Louse genes may shed light on human migration history – study
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Lice “haunted” human ancestors for at least 25 million years. These parasites evolved with them and adapted to different environmental conditions.
A group of scientists from the USA, Argentina and Mexico assures that it is with the help of genetic analysis of lice that it is possible to learn more about the movement of the human species around the world.
The corresponding study was published in the scientific journal PLOS One, reports The New York Times.
Lice usually live on people’s heads. They pierce the skin and drink blood. Lice do not survive far from humans, so they constantly jump from one to another.
| Louse up close. Photo: PMARACENA/Depositphotos |
Lice fossils are very rare. However, with the help of their DNA, scientists have learned to build entire family trees, revealing the closeness of different species.
In their study, an international group of scientists found that some lice in America are hybrids of those that “lived” on Native Americans and colonizers from Europe.
“We humans don’t live in a bubble. Lice are part of our lives and our history.” – says co-author of the study Marina Askunse.
The impetus for this study was a past work in which scientists compared human lice from different parts of the world. They studied the genetic material (mitochondrial DNA) that is passed down only from females. Then it turned out that many lice are divided into two lines.
Scientists have assumed that the “split” between them occurred when people moved out of Africa. There they picked up the lice of Neanderthals or other extinct groups of people.
In the new study, scientists analyzed the DNA of 274 lice collected from people from 25 locations around the world, including Honduras, France, Rwanda and Mongolia.
Scientists discovered two geographical clusters of lice. One was present in Africa, Asia and part of America. The other is in Europe, USA, Mexico and Argentina. Among these two clusters, scientists singled out 33 hybrids, 25 of which lived in America.
The researchers saw a close genetic link between lice from Honduras and Mongolia. They believe that this affinity is a sign that Asians, who first appeared in America about 23,000 years ago, brought lice with them.
A large number of hybrids in America, according to scientists, arose precisely because of the colonizers. When they sailed from Europe to the New World, they brought lice with them. When these parasites spread, they ended up on the heads of people already infected with another cluster.
However, if these hybrids are really related to colonialism, they are rare. Scientists assume that it is a matter of a certain barrier for crossing. For example, two groups of lice were isolated from each other for a long time, so they acquired incompatible mutations.
According to Marina Askune, this study only looked at 16 small sections of lice DNA. However, in the future, scientists plan to study the entire genome.
In particular, they will try to understand how human lice evolved the ability to move from the head to the body, and why only body lice carry germs that can cause diseases such as typhus.
Scientists also hope to determine exactly how the ancestors caught lice.
“The genetic information we see in modern human lice can still tell us about our human past,” – says Askunse.
We will remind you that earlier we wrote that earthworms and Russia make approximately the same contribution to the world grain harvest.
Read also: Lived before dinosaurs: scientists discovered the oldest creature on Earth
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