As we discuss primate genomes, I found an interesting article about a recent genetics study. In this study which was published in the American Journal of Physical Anthropology this past December, genetic and morphological data was collected from two howler monkey species who differ in everything from behavior to the number of chromosomes they possess. The study also collected data from individuals in an area in which the two species interbred. The results of the study found that hybrid monkeys that shared most, but not all of their genome with one species could not be physically distinguished from the pure individuals of that species. This is especially interesting because it can be related back to human ancestry. Anthropologists heavily rely on the human fossil record in order to infer hybridization as it relates to human evolution, but the fossil record can lead to different conclusions about hybridization than the assessment of molecular data. The study implies that the extent to which early humans interbred could have been drastically underestimated.