When an animal helps another animal, it usually gets something valuable in return. For a long time, many scientists thought that only people could act generously just because it feels good. However, a new study in Germany suggests that chimpanzees  also do good things for no real reason. And so do children who are as young as 18 months of age. Maybe it is because humans and chimpanzees share an ancestor  about 6 million years ago. People and chimpanzees appear to develop such features  without any other training, says Warneken, a scientist in Germany. Warneken and his partners worked on adult chimpanzees that live on an island in the African country of Uganda. They also worked with 18-month-old children in Germany. The researchers performed three experiments on the adult chimpanzees and two experiments on the kids. In the first animal experiment,a person tried to reach his arm into a cage to get a stick,but he couldn't reach it. A chimpanzee was in the cage,and it could reach the stick if it wanted to. Thirty-six chimpanzees took part in this experiment one by one, and no chimpanzee saw what the other chimpanzees had done. Even though the animals hadn't met the person before, they usually took the stick and gave it to the person. What's more, they did this whether or not the person offered them bananas as a reward. In a similar experiment, 36 children acted in a similar way. They helped the person reach the stick, whether or not they were offered toys for their help. Researchers did other experiments on chimpanzees and babies. No rewards were offered in either experiment. And still, both the chimpanzees and children went out of their way to help. Still, the new study is different from earlier findings. Researchers have found that chimpanzees don't give rewards of food to other chimpanzees, even if it costs them nothing to be generous. Warneken and his partners worked with   _  .
young chimpanzee that live on an island 18-month-old children who live in Germany kids who are living with adult chimpanzees adult chimpanzees that live on the African mountain