Leslea’s research into enamel thickness in baboons suggests that such traits can evolve quite quickly since they are genetically controlled and show extreme variation within a single population. And if a trait like enamel thickness can evolve quickly in baboons, it seems likely that such traits could have evolved quickly in hominids like ramidus and anamensis as well — so 300,000 years may actually be plenty of time for the evolutionary transition between the two to have taken place.

Or maybe not. The jury is still awaiting further evidence on the question of whether ramidus and anamensis were a single lineage or separate ones. That evidence could come in many forms. Studies of modern primate genetics, like Leslea’s work on baboon teeth, are key. Such research helps us understand how an organism’s genes and environment are reflected in its phenotype — a phenotype which may be preserved in the fossil record as a tooth or bone. As Leslea puts it, “my overall goal is to better understand how genes have influenced anatomical variation so that when we go back and look at the fossil record, we can interpret changes in bony morphology with a more accurate understanding of what that’s reflecting at a genetic level. A fossil tooth is a snapshot of how the genome and environment are interacting with each other at one time in history — and that’s the kind of thing I’m really interested in.”