What's A Lemur?

Ask the person next to you what a lemur is and she or he may not even know it's an animal. Someone more acquainted with the tree-hopping, furry creatures might guess they're related to squirrels or cats. But the truth is, lemurs are more closely related to you and me.

Lemurs are primates, a subgrouping of mammals (an "Order" in biological taxonomic language) that includes monkeys, apes and humans. There are approximately 32 different types (or species) of lemurs in existence today, all of which are endemic to (meaning found only in) Madagascar; a single island country off the southeast coast of Africa.

In order to understand the differences between lemurs and other primates, it helps to envision primates as consisting of two major groups (or "suborders"): anthropoids and prosimians. Monkeys, apes and humans are anthropoids. Lemurs are prosimians. Other prosimians include galagoes (sometime called bushbabies), who live in Africa, and lorises (who live in India,Sri Lanka, and southeast Asia) and pottos, who live in Africa.

There's another primate, the tarsier (found in Borneo and the Philippines) whose exact place among the primates is still undecided. Some primatologists place them in the prosimians; others place them among the anthropoids. Tarsiers live in many types of forests and are nocturnal, specialized jumpers that feed on insects and small vertebrates, and live in small family groups.

Unlike all other primates, prosimians have long snouts, moist noses and rely on their sense of smell to determine what is safe to eat and to distinguish between individuals in their social groups. They also have tactile vibrisa (like the "whiskers" on a cat), and they can move their ears (like cats and horses). Like other primates, prosimians groom themselves and their acquaintances, but because prosimians can't use their fingers in the same way, they use their teeth as a comb.

In prosimian species, females play the dominant role. They get the best food choices in the wild, defend the group and choose with whom they mate.

The ancestors of lemurs and lorises evolved before the ancestors of monkeys, apes and humans. The first lemur-like primate appears in the fossil record about 55 million years ago, the first anthropoid about 45 million years ago, the first monkey about 35 million years ago, the first ape about 22.5 million years ago, and the first human about 5-6 million years ago.

Before the appearance of anthropoids, prosimians were quite prevalent. Their fossils have been discovered in all corners of the world, including Europe, Asia, Egypt and even in the northwestern United States. While Madagascar broke away from Africa more than 120 million years ago, it's puzzling to scientists that lemurs evolved only 55 million years ago. One of the theories of how lemurs got to Madagascar is that they rafted there on clumps of vegetation. (This theory is talked about in the movie In The Wild: Lemurs, shown in class.)

Once monkeys and apes appeared in Africa and Asia, day-time active prosimians were out-competed and disappeared. Only night-time active prosimians (lorises, galagoes, pottos) occur outside of Madagascar because there are no nocturnal monkeys or apes in those regions.

Since humans arrived on the island of Madagascar, approximately 1,200 to 1,500 years ago, 16 species of lemurs have become extinct, due to habitat destruction and hunting by humans. The largest of the extinct lemurs was known as Archaeoindris and was about the size of a modern male gorilla. Some of these extinct lemurs were ground dwelling while others lived in the trees and moved very much like sloths. Generally, those species now extinct were among the largest and most slow moving of all lemurs.

Lemurs tend to be omnivorous, eating fruits, gums, insects, and leaves. They have a well-developed sense of smell with a moist rhinarium (or nose) and scent glands. They also have a tapetum, a layer in the eye's retina that reflects light and enhances night vision. Lemurs range in size from about 40 grams for the mouse lemur to 8 kilograms for the indri, the largest of living lemurs. The indriis, along with sifakas, have extremely long legs and are capable of spectacular leaps of up to 10 meters between vertical supports.

In 1987, World Wildlife International declared that the lemurs are the most gravely endangered group of primates in the world.