Hi everyone,
Here is a BBC article about viruses and their role in evolution.
https://www.bbc.com/future/article/20230519-the-viruses-that-helped-to-make-you-human***********
Although they are more commonly associated with causing disease and, at times, devastating pandemics, viruses have also played an important role in human evolution – and without them you wouldn't be here at all.
Within the last 25 million years, the ancestors of the lizards were infected by a virus that incorporated some of its own DNA into their genome. But instead of being harmed, the lizards somehow co-opted the viral DNA and used it to develop their first placentas. Thanks to the virus, the lizards evolved a new organ.
The unusual thing about this story, however, is that it is not unusual. About a tenth of the human genome comes from viruses, and that viral DNA has played crucial roles in our evolution. Some of it was the source of the mammalian placenta. Other bits are involved in our immune response against disease and in the formation of new genes. Without viruses, humans could not have evolved.
The final lesson is that humans are truly a mosaic species. Many of us have some DNA, around 2% of our genome, from Neanderthals. Some populations also have some DNA from another extinct hominin group, the Denisovans. And all of us get around 8% of our genome from viruses.
"If you think about the human gene catalogue, it's kind of almost an existential question," says Feschotte. Around 20,000 protein-coding genes are known, and a comparable quantity of our DNA comes from viruses. "It's kind of mind blowing."
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Cheers.
Sriram
