harvard Gazette. "But attention is a limited resource."

Mehr and Krasnow also point out that children have evolutionary reasons to attract and hold their parents' attention, and that a parent singing assures young ones they're being attended to.

There's even a bigger implication of the new theory, though: it might explain the reason that humans are the only musical species. Evolutionary biologists have long struggled to come up with a satisfactory explanation as to why music is so universal among human societies. If Mehr and Krasnow are right about lullabies, it might be that all other music derived from baby song.

"In the past, people have been so eager to come up with an adaptive explanation for music that they have advanced glib and circular theories, such as that music evolved to bond the group," famed evolutionary psychologist Steven Pinker told the Gazette. "This is the first explanation that at least makes evolutionary sense — it shows how the features of music could cause an advantage in fitness. That by itself doesn't prove that it's true, but at least it makes sense!"

Even at this late stage in the evolutionary game, babies — and grown-ups — still love gentle, lilting music. Get your fix any time, anywhere with YourClassical's Sleep stream.

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