We are at our cutest as infants. We’re most helpless then, too. But every infant has a help button: Cry, and most likely any adult within earshot will rush over to hold and soothe them with a gentle song.
Other primate species, including chimpanzees and macaques, also cradle and carry their fussy young. But human caregivers do something extra. “We added the singing,” says psychologist Sandra Trehub, professor emeritus at University of Toronto Mississauga.
No one knows when parents first sang to infants, but the practice is ancient and universal. “There seems to be evidence of singing to infants throughout recorded history,” says Trehub, who has studied musicality in infants and children for decades. All human cultures perform songs specifically for babies — so-called “infant-directed songs.” Simpler, slower and repetitive, these lullabies seem to soothe distressed infants better than other song types.
But how — and why — did humans create infant-directed songs?