Religion and Ethics Forum
General Category => Science and Technology => Topic started by: Sriram on May 23, 2023, 07:21:11 AM
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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
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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
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Although they are more commonly associated with causing disease and, at times, devastating pandemics, viruses have also played an important role in human evolution
Even the ones involved in causing disease played an important role in human evolution.
Some of it was the source of the mammalian placenta.
That's not strictly true. the viral DNA supplied the code to synthesise a certain protein that is essential to mammalian placentas. The quote makes it sound like the entire placenta was encoded in the viral DNA.
Endogenous retroviruses are fascinating and provide almost incontrovertible evidence of evolution. For example, we share several ERVs with chimpanzees and those that we do share occur in exactly the same place in our respective genomes. The only credible explanation is that the ERVs were acquired by a common ancestor of humans and chimpanzees.
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Evolution is obviously a very complex process. There are multiple factors that contribute to the development of any species. As they say...a single integrated theory may be difficult to arrive at.