Global genetic studies of lice suggest that they arrived in the New World twice, using humans as hosts.
A new analysis of the genetic diversity of lice suggests that they arrived in the Americas twice. The first time was during the first wave of human migration across the Bering Strait, and the second time was during European colonization. Marina Ascans, now at the USDA-ARS, and colleagues report these findings in a new study published November 8 in an open access journal. Pro Swan.
Lice as an indicator of human evolution
Human lice are wingless blood-sucking parasites that live their entire lives on their hosts.It is one of the oldest known parasites living in humans; seed They have co-evolved for thousands of years. Because of this close relationship, studying lice may also provide clues to how humans evolved. In the new study, researchers analyzed genetic variation in 274 human lice from 25 geographic locations around the world.
Genetic clusters reveal migration patterns
Genetic analysis based on lice DNA They revealed the existence of two distinct clusters of lice that rarely interbreed. Cluster I was distributed worldwide, while Cluster II was found in Europe and the Americas. The only louse with ancestry from both clusters is found in the Americas. This distinct group is thought to be the result of a mixture of lice that are descendants of populations that arrived with first people and lice that are descendants of European lice that were introduced during the colonization of the Americas. Masu.
Relationship between Asian lice and Central American lice
Researchers also identified genetic relationships between lice in Asia and Central America. This supports the idea that East Asian people migrated to North America and became the first Native Americans. These people then spread south to Central America, where modern louse populations today still retain genetic characteristics from their distant Asian ancestors.
Future research and conclusions
The patterns observed in the new study support existing ideas about human migration and provide additional knowledge about how lice evolved. The researchers note that they selected genetic markers that evolve rapidly and are best suited to recent events. Therefore, future studies using markers that changed more slowly may shed light on more ancient events. Furthermore, the methods developed for this study may guide the development of new assays to study other host-parasite systems.
The authors go on to say, “Human lice are not only nuisance human parasites, they are also our evolutionary ‘satellites.” Human lice feed on human blood, so if humans are to survive, humans must survive. necessary, resulting in a long history of coevolution spanning millions of years.”
Reference: “Nuclear genetic diversity in head lice sheds light on human dispersal around the world” by Marina S. Ascans, Ariel C. Toloza, Angelica Gonzalez-Oliver, and David L. Reed, 2023 November 8th, Pro Swan.
DOI: 10.1371/journal.pone.0293409