Lemur babies of older moms are less likely to get hurt. Duke Today, December 18, 2013. A long-term study of aggression in lemurs finds that infants born to older mothers are less likely to get hurt than those born to younger mothers. The researchers base their findings on an analysis of detailed medical records for more than 240 ring-tailed lemurs — cat-sized primates with long black-and-white banded tails — that were monitored daily from infancy to adulthood over a 35-year period at the Duke Lemur Center in North Carolina. It may be that older moms are better at fending off attackers or protecting their infants during fights, the researchers say.