In the light of Wise and Croxton‘s proposal that rafting on floating vegetation played a major role in post-Flood biogeographic dispersal, this advance Nature publication caught my eye. In 1940, George Gaylord Simpson proposed that the ancestors of the present-day mammals of Madagascar had rafted to the island from the African mainland. But there was a problem with his idea: the observed ocean currents didn’t fit the theory. Others argued that the mammals got there across a long-vanished land bridge – but that didn’t explain why only smaller mammals (e.g. lemurs, tenrecs, rodents) apparently made the journey.
New modelling work reported by Ali and Huber (2010) may have solved the problem. Their study suggests that during the Palaeogene (when the mammals in question were arriving) the ocean currents would have been in just the right position to allow rafting from the mainland. That’s because Africa and Madagascar were 15 degrees further south and the Mozambique Channel separating them was in a different ocean gyre than today. As plate tectonics moved Africa and Madagascar northwards, the current system evolved towards its present configuration and the delivery of species eventually stopped. So Ali and Huber conclude that Simpson was probably right all along.
Ali J. R. and Huber M. 2010. Mammalian biodiversity on Madagascar controlled by ocean currents. Nature advance online publication, 20 January 2010. doi:10.1038/nature08706.
Wise K. P. and Croxton M. 2003. Rafting: a post-Flood biogeographic dispersal mechanism, in: Ivey R. L., Jr. (editor), Proceedings of the Fifth International Conference on Creationism, Creation Science Fellowship, Pittsburgh, pp.465-477.