Baboon moms carry deceased infants for up to 10 days

Scientists documented baboons mothers in the wild in Namibia carry dead infants for up to ten days. Photo by Alecia Carter/UCL

March 11 (UPI) -- Wild baboon mothers carry dead infants for up to ten days, according to a new study. The research promises to illuminate the ways animals deal with death.

Over the course of 13 years, scientists observing wild Namibian chacma baboons documented group responses to 12 infant deaths.

Chacma baboons live in mixed-sex groups ranging in size from 20 to 100 primates. The groups are organized by strong linear male and female hierarchies.

Scientists observed mothers carrying dead infants for as little as an hour and as many as 10 days. Mothers carried their dead infants for an average of three to four days. The research team published their observations Wednesday in the journal Royal Society Open Science.

"There are numerous hypotheses to explain primate responses to dead infants," lead study author Alecia Carter, anthropologist at the University College London, said in a news release. "Perhaps the strongest hypothesis is that carrying after death is an extension of nurturing behavior."

Scientists watched baboon mothers carry deceased infants by a limb and dragged them along the ground, behaviors never seen with live infants.

"We are not suggesting that the mothers are unaware that their infants are dead, but there is such strong selection on mother-infant bond formation that, once formed, the bond is difficult to break," Carter said. "It's less clear why only some mothers carry or protect their dead infant, but I suspect that a range of factors influence this behavior."

According to Carter and her colleagues, the "grief-management hypothesis" best explains the behavior. According to the hypothesis, carrying a dead infant is a way of coping with the emotional impacts of a tragic loss. The "social-bonds hypothesis" suggests baboon mothers hold onto their dead infants due to their intense social bonds with their young offspring.

Scientists suspect a range of factors account for the range of time that mothers carry their dead infants, including the mothers' age, the cause of death and the climate conditions.

"Other primates have been observed carrying their dead infants for much longer periods of time," Carter said. "Chimps and Japanese macaques for example have been observed carrying infants for over a month. However, chacma baboons travel much longer distances on an average day and the desert environment is harsh, making it costly for a mother to carry her infant for long periods."

Researchers also observed the fathers of dead infants protecting the corpse and sometimes grooming the dead infant when the mother wasn't nearby.

"This is quite surprising behavior, because it has rarely been reported by previous studies," said co-author Elise Huchard, a researcher at the University of Montpellier in France. "Male baboons are not usually very paternal, but they regularly protect their infant from threats, especially from infanticidal attacks. That is where a male baboon kills another male's offspring in order to mate with the mother."

Scientists hope their findings can help researchers begin to answer questions about the origins of humans' awareness of death and dying, and perhaps even the evolution of consciousness.