Lemur

A Madagascar-only group

Lemurs are an extraordinary case of island evolutionary radiation — over 100 species, all descended from a small population of ancestral primates that arrived on Madagascar approximately 60 million years ago, possibly by floating on storm-tossen vegetation rafts from Africa.

In the 88 million years since Madagascar separated from Africa, lemurs evolved in isolation, diversifying into a remarkable range of forms — from mouse-lemurs (30 g, the smallest primates on Earth) to indri (9 kg, the largest living lemur).

Female-dominant societies

Many lemur species — including the iconic ringtailed lemur — are female-dominant, with females taking priority over males in feeding, mating, and group leadership. This is highly unusual for primates (humans, chimpanzees, gorillas, baboons all have male-dominant or roughly egalitarian structures).

The exact evolutionary cause is debated. Possible factors include the resource-poor Madagascar environment placing breeding females under more selection pressure, or the long isolation allowing alternative social structures to evolve.

Many species, all threatened

Lemurs include over 100 species, with scientific descriptions of new species continuing to add to the count. The major groups:

• True lemurs (genus Lemur, Eulemur) — including ringtailed, brown, mongoose lemurs.
• Sportive lemurs — small, nocturnal.
• Sifakas — large, leaping, white or black-and-white.
• Indri — the largest extant lemur, with a haunting song.
• Aye-aye — bizarre, with elongated middle finger for extracting grubs.
• Mouse lemurs — tiny, nocturnal.
• Dwarf lemurs — small, hibernate in winter.

90%+ of lemur species are threatened with extinction, the most-imperiled group of mammals on Earth. Madagascar has lost 80% of its forest cover; lemurs depend almost entirely on what remains.

Subfossil giants

Until only 1,000-2,000 years ago, Madagascar hosted giant lemurs that have since gone extinct:

• Megaladapis — a koala-like lemur the size of a gorilla.
• Pachylemur — an extra-large ringtailed lemur relative.
• Archaeoindris — possibly 200 kg, larger than any living lemur.

These extinctions correspond closely with human arrival on Madagascar (~1,000-2,000 years ago) — humans hunted them and modified their habitat.

A dance lemur

The sifaka (genus Propithecus) has a uniquely dramatic terrestrial gait — when it crosses open ground, it bounces sideways on its hind legs in a dance-like motion. The behavior went viral on the internet via documentary footage; sifakas became Madagascar’s most-photographed lemur.