Lemurs don’t yawn in the face of danger. They wait a few minutes after perils have passed before breaking into breathy mouth gapes.
Lemurs in a southern Madagascar reserve yawned frequently within 10 minutes of fighting with other lemurs, surviving attacks by predatory birds and coming close to snakes, tourists or other potential dangers, primatologist Elisabetta Palagi of the University of Pisa in Italy and her colleagues report August 28 in the American Journal of Primatology.
Lemurs largely stopped yawning after that brief outburst. This pattern held for 13 ring-tailed lemurs and 15 Verreaux’s sifakas tracked daily for three months in 2011.
Recurring dangers that lemurs learn to escape or avoid elicit moderate, brief anxiety, the researchers suspect. Yawning amps up as animals rapidly return to calmness, much as it increases when lemurs take rest breaks during the day, Palagi’s team says. Many physiological and social forces contribute to yawning, they add.