2023-12-24 05:00:00
A scientist born in Plaza Huincul, Neuquén, biologist Ariel Toloza, participated in the first study that detailed the map of lice migrations on the heads of human beings. around the world for thousands of years.
With colleagues from the United States and Mexico, he reconstructed the routes and discovered that there were two migratory streams of entry of lice into America. The first occurred 30 thousand years ago and the other following the arrival of Christopher Columbus.
The results of the research were recently published in the scientific journal PLOS ONE, and one of the co-authors was Toloza, a Conicet researcher at the Pest and Insecticide Research Center, which is a collaborator of the World Health Organization. He worked with scientists from the University of Florida, in the United States, and the National Autonomous University of Mexico.
Head lice are small parasitic insects with 6 legs and no wings. They measure between 2 and 4 millimeters. They live exclusively on the heads of humans and feed on blood. They feed 4 to 5 times a day and can only survive 24 hours outside of humans’ heads.
Before starting, the researchers took into account that since there was this intimate relationship between the parasite and the human host, there was co-evolution. Therefore, they knew that research might shed light on aspects of evolution that are difficult to interpret using other biological evidence.
They performed genetic analyzes on 274 human lice from 25 geographic sites in 19 countries. such as Nepal, Thailand, Cambodia, Croatia, Holland, Spain, United States, Honduras, Mexico, Peru, Argentina and others. In addition, this information was crossed with archaeological and biological data related to human migratory events, the life cycle of lice, their differential levels of parasitism and other variables to simulate statistically probable scenarios.
In dialogue with Rio Negro NewspaperToloza said that it might be inferred that “lice have followed humans, in their migratory movements, throughout the world for a long time.
Lice then arrived in America on two occasions or migratory waves. One that occurred approximately 30 thousand years ago, when the first A wise man “They arrived in America, coming from East Asia, through the Bering Strait,” he said.
The second entry occurred more recently: “It was when the first Europeans arrived in America,” following 1492, in the period following Christopher Columbus, he noted. “They have shared life stories: lice have accompanied humans since the beginning of our existence,” he highlighted.
How was the study done
If humans moved through this or that region, it is “recorded” in the DNA of their parasites, forming a “genetic fingerprint,” which contains the information of those migrations, he explained. Through tools of molecular biology and genetics, “scientists can estimate where humans have walked throughout history,” Toloza clarified.
“It is important to note that the lice analyzed are current – collected in schools and centers and not ancient or fossils. The DNA was extracted from that material and by using markers called microsatellites and mitochondrial DNA sequences, different genetic patterns might be inferred,” he noted.
The analyzes were done at the University of Florida facilities, located in the city of Gainesville. The study revealed the presence of two different groups of lice. “They were genetically isolated for a long time and we found hybrids almost exclusively in America, reflecting the colonization of America in two large waves,” he commented.
The first of them, detected in lice from Honduras and Mexico, with “genetic fingerprints”, coming from the first groups of aborigines that arrived in America. The second was detected in lice from the United States and Argentina. It is an indicator of the arrival of Europeans with Columbus.
Does taking a selfie increase the risk of getting lice?
Lice have been in contact with the ancestors of humans for more than 2 million years. “Many fine combs designed in wood and ivory have been found in archaeological sites that indicate that control measures were taken to eliminate these parasitic insects,” said Conicet biologist Ariel Toloza.
This “coexistence” with lice has been accompanied by the circulation of myths. For example, one of them says that they “jump or fly” from one head to another. However, this is false, because lice do not have wings or jumping legs, as is the case with fleas.
Lice can only walk and are very fast on hair. That’s why they take the opportunity to pass by when their heads are together. If a person with lice takes a “selfie” photo with another person, it is very likely that they will become infected due to the proximity, but not due to the supposed jump of the lice.
Another myth is that bathing in the pool, especially during childhood during summer camps, is a situation that increases the risk of having lice. That’s not true either. These insects are very attached to the hair while the person gets into the pool. They can hold their breath for more than eight hours. They don’t like water to swim in.
Some families put vinegar in the hair of people with lice. They believe it is a method to combat them. But it is known that alcohol vinegar used as a condiment in food does not kill or repel lice.
Toloza and colleagues from CIPEIN del Conicet have created a page in which more myths and appropriate treatments are mentioned (www.sobrepiojos.com.ar).
1703394357
#lice #migrated #humans #world
