During that time, Ada and Aduma have broken Marta Llanes's television and computer keyboard, chewed her telephone to pieces and ruined much of her furniture.

She has forgiven them every transgression as she said it is hard to stay angry at a baby chimpanzee when it clambers up your leg and into your arms and plants a kiss on your cheek in a plea for forgiveness.

While zoos in other countries may have special facilities for raising baby animals, in Cuba the job falls to Ms Llanes, 62, who has cared for 10 baby chimps in her central Havana apartment since she started working at the city zoo in 1983.

It is hard work that requires watching the animals nearly 17 hours a day until they are returned to the zoo after their first birthday.

"I try to be the mother chimpanzee," she said. "If they say 'hu', I say 'hu'.If they want me to drop to the floor, I drop to the floor. The only thing I can't do is swing. I used to do it, but I can't anymore, but they have to be taught to swing. They have to be taught everything."

She leaves her home a few hours each week when another zoologist delivers milk, fruit and cleaning products, and cares for the animals while she takes a break.

Meanwhile, her apartment looks like any that is home to two infants, albeit infants able to scramble up chairs, tables and virtually any other object with already-strong arms and legs, and feet with opposable "thumbs".

The floor is covered with toys, all sharp objects have been hidden away and the electric sockets covered to prevent a dangerous accidental shock.

Ada, the female, is 13 months old, and the male Anuma is 15 months. Both wear nappies.

The chimpanzee, an endangered species, separated from humans on the evolutionary tree about seven million years ago and shares some 90% of our DNA.

Chimps are known for their intelligence and use of basic tools. They live half a century in the wild and even longer in captivity.

Ms Llanes, who has an adult daughter, said it can be difficult to get female chimps to care for their offspring in captivity, and she has been happy to step in.

She is raising the baby chimps because their mothers at the zoo are too young and did not learn how to feed or care for them properly.

"I have to be at home with them 24 hours a day," said Ms Llanes, who rises at 5am and often watches the chimps until 10pm, with an occasional break during a simultaneous nap.

She lives in a fifth-floor apartment in a building with dozens of residents, virtually all of whom say the baby chimps are good neighbours.

"They don't bother anyone," said Cari Dib, a 65-year-old housewife. "Plus, they're adorable."