Book Review: The Monkeys Voyage (Washington Post)
In June 2000, Alan de Queiroz became curious about an enormous, ragged-looking garter snake that lived on the tip of Baja California. Like many other biologists of his generation, de Quieroz had been taught that species traveled the Earth to new habitats on slowly drifting continents. This snake had relatives on the other side of the Sea of Cortéz on Mexico’s mainland, and de Queiroz assumed that this population ended up on Baja 4 to 8 million years ago, when the peninsula split from the mainland.
But using a new method based on genetic sequencing to estimate when the two populations split, he found that it had occurred in the past few hundred thousand years. In other words, one or more pioneering garter snakes had probably floated across 120 miles of open ocean.
As de Queiroz prepared to write up the surprising results of his snake study, he discovered that the reptile was not an outlier. Biologists were finding that even after continents drifted apart, plants and animals somehow hopped between them. “Obviously, the continents had moved — nobody was claiming that the theory of plate tectonics was wrong — and obviously, they had carried species with them,” he writes, “but somehow, these facts did not explain nearly as much about the modern living world as we had thought.” Chance ocean crossings did.