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Why is Neanderthal Genetic material Found in only Small amount in Genomes of Modern Humans?

The scientists estimated that these gene variations were able to persist in Neanderthals because Neanderthals had a much smaller population size than humans

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FILE - A model of an adult Neanderthal male head and shoulders by artist John Gurche on display in the Hall of Human Origins in the Smithsonian Museum of Natural History in Washington, D.C. VOA

New York, November 9, 2016: Neanderthal genetic material is found in only small amount in the genomes of modern humans because, after inter-breeding, natural selection removed large numbers of weakly deleterious Neanderthal gene variants, says a study.

Humans and Neanderthals inter-bred tens of thousands of years ago, but today, Neanderthal DNA makes up only one to four per cent of the genomes of modern non-African people.

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“For a while now we have known that humans and Neanderthals hybridised. Many Europeans and Asians – along with other non-African populations – are the descendants of those hybrids,” said Ivan Juric from the University of California, Davis in the US.

“Previous work has also shown that, following hybridisation, many Neanderthal gene variants were lost from the modern human population due to selection. We wanted to better understand the causes of this loss,” Juric noted.

To understand how modern humans lost their Neanderthal genetic material and how humans and Neanderthals remained distinct, the researchers developed a novel method for estimating the average strength of natural selection against Neanderthal genetic material.

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They found that natural selection removed many Neanderthal alleles from the genome that might have had mildly negative effects.

The scientists estimated that these gene variations were able to persist in Neanderthals because Neanderthals had a much smaller population size than humans.

Once transferred into the human genome, however, these alleles became subject to natural selection, which was more effective in the larger human populations and has removed these gene variants over time.

“Our results are compatible with a scenario where the Neanderthal genome accumulated many weakly deleterious variants, because selection was not effective in the small Neanderthal populations. Those variants entered the human population after hybridisation,” Juric said.

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“Once in the larger human population, those deleterious variants were slowly purged by natural selection,” Juric noted.

These findings, published in the journal PLOS Genetics, shed new light on the role of population size on losing or maintaining Neanderthal ancestry in humans. (IANS)

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Scientists Find New Ways of Tracking Objects by Combining DNA of Dust Particles

Clothing, medicine and other items in one’s environment all have genetic markers, or fingerprints, that provide clues to where they came from, according to scientists

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Scientists say they have new ways of tracking where clothing, medicines and other items are made, making it harder for unscrupulous businesses to sell items that don't work or violate laws. VOA

Clothing, medicine and other items in one’s environment all have genetic markers, or fingerprints, that provide clues to where they came from, according to scientists.

Researchers are analyzing the microorganisms in dust particles that land on surfaces and are using artificial intelligence to read and classify the unique genetic codes of the microbes that vary from place to place.

“It is the collection of bacteria, fungi, viruses, protozoa that are present in any environment,” said Jessica Green, microbial systems expert and co-founder of Phylagen, a company that is building a microbial map of the world. Phylagen is collecting dust from different places and turning it into data by studying the DNA of the microscopic organisms in the particles.

DNA, dust particles
This digitally colorized microscope image provided by the National Institute of Allergy and Infectious Diseases (NIAID) shows Staphylococcus aureus bacteria in yellow. Bacteria are part of the collection of microorganisms that tell scientists where an object has been. VOA

Exposing labor abuses

Phylagen says its findings will provide real world applications. The California-based company says one application involves companies that outsource the manufacturing of products, such as clothing.

According to Human Rights Watch, unauthorized subcontracting of facilities in the apparel industry occurs often, and it is in these places that some of the worse labor abuses happen.

Phylagen is digitizing the genome of different locations by working in more than 40 countries and sampling the dust in hundreds of factories. The goal is to create a database so the microbes on each product can be traced.

“We sample the DNA of the products, and then, we use machine learning algorithms to map what is on the product with the factory, and can therefore verify for brands that their goods are made by their trusted suppliers in factories where you have good labor conditions, good environmental conditions versus unauthorized facilities which can be really detrimental,” Green said.

Tracking diseases, ships

With a database of distinct microbial DNA, Green said other possible future uses could include predicting the outbreak of disease and helping law enforcement track the movement of ships, since shipping logs can be falsified. Even counterfeit medicines could be traced as the database of microbial information grows, she said.

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“We can sequence the DNA of seized counterfeit pills, cluster together pills that have similar microbial signatures and then use that to help both pharmaceutical companies and the government, the U.S. government, gain some intelligence about how many different sources of these manufacturing facilities are there,” Green said. (VOA)