Infants born to older mothers are less likely to get hurt than those born to younger mothers, reveals a long-term study of aggression in lemurs.
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.
The results suggest that infants born to older mothers are less likely to get bitten. It may be that older moms are better at fending off attackers or protecting their infants during fights, say researchers at Duke University and the National Center for Scientific Research in Montpellier, France.
The study will appear online in the December 18 issue of the journal PLOS ONE
In most animal societies, males are the more aggressive sex. But in lemurs, females can be bullies too, explained co-author Marie Charpentier of the National Center for Scientific Research in France. Female lemurs compete with one another for first dibs on food and chase away males at mealtimes, sometimes lunging or snapping at each other with their sharp canine teeth.
To tease out the factors that influence who gets hurt when ring-tailed lemurs tussle, Charpentier and Christine Drea of Duke University combed the animals' medical records for evidence of bite wounds.
Animals at the Duke Lemur Center live outdoors for much of the year in large forested enclosures ranging in size from 1.5 to 14 acres. In these natural habitat enclosures, ring-tailed lemurs live in mixed groups of males and females who are free to forage, interact, play and move around as they would in the wild, providing a unique opportunity to study lemur social dynamics.
Any victims of serial bullying are removed from the group to prevent additional injuries, and all wounds are recorded and treated by veterinarians. As a result, infant mortality for ring-tailed lemurs at the Lemur Center overall is about half of what it often is in the wild.