ARI SHAPIRO, host:
The island of Madagascar off the east coast of Africa is home to a bizarre menagerie of animals that live nowhere else. Biologists believe these creatures arrived millions of years ago from the African mainland, but no one really knows how they made the trip. Now, scientists are proposing that they floated there.
NPR's Christopher Joyce has this story on the animal arks of Madagascar.
(Soundbite of lemur)
CHRISTOPHER JOYCE: That's a lemur. Madagascar has some 70 kinds of this tree-dwelling primate, from the one-ounce pygmy mouse lemur to the eerily vocal indri, which looks like a teddy bear and sounds like an air horn.
Lemurs, chameleons, a mongoose-like mammal called a fossa these strange creatures look like they were left behind by Noah's ark. Scientists believe they got to Madagascar from Africa millions of years ago and evolved in their own peculiar ways. But how did they cross 300 miles of ocean that separates the continent and the island?
Seventy years ago, one biologist noticed that Madagascar's animals are small, so their ancestors probably were small too and could have rafted over as refugees on floating mats of vegetation or tree limbs.
Professor MATTHEW HUBER (Earth Science, Purdue University): But there was a big problem with the idea.
JOYCE: That's Matthew Huber, an Earth scientist from Purdue University.
Prof. HUBER: The ocean currents go the other way.
JOYCE: This was such a puzzle that some biologists concluded that the sea level must have been lower at some point, and the animals just walked over.
Huber says no way. The undersea geology isn't right for that. Besides, big animals, say lions and elephants, would have walked to Madagascar on the land bridge as well.
So, Huber and a scientific colleague in Hong Kong asked themselves, maybe the ocean currents were different millions of years ago. Huber built a computer model that simulated the Earth oceans, continents, even vegetation as it would have been 60 million years ago. And they found...
Prof. HUBER: As far as Madagascar is concerned, the currents went the other way. They go from Africa towards Madagascar in the past. And the reason is actually pretty straightforward the locations of the continents were different.
JOYCE: Africa and Madagascar sat about a thousand miles farther south back then. So, Huber writes in the journal Nature, a whole menagerie could have floated to Madagascar.
Not like it would have been much fun like a Hollywood movie. Huber says the currents were just right for the three-week voyage only a few times every century.
(Soundbite of lemurs)
JOYCE: So, you to be a very lucky lemur to get to Madagascar.
Christopher Joyce, NPR News.