Gene Sharing Between Neanderthals and Humans

Human evolution is the evolutionary process behind the emergence of anatomically modern humans, beginning with the evolutionary history of primates – in particular genus Homo – and leading to the emergence of Homo sapiens as a distinct species of the hominid family, the great apes. Human evolution has always been depicted as a straight line and a simple process.

Due to the discovery of genetic material from extinct subspecies and the next level generation sequencing, the entire process has become slightly complex. As per a recent study that has come forward, new details concerning the important role played by viruses have come up, specifically the viral interactions between modern humans and Neanderthals. It is very simple to understand that when interaction took place between modern humans and Neanderthals, the share of pathogens must have taken place. Upon interbreeding with each other, they would have passed on certain genetic adaptations as well. The modern human beings moved out of Africa and into Eurasia about 70,000 years ago. It is a well established fact that the Eurasian environment shaped Neanderthals' evolution, including the development of adaptations to viruses and other pathogens that were present there but not in Africa. Few of the Neanderthals possessed adaptive mutations therefore they could easily pass these pathogens to the modern humans. The new study has been authored by Enard and Dmitri Petrov, the Michelle and Kevin Douglas, Professor of Biology at Stanford University. They have been using bioinformatics tools to study global patterns of evolution across tens of thousands of years. They have been researching on the impact of viruses on evolution of humans since many years. In 2016, they highlighted that about 1/3 rd of the protein adaptations were driven by a response to infectious viruses. This was because humans split from other great apes. The researchers indulged in annotating about 4000- 25000 genes in the human genome that are known to interact with the pathogens. Such genes become the focus of study and research because these are widely involved in adaptation against infectious disease as compared to those genes that don't have anything to do with viruses. As the next step they then looked at whether there was an enrichment of stretches of Neanderthal DNA in those 4,000 genes. Another important point that came forward during the research was that many Neanderthal sequences get lost in modern humans. Some other sequences stayed and appeared to have quickly increased to high frequencies at the time of contact. This behavior is highly indicative of their selective benefits at that time. The research answered many questions such as “Why have we maintained stretches of Neanderthal DNA in our own genomes”? The presence of these stretches provides us with some protection against pathogens as we moved into new environments. Such researches are extremely beneficial as they help and bring to the forefront new clues about ancient disease outbreaks. These researches help in suggesting better ways to monitor diseases in the near future.

By: Anuja Arora

Content: https://www.sciencedaily.com/releases/2018/10/181004112547.htm