Grieving female monkeys drink own milk after losing infants

LONDON - In a new research, scientists have observed female monkeys in Morroco suckling themselves, drinking their own milk, in grief after the death of their infants.

According to a report by BBC News, Dr Bonaventura Majolo and his PhD student Richard McFarland noticed the unusual behaviour while studying wild barbary macaques (Macaca sylvanus) living in two troops in the Atlas Mountains of Morocco.

The behaviour, rarely recorded by scientists, may have been exaggerated by grief, as each monkey did it more often after the death of her infant.

By suckling their own milk, the female monkeys may be alleviating stress or boosting their immune systems, scientists speculate.

Together with two field assistants, Dr Majolo and McFarland were studying the behaviour of the troops of the barbary macaque, one dubbed “Flat face” and the other “Large” troop.

“We observed self-suckling by chance while we were with the monkeys collecting data for other projects,” said Dr Majolo.

The scientists first saw four females within the “Flat-face” troop engage in self-suckling while their infants were still alive.

While each female was suckling her infant on one nipple, she would briefly place her other nipple in her own mouth, leaving it there for a second or two.

She would usually then move her infant onto this second nipple.

The scientists suspect this behaviour helps stimulate or improve the flow of milk, helping the infant to feed.

However, soon after, all four females lost their infants. Three disappeared while one female macaque, named “Jessica”, was seen carrying her dead infant for six hours before finally moving on.

After the deaths of their offspring, the four female macaques engaged in much longer bouts of self-suckling, lasting up to two minutes at a time.

Jessica self-suckled for 106 straight days after her infant’s death.

Self-suckling is an extremely unusual behaviour. Before now, scientists have only published accounts of self-suckling in chimpanzees and feral goats.

The behaviour appears to be cultural, as it only occurred in the “Flat face” troop. For example, a female macaque which lost her infant in the “Large” troop at the same time didn’t engage in similar behaviour.

“The most interesting explanation, in my opinion, views self-suckling as related to the emotional consequences of the loss of an infant,” said Dr Majolo.

“In humans and other species, breast-feeding reduces the stress through the release of prolactin. It is therefore possible that the self-suckling functions to reduce the stress generated by the loss of the infant,” he added. (ANI)