Chimpanzees live together in larger groups of up to 150 individuals, headed by an alpha male. Just like humans, their hands have thumbs they can oppose to other digits. Therefore, they are able to grab things carefully. They use branches as tools to search a termite hill for food for example. Young chimps learn how to make and use such tools from their parents. They mainly have a vegetarian diet, but occasionally eat meat as well. Chimpanzees mostly run on all fours. Short distances can also be covered half-standing on their legs. Every four to six years, a chimp mother gives birth to an infant that will be raised by her for the next ten years. Chimpanzees have a life expectancy of up to 60 years.