The ring-tailed lemurs belong to the so-called 'prosimians'. Most species of prosimians have developed on the island of Madagascar, but there are also prosimians on the African mainland and in Asia. Until a few years ago, ring-tailed lemurs were the least endangered species of prosimians on Madagascar. Meanwhile, biologists are worried about their future. The population growth on Madagascar is very large, so all nature reserves there are under increasing pressure.