A new study suggests that the genetic diversity of head lice mirrors the history of human migration and colonization in the Americas. Marina Ascunce and her colleagues at the United States Department of Agriculture report these findings in a study published in the open-access journal PLOS ONE.
Head lice are wingless parasites that survive by feeding on human blood. They have coexisted with humans for thousands of years, and studying lice can provide insights into human evolution.
In this study, researchers analyzed the genetic variation in 274 head lice specimens from 25 different regions around the world. The analysis revealed the existence of two distinct clusters of lice that rarely interbred.
Cluster I was found worldwide, while Cluster II was found primarily in Europe and the Americas. The only lice that had ancestry from both clusters were found in the Americas. This suggests that these lice are a result of interbreeding between lice descended from populations that arrived during the first wave of human migration across the Bering Strait and lice that descended from European lice brought over during colonization.
The researchers also found a genetic relationship between lice in Asia and Central America. This supports the theory that people from East Asia migrated to North America and became the first Native Americans. These individuals then migrated south into Central America, where modern lice populations still retain genetic traits from their distant Asian ancestors.
The patterns observed in this study align with existing ideas about human migration and provide further insight into the evolution of lice. The researchers note that they selected genetic markers that evolve quickly and are best suited for analyzing recent events. Future studies that use markers that have changed more slowly could uncover information about more ancient events.
Additionally, the methods developed for this study could be utilized to study other host-parasite systems. The authors highlight that head lice are not just annoying parasites, but also serve as indicators of human evolution. Their reliance on human blood has resulted in a long co-evolutionary history that provides valuable information about our own species.
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1. Source: Coherent Market Insights, Public sources, Desk research
2. We have leveraged AI tools to mine information and compile it
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