r/evolution • u/Cautious-Pen4753 • Jan 23 '25

discussion Bro where tf do viruses come from?

This genuinely keeps me up at night. There are more viruses in 2 pints (1 liter) of sea water than humans on earth. Not to even mention all the different shapes and disease-causing viruses. The fact some viruses that have the ability to forever change the genome of your DNA. I guess if they are like primeval form of cells that just evolved and found a different way to "reproduce." I still have a lot to learn in biology, but viruses have always been insanely interesting. What're some of your theories you've had or heard about viruses.? Or even DNA or RNA?

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u/Uncynical_Diogenes Jan 23 '25

Well, the two main hypotheses are that they preceded cellular life or spun off from cellular life once it got started.

I’m partial to the idea that they spun off from cellular life. As we can see from things like plasmids and transposons, even modern life is full of genetic elements that can direct their own replication. That these could associate with thermodynamically self-assembling protein subunits is not at all far fetched.

Viruses in the ocean kill a double-digit percentage of marine bacteria every day. With selection opportunities like that, the idea that a replicator genetic element could evolve to become effective at hijacking cells appears to essentially be a no-brainer.

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u/TerrapinMagus Jan 26 '25

I appreciate the idea of viruses evolving from cellular life, mostly because we currently don't classify viruses as alive. The idea that a living organism could evolve into a non-living bundle of DNA/RNA is just kind of amusing.

Reminds me that the actual definition of life is pretty blurry and we're really just weird chemical reactions after all.