Ok, here's a mystery of science for you: how did lemurs get to
Madagascar? From genetic analysis, we know their ancestors traversed
the 250 miles separating the island from mainland Africa between 50 and
60 million years ago, but how? Land bridge? Swimming (that's a long
paddle)? How about rafts.
It's actually an old idea, one that had been shelved because present
day ocean currents in the Indian Ocean would blow any seafaring
primates back to the continent. But a new look at ancient currents
suggests conditions were right for impromptu voyages between 56 and 34
million years ago. The study was published in a recent issue of Nature (though I first read about it at Laelaps).
Now, these wouldn't have been pleasant journeys — most of the 'rafts'
were just floating pieces of vegetation cast out to sea during a
tropical storm along with their unfortunate passengers. Even in the
best of times, transit aboard one of these rickety vessels would've
been a couple of weeks, and the vast majority of animals likely never
Still, there's another reason to believe the rafting idea. Other groups
of mammals on Madagascar today like rodents, carnivorans, and so on
appear to have arrived over the course of tens of millions of years. If
they used a land bridge, you'd expect the whole menagerie to arrive more or less at the same time.
Image: Tambako on Flickr