PLoS One 4, e4156 (2009)

Certain versions of a key gene for the brain regulator serotonin disproportionately predispose those with a history of childhood abuse to depression and alcoholism.

Rhesus macaques and humans have similar variation in the serotonin transporter gene. Work by Karli Watson of Duke University in Durham, North Carolina and two colleagues shows that the animals show similar behaviour if they possess one 'short' version of the gene. These macaques demonstrated the simian equivalent of social anxiety by avoiding looking at pictures of faces, and particularly avoiding looking them in the eye.