Some primate mothers kill their own babies

June 9th, 2011 - 4:05 pm ICT by IANS  

London, June 9 (IANS) Some primate mothers, who cannot raise their infants without help from male group members, commit infanticide when stressed and competing with other females.

“Infanticide is an extreme behaviour, and in most species is used by males to eliminate competitors and make females become sexually receptive more quickly,” said Yvan Lledo-Ferrer, study co-author and psychology researcher at the Autonomous University of Madrid (UAM).

However, in callithrix primates, the primate family that Saguinus mystax belongs to, it is the females that perpetrate infanticide.

“Genetic analysis enabled us to show that the mothers themselves take the lives of their own offspring,” said Lledo-Ferrer, reports the journal Primates.

An explanation is that the callithrix are a very unusual kind of primate. They have a cooperative baby care system, in which all the members of the group participate, and in raising infants the whole group must work together to make it successful.

The study observed three groups of moustached tamarins in the Peruvian forest from 1999 to 2008 to determine how help from male members and the absence of competition between females helped to ensure the survival of infants, according to a UAM statement.

The results show that 75 percent infants survive when at least three males are helping, but only 41.7 percent survive if the group has one or two male helpers.

Regarding competition with other females, 80 percent of infants die at less than three months of age if there are two gestating females in the group. This figure falls to 20 percent if there is only one reproductive female.

“Normally, if infants fall to the forest floor from a height, the group keeps picking it up until the infant no longer has the strength to hold on to its carrier’s back. At that point they abandon it on the ground.”

“However, in one of these cases the mother killed her own offspring without it having followed the normal pattern of falling to the ground,” Lledo-Ferrer explained.

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