Levels of a brain protein could help to explain sex differences in some animal vocalizations, including in human language.

In a study of newborn rats, Michael Bowers at the University of Maryland School of Medicine in Baltimore and his colleagues identified a relationship between differences in the level of protein Foxp2 in the male and female brain to the ultrasonic distress calls that pups make when they are separated from their mothers. Male pups — which have higher Foxp2 levels in multiple brain regions — call more frequently and at lower pitches than their female siblings. When Foxp2 levels were reduced in males and increased in females, these differences were reversed. The authors also found sex differences in the protein in human brain samples that correlates with earlier language acquisition by girls.

J. Neurosci. 33, 3276–3283 (2013)