TOKYO — Researchers studying a troop of wild chimpanzees in Guinea have confirmed yet another likeness between humans and their close cousins: chimpanzees care for their offspring’s young.

It was previously thought chimpanzees do not take care of their offspring’s young in the same way that humans do.

“”We learned for the first time that chimpanzees share a prototype of the role of grandmother, which is characteristic of humans,”” said a researcher from Kyoto University’s Primate Research Institute.

Professor Tetsuro Matsuzawa and associate professor Shinya Yamamoto have been in Bossou, Guinea, home to the wild chimpanzees, since December.

They saw a female chimpanzee, presumed to be about 55 years old, or more than 70 in human years, beckon to a 3-year-old youngster and they walked off in the forest. When they went to cross a road about four meters wide, the older chimpanzee carried the infant on her back, according to the researchers.

“”In Bossou, because the chimps are well nourished, they have extended life spans and undergo longer periods without giving birth. It is reasonable for experienced older chimps to take care of youngsters. Humans might have evolved through that kind of process,”” Matsuzawa said.