Washington [US]: Young babies emit a lot of squeals, vowel-like noises, growls, and brief word-like sounds like "ba" or "aga." These "protophones," or predecessors to speech, are gradually replaced by early words and, eventually, entire phrases and sentences. While some newborns are inherently more "talkative" than others, a recent study published in iScience indicates that there are disparities in the amount of noises made by males and females.
In general, they found that male infants "talk" more than female infants in the first year. While the research confirms earlier findings from a much smaller study by the same team, they still come as a surprise. That's because there's a common and long-held belief that females have a reliable advantage over males in language. They also have interesting implications for the evolutionary foundations of language, the researchers say.
"Females are believed widely to have a small but discernible advantage over males in language," says D. Kimbrough Oller of the University of Memphis, Tennessee. "But in the first year, males have proven to produce more speech-like vocalization than females." Male infants' apparent early advantage in language development doesn't last however. "While boys showed higher rates of vocalization in the first year, the girls caught up and passed the boys by the end of the second year," Oller says.
Oller and colleagues hadn't meant to look at sex difference at all. Their primary interest is in the origins of language in infancy. If they'd had to guess, they'd have predicted female infants might make more sounds than males. But they got the same result in an earlier paper reported in Current Biology in 2020.
In the new study, they looked to see if they could discern the same pattern in a much larger study. Oller says that the sample size in question is "enormous," including more than 450,000 hours of all-day recordings of 5,899 infants, using a device about the size of an iPod. Those recordings were analyzed automatically to count infant and adult utterances across the first 2 years of life. "This is the biggest sample for any study ever conducted on language development, as far as we know," Oller says.