Mammals Evolve Faster in the Tropics, Confounding Scientists

In the heat and humidity of the tropics you might expect that mammals take it slow and easy--but on the genetic level, they're accelerating past their mammalian relations that live in more temperate zones. A new study has discovered that tropical mammals are accumulating mutations more quickly and are therefore evolving faster, in a finding that could help account for the phenomenal biodiversity of the rainforests. But the study's unexpected results have posed a puzzle for biologists.