Host specific parasites, such as lice, occasionally undergo long-term coevolution with their hosts. In these coevolving assemblages it is often possible to infer the evolutionary history of the host simply by observing the phylogeny of the parasite. For example, human lice diverged from chimp lice approximately 5-6 million years ago. Similarly, human lice show the telltale signs of a rapid population expansion out-of-Africa 100,000 years ago. More importantly, these host specific parasites might be able to inform us about portions of their host’s evolutionary history that is obscured in host DNA. Herein I present recent data from the study of primates and their ectoparasitic sucking lice, which shed light on events such as the origin of modernization in humans as well as recent events such as the peopling of the Americas.