TOKYO • A chimpanzee mother cared for her disabled infant in the wild in Tanzania, Japanese researchers reported in a study published this week - research they hope will help in understanding the evolution of social care in humans.

A team of Kyoto University researchers discovered that a "severely disabled" female chimpanzee baby was born in Tanzania's Mahale Mountains National Park in 2011, and recorded behaviour of the group for about two years.

It was the first time that a disabled chimpanzee was observed receiving social care in the wild, noted the researchers.

"The observed infant exhibited symptoms resembling Down syndrome, similar to those reported previously for a captive chimpanzee," read an abstract of the study published on Monday in the online edition of journal Primates.

"The mother's compensatory care for its infant's disabilities and allomothering of the infant by its sister might have helped it to survive for 23 months in the wild" when the infant disappeared and was believed to have died, they said. Allomothering refers to care of infants performed by those other than the biological mother.

The mother and the sister of the chimpanzee supported its body during breastfeeding, said associate professor Michio Nakamura of Kyoto University.

AGENCE FRANCE-PRESSE