Head lice reveal a new chapter in human history
A recent global genetic study of head lice has shed light on the complex history of human migration, revealing that lice arrived in the Americas twice – once during the initial wave of human migration across the Bering Strait and again during the European colonization.
The study, published in the open-access journal PLOS ONE, was led by Marina Ascunce, currently at the United States Department of Agriculture’s Agricultural Research Service (USDA-ARS), and her colleagues. The researchers analyzed the genetic diversity of 274 human lice from 25 geographic sites around the world.
The genetic analysis of louse DNA unveiled two distinct clusters of lice that rarely interbred. Cluster I had a worldwide distribution, while Cluster II was found in Europe and the Americas. The only lice with ancestry from both clusters were found in the Americas, suggesting a mixture between lice descended from populations that arrived with the First People and those descended from European lice brought over during the colonization of the Americas.
The researchers also identified a genetic relationship between lice in Asia and Central America, corroborating the theory that people from East Asia migrated to North America and became the first Native Americans. This genetic connection provides further evidence of the migration patterns of early humans.
The study’s findings support existing ideas about human migration and provide additional knowledge about how lice have evolved. The researchers noted that future studies using genetic markers that evolve more slowly could shed light on more ancient events, while the methods developed for this work could guide the development of new analyses to study other host-parasite systems.
The authors emphasized that human lice are more than just annoying parasites – they are “satellites” of human evolution. As human lice feed on human blood, they have co-evolved with humans over millions of years, providing a unique insight into human history.
The study, titled “Nuclear genetic diversity of head lice sheds light on human dispersal around the world,” was published on November 8, 2023, in PLOS ONE.
This new study adds a fascinating new chapter to our understanding of human history, providing important insights into the complex and intertwined history of humans and lice.