Of Lice and Men: The Molecular Evolution of Human Lice

Lice are ubiquitous parasites, as they infest practically all mammals and even birds. However, while most mammals are parasitized by just one type of lice, humans are blessed with three different kinds of lice, informally known as the head louse, the body louse, and the pubic louse. Moreover, these lice are all obligate parasites of humans, meaning that they cannot live on other animals, and they cannot exist for more than ~24 hours away from the human body without feeding. Thus, these human lice are intimately associated with humans, and the spread of human lice around the world reflects human migrations, so by studying genetic variation in lice we might learn more about such human migrations. However, it turns out that human lice are potentially even more fascinating in that the differences among the three types of human lice probably reflect important developments during human evolution. During my talk I will discuss why this is likely to be the case, and what we can learn about these important developments by studying the molecular evolution of human lice.