When a human baby is born, its first cry is a normal sign of good health. Having never taken a breath before, the baby signals its first inhalation and exhalation-in the form of a screech.
How do babies know to create a sound they've never made before? And is their first yelp truly the start of speech development?
As it turns out, human babies may be practicing how to cry long before they ever make a sound. That is, if they're anything like marmosets, humans' primate cousins. A study of marmosets by Daniel Takahashi, a co-author of the study and an animal behaviorist at the Brain Institute at the Federal University of Rio Grande do Norte in Brazil. shows fetal monkeys practicing crying in the womb. Takahashi notes, "marmosets are monkeys that we know vocalize a lot, and they share a lot of features with humans."
For instance, both male and female parents raise their offspring together, and unlike other primates, marmoset babies are relatively helpless when they're born, like human infants. Takahashi says the central finding will help illuminate when speech development begins, and that studying pre-birth-rather than the moment of birth-may help identify speech or motor development problems earlier.
"There are a lot of things going on in the womb that might be relevant to what's going on afterwards," he says.