Parasitic lice as markers of modern and archaic human introgression

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The pattern of early human evolution is a compelling topic for study. Fossil and genetic data provide deep insights into human history. Yet there are many important questions left unanswered. Recent research has found evidence of Neanderthal genes in modern humans. Scientists have shown that this shared DNA resulted from interbreeding during periods where modern humans and Neanderthals overlapped in time and space. What scientists have not been able to do is determine are the specific times, places and social context of this interbreeding. The human genetic data does not allow us to differentiate brief events from prolonged interbreeding. However, the distinct populations of lice that live on different human populations should remain distinct unless those human populations have prolonged and intimate contact. Therefore, this research will use louse genes to determine when, where, and for what duration these humans were in close contact in the distant past. The researchers will collect lice from populations in northern Africa, and the Middle East where human introgression with Neanderthals is thought to have first occurred. Genetic data from these lice will be collected and examined to explore patterns of human evolution. This project will train undergraduate students, graduate students, and a postdoctoral researcher how to effectively communicate research findings to broad audiences. The research team will also help museums promote scientific literacy in Middle School and High School students. Patterns of DNA variation in the Human Louse (Pedicularis humanus) confirm interactions between now-extinct humans such as Neanderthal and Modern humans. Further, there is even greater evidence of interbreeding between the lice of these two hosts than we see in the hosts themselves. Increased sampling of genomes across a broad geographic range of Louse samples from 90 key geographic populations will allow improved modeling of the location and nature of interactions between Neanderthal and Modern humans. Coalescent simulations will be generated based on the observed characteristics of roughly 10,000 P. humanus genes in 90 populations using the University of Florida's high-performance computer cluster (HiPerGator). Approximate Bayesian Computation will be used to determine what model of human behavior across time best fits the data that is generated.