The Chronicles of the Lemurs

Every lemur alive today, and every one that ever lived, traces back to a single event. The leading theory, built on molecular evidence, holds that one small primate ancestor reached Madagascar from Africa around fifty to sixty million years ago. It did not swim and it did not fly. It rafted, most likely clinging to a tangle of storm-torn vegetation, carried across the Mozambique Channel by currents that, at the time, ran differently than they do now.

Scientists call this kind of accidental sea crossing “sweepstake dispersal,” a name that captures both how unlikely it was and how much rode on the outcome. Madagascar has sat roughly where it sits today for some eighty-eight million years, close enough to Africa that the trip was possible, far enough that it happened only rarely. Other African mammal groups made similar crossings on their own timelines: the ancestors of Madagascar’s carnivores rafted over between eighteen and twenty-four million years ago, and its native rodents arrived on a separate crossing of their own.

One raft, one ancestor, fifty million years of evolution with no competition to answer to.

What made the lemurs’ story different is what happened after they landed. On the African mainland, early primates had to compete with monkeys, which eventually outcompeted and displaced most of their close relatives. Madagascar’s raft never carried a monkey. Cut off from that competition entirely, the lemurs’ descendants had the island, and every empty niche in it, to themselves.

Left alone with the whole island, lemurs evolved into forms that no longer exist anywhere. The subfossil record lists entire families now extinct: the Archaeolemuridae, the Palaeopropithecidae, and the Megaladapidae among them, alongside a giant aye-aye, Daubentonia robusta, twice the size of the strange nocturnal species that survives today.

Some of these lemurs were built for the ground rather than the canopy, heavy-bodied animals with nothing left in Madagascar’s forests today built quite like them. Their disappearance, in the relatively recent past, represents a complex and multifaceted narrative. It has its own dedicated chronicle already.

An entire branch of the family tree, gone, and still being pieced back together bone by bone.

Today’s lemurs are organized into five families, a classification that helps make sense of a diversity most visitors don’t expect from a single order of animals. The Indriidae are the largest living prosimians, a family that includes the indri and the leaping sifakas. The Lemuridae hold the “true” lemurs: ring-tailed lemurs, bamboo lemurs, and the ruffed lemurs among them. The Lepilemuridae are strictly nocturnal, quiet and rarely seen in daylight.

Then there is the Cheirogaleidae, a family of small nocturnal lemurs that includes the mouse lemurs, among them the smallest primates on Earth. And there is the Daubentoniidae, a family with exactly one living member: the aye-aye, an animal so unusual it uses one elongated, skeletal middle finger to tap on bark and fish out grubs hidden beneath it.

Five families, one order, and new species still being described every year.

New species are still being added to the list. What looks, at first glance, like a single well-documented animal often turns out, on closer genetic inspection, to be several.

Three reserves, three very different encounters. Andasibe, a combination of national park and community-managed forest, holds half a dozen lemur species, but it is known above all for the indri and its wailing, siren-like call that carries for over a kilometer through the canopy.

Ranomafana, a rainforest UNESCO site established in 1991, works differently. A typical walk there turns up three to five species out of the roughly dozen recorded in the park, among them the golden bamboo lemur, a species discovered here only in 1986 and found in just two places on Earth. Night walks along the road above the park entrance are, by most accounts, the easiest way to find nocturnal lemurs and chameleons together.

An indri’s call carrying a kilometer through rainforest, a bamboo lemur found nowhere else but here and one other valley on Earth.

Kirindy, a dry deciduous forest reserve, holds eight recorded lemur species, most of them nocturnal. Night-spotting walks here regularly turn up Madame Berthe’s mouse lemur, at roughly thirty grams the smallest primate in the world, alongside fork-marked lemurs and Coquerel’s giant dwarf lemurs.