The findings suggest our genome is even less human than scientists previously thought.
It’s quite mind boggling to think that eight percent of human DNA is not human at all, but rather remnants of viral fragments lurking within our genome. It’s believed that these viral DNA fragments were incorporated into the human genome by infections of our ancestors hundreds of thousands of years ago.
In a study looking at 2,500 human DNA profiles, researchers at Tufts University and the University of Michigan medical school have discovered nineteen new pieces of non-human DNA within the human genome, including one whole retrovirus.
The startling discovery found that one specific stretch of DNA in 50 of the 2,500 DNA profiles analyzed, contained the full genetic recipe for an entire virus! It’s not yet known if the retrovirus can replicate and reproduce from within human DNA, but according to the research team, previous studies have shown that humans can be affected by endogenous viruses within their DNA.
In addition to the complete retrovirus discovered, the team of researchers also confirmed that they found seventeen new fragments of viral DNA within the human genomes they studied. The 2,500 DNA profiles that were studied came from various populations from around the world, however a large proportion came from Africa, where our ancestors migrated from initially.
“This is a thrilling discovery. It will open up many doors to research,” Co-author Julia Wildschutte, PhD said in a media release. “What’s more, we have confirmed in this paper that we can use genomic data from multiple individuals compared to the reference human genome to detect new HERVs. But this has also shown us that some people carry insertions that we can’t map back to the reference.”
HERVs (human endogenous retroviruses) are a group of ancient viruses that infected our ancestors with their genetic material, and remnants of the viral DNA have been copied and passed down generation after generation. They actually form part of the same group of viruses that include the human immunodeficiency virus, which causes AIDS.
Co-author Zachary H. Williams, PhD said in a media release, “Many studies have tried to link these endogenous viral elements to cancer and other diseases, but a major difficulty has been that we haven't actually found all of them yet.”
“A lot of the most interesting elements are only found in a small percentage of people, which means you have to screen a large number of people to find them,” Williams continued.
This newly discovered retrovirus is the second whole provirus to be discovered lurking within human DNA. With more extensive research of human DNA continuing in the future, the likelihood that we may find we are not as human as previously thought is entirely possible.
The study was published in the Proceedings of the National Academy of Sciences.
The animated video below gives a brief description of the basics of DNA, genes, and heredity.