Scientists have found four different lineages of Demodex folliculorum (a type of mite) that belong to several regions of the world, after they studied these microscopic animals that inhabits our faces. It appears that people from Africa, Europe, Asia and South America have all different mites with distinctive genetic codes. The research was published online on Tuesday by the Proceedings of the National Academy of Sciences in the United States of America.

According to the research, these microscopic creatures of the genus Demodex, which are situated in mammals’ hair follicles and usually cause no harm, would demonstrate how human species have evolved and migrated through history. Scientists analyzed among 241 mites sequences, taken from 70 human hosts from various backgrounds. Results showed that people had ancestries from all continents.

These microscopic creatures, known as Demodex folliculorum, would demonstrate how human species have evolved and migrated through history. Credit:

After analyzing the DNA of mites, they identified four distinct groups of them, as the paper states, hosts with different regional ancestries harbor distinct lineages of mites even when they moved to new geographic regions.

Dr. Michelle Trautwein, academy curator of entomology and senior author of the new findings, wrote in the publication that improving our understanding of human follicle mites, promises to shed light on human evolution and to provide important contextual information for their role in human health.

“We discovered that people from different parts of the world host different mite lineages. The continent where a person’s ancestry originated tended to predict the types of mites on their faces. We found that mite lineages can persist in hosts for generations. Even if you move to a faraway region, your mites stick with you,” Dr. Michelle Trautwein explained.

An interesting thing that researchers found is that the last common ancestor of the four mites found, lived more than 3 million years ago, which means they coexisted before modern humans. It is recognized by the scientific community that human beings evolved earlier in Africa, the distribution of mite sequences affirm that premise. It seems the most different mites were found in people of African descent, they had all the four clades.

Results would appear to show that some mite populations are better able to survive and reproduce on hosts from certain geographic regions, the researchers wrote. That means, when people move from their geographic region some mites can’t survive or adapt to the new conditions. Michael Palopoli, an evolutionary biologist at Bowdoin College in Brunswick Maine who led the study, explained when people moved from Africa to Asia or Europe some individual lineages were lost.

“Another exciting mite revelation from our work is that mites aren’t shared easily. Mites are not casually transferred to passersby on the street. We seem to share mites primarily with our family, so it likely takes very close physical contact to transmit mites,” Dr. Michelle Trautwein declared.

The new findings open the door to an innovative perspective that could help studying human evolution, which is a subject that has been analyzed by thousands of scientists since Charles Darwin published the Origin of Species, on November 24, 1859. Dr. Michelle Trautwein will conduct a new investigation that will take samples of mites alongside citizen scientists in homes from all around the world, in order to explore the relation between the microscopic creatures that are in our bodies and our homes.

Source: Proceedings of the National Academy of Sciences of the United States of America