To this day, little is known about social structures or the reproduction of lemurs, but it is certain that lemurs live in a fixed area or territory. There is an interesting theory about the distribution of animals on the island that has to do with the origin of Madagascar. About 150 million years ago, a large part of the mainland is said to have been broken off. This became Madagascar. The natural enemies of the lemurs as for example the lions remained on the mainland, which led to a stronger spread of the semi-monkeys. The forest spirits of Madagascar are to be found in spite of the smaller habitat however still in large number in the forest, above all the more widespread types like the Katta, the Mausmaki or the Fettschwanzmaki.