Boys coo, babble and generally make more noise than girls during the first year of life, new research shows. The reason, it is speculated, could be that boys have developed a greater capacity for sound to help them survive their first year.
In a new comprehensive study at the University of Memphis in Tennessee, researchers used an algorithm to review a dataset of more than 450,000 hours of continuous audio from 5,899 infants. The sounds were recorded with an iPod device over two years.
– This is the biggest sample for any study ever conducted on language development, as far as we know, Professor D. Kimbrough Oller says.
Babies as we know do not speak, but instead produce a lot of other sounds. They coo, scream or make different types of vocalizations, for example. It has long been thought that girls develop language earlier than boys, but this study shows that the opposite is actually true.
Boys made ten percent more sounds in their first year of life than girls, the study found. Girls then caught up in the second year, making seven percent more sounds than boys.
In general, parents spoke more often to the girls, but this had no effect on the number of sounds the babies made. The researchers’ one theory was that boys were noisier than girls because they were more active, but this theory seems unlikely because during the second year the girls caught up even though the boys were still more active.
The researchers instead believe in an evolutionary theory where it is already believed that babies make different sounds to signal their well-being to their parents, in order to get more attention and thus have a greater chance of survival. In general, boys have a higher mortality rate during their first year of life and this may be why boys have “learned” through evolution to be more vocal. On the other hand, the mortality rate drops significantly in the second year of life, which could explain why boys slow down then, it is speculated.
The next step in the research will be to look at how caregivers react to babies’ sounds.