Throughout our evolution, viruses have infected an egg or sperm, incorporated themselves into the genetic code and passed on to future generations. While these viruses appear to have no ill effects on us, some of them have been known to cause cancer and other health problems in other mammals.
For geneticists, these ‘endogenous retroviruses’ (ERVs) serve another function – they can reveal details about a species evolution and genetic diversity.
According to a new study published in the journal Retrovirology, humans have far fewer ERVs than other mammals, including close relatives like chimpanzees. The study team said this discrepancy was probably due to human’s starting to use tools and weapons in conflicts – as opposed to biting and scratching each other like our primate cousins.
“Considering us simply as a primate species, the proportion of human individuals that are infected with retroviruses is much less than among our relatives such as chimpanzees,” said Robert Belshaw, a genomics professor from Plymouth University in the United Kingdom.
In the study, the scientists analyzed the genetic signature of the two opposite sides of viruses in 40 mammalian species, including humans. These edges are very similar when the virus first incorporates itself into the genome, but as they get random mutations over time, they slowly start to diverge. By monitoring this split, the study team could see how long the retrovirus had been in an animal’s genome.
Using this gauge, they learned that far fewer retroviruses were included in the genome for humans and other great apes during the last 10 million years compared to other animals. Even compared to animals very similar to us, humans are abnormal in not getting any new kinds of retroviruses in their DNA over the last 30 million years.
Read full, original article: Retroviruses reveal mammalian genetics