The Important Role Played by Viruses in Human Evolution

Scientists have long pointed to the relationship between pathogens and evolution, but until very recently, they have been unable to pinpoint specific patterns which occur across different species. In a fascinating new study carried out by the Genetic Society of America, they have discovered (using big-data analysis) that viruses are responsible for an impressive 30 per cent of all protein adaptations since the human divergence with chimpanzees.

The study, published in the journal eLife and presented on 14^th July at The Allied Genetics Conference, showed that the adaptive patterns caused by viruses are strong and very clear. Never before have viruses been shown to have such a powerful effect on how human beings have adapted. The researchers found that adaptations occurred three times as frequently in proteins which interacted with viruses, as in other proteins.

Thanks to the study, scientists can now identify which parts of the cell have successfully defeated viruses in the past. The differences in protein shape and composition in response to these threats, could help scientists find new ways to battle the most powerful viral threats currently faced by human beings. Previous research had focused only on individual proteins which are directly involved in the immune response.

When the body is faced with a virus, proteins throughout the whole body react; not only those involved with immunity. The researchers discovered that as much adaptation takes place outside the immune system, as within it. Viruses have affected us in every respect, affecting all parts of our cells. Proteins make a host of important cellular functions possible, so an analysis of tweaks and differences can give scientists vital clues as to how to face future threats. When pandemics and epidemics occur, populations must either adapt or risk becoming extinct and it is hoped that the observable changes in protein will help scientists new ways to help the body adapt.

The study helps scientists answer important questions, such as why species which are very similar have evolved different ways of fulfilling the same cellular function, such as cell membrane creation or DNA duplication. Scientists previously had no clue as to what evolutionary forces had provoked these similarities, and their results indicate that viruses hold vital secrets regarding the way different species have evolved.

The findings will have a great impact on the way researchers approach viral epidemics. Devastating viruses similar to HIV, for instance, have affected human beings and animals at many points in their long history. Seeing how cells have reacted to viruses of this type could help scientists glean a better understanding of how viruses work, and possibly lead to the discovery of how we can beat disease causing viruses for good, thus leading to greater health and a longer lifespan for humanity and other species.

Currently, viruses are taking countless lives, some of the most dangerous being the Marburg virus (which, like ebola, has a very high fatality rate), ebola (there are, thus far, five identified strains of the Ebola virus, which, like Marburg, has a fatality rate of 90 per cent), the Hantavirus (which actually comprises several types of virus and which can lead to lung disease, kidney failure and fever), some strains of bird flu, the Lass virus (whcich is transmitted by rodents), the Junin virus (which causes tissue inflammation), the Crima-Congo fever virus (transmitted by ticks and similar in its effects to Ebola and Margburg), the Machupo virus (which causes high fever and bleeding), the Kyasunur Forest Virus (which causes high fever, muscle pain and bleeding) and Dengue fever (passed on by a mosquito and boasting a very high fatality rate; Dengue is common in popular tourist destinations such as Thailand, India and the Philippines, affecting between 50 and 100 million people a year).

Thus far, viruses are treated by addressing specific symptoms and complications. For instance, with Ebola, the key is to provide fluids and keep electrolyte levels stable, to maintain oxygen levels and blood pressure, and to treat any infections that arise. For other viruses, researchers are working to discover vaccines which will keep them at bay. What would give scientists the upper hand by mimicking protein adaptations, however, is the ability to actually manipulate cell function, instead of merely responding to symptoms.