3 ms·

I’m not a virologist, but I did pay attention in biology class fwiw. Evolutionary, a virus that can only replicate a few times is a dead end. That’d be like mu

I’m not a virologist, but I did pay attention in biology class fwiw. Evolutionary, a virus that can only replicate a few times is a dead end. That’d be like mule, a viable life form, but one that cannot reproduce successfully. Think about the mechanisms of cells with generation limits, I’d intuit that they preform functions related to morphogenisis (we only want this bone to be this long), and forcing evolutionary iteration by limiting the maximum age of a individual. I’d posit that extreme longevity is an affront to evolution. I could be totally off my rocker with the second part, but I’d like to think that a basic knowledge of biology and an obsession with cellular automata might have given me a useful intuition.

jacquesm 7y ago
I was thinking more along the lines of a virus that is able to reproduce indefinitely in one species, but after a species jump ends up being able to reproduce only a limited number of generations due to the copying mechanism being subtly different in the host cell of the new species. But you're right that from an evolutionary standpoint such a virus would be a dead end if it happened in any species. It would very much depend on how - and if - the different ribosomes and other cell mechanisms responsible for copying the viruses RNA (or DNA in some cases) would deal with the virus. The effect you'd see would be a species jump, followed by a very virulent episode fizzling out when the copy errors accumulated to the point that the copies would no longer be viable.
- unsrsly 7y ago
  This is an interesting question! Note that human stem cells and cancer cells do not have a limit on how many times they can divide. This is because they possess the enzyme telomerase. Also, note that in human reproduction, there is an unbroken lineage of cell divisions through generations (egg and sperm are produced by specialized cell divisions called meiosis, and combine in sexual reproduction to develop a new human who can eventually produce more egg or sperm). However, it is true that differentiated somatic cells (most of the cells in your body) cannot divide indefinitely. A virus, unlike a differentiated somatic cell, does not have an intrinsic limit to how many times it can replicate. It hijacks cellular machinery to make an exact replica of itself (+/- any replication errors a.k.a. mutations that occur). However, a virus that becomes evolutionarily unfit could go extinct. If you look at phylogenetic trees of viruses, there are many branches that go extinct (become a dead end). But there are other branches that continue succeeding. All of this is driven by evolutionary dynamics rather than by a lack of telomerase leading to a hard limit on the number of times the virus can replicate. Now, just to blow your mind, oncogenic viruses like certain strains of HPV can induce human cells to produce telomerase and become able to divide indefinitely! Wowww this is so confusing!

jacquesm 7y ago

I was thinking more along the lines of a virus that is able to reproduce indefinitely in one species, but after a species jump ends up being able to reproduce only a limited number of generations due to the copying mechanism being subtly different in the host cell of the new species. But you're right that from an evolutionary standpoint such a virus would be a dead end if it happened in any species. It would very much depend on how - and if - the different ribosomes and other cell mechanisms responsible for copying the viruses RNA (or DNA in some cases) would deal with the virus. The effect you'd see would be a species jump, followed by a very virulent episode fizzling out when the copy errors accumulated to the point that the copies would no longer be viable.

unsrsly 7y ago
This is an interesting question! Note that human stem cells and cancer cells do not have a limit on how many times they can divide. This is because they possess the enzyme telomerase. Also, note that in human reproduction, there is an unbroken lineage of cell divisions through generations (egg and sperm are produced by specialized cell divisions called meiosis, and combine in sexual reproduction to develop a new human who can eventually produce more egg or sperm). However, it is true that differentiated somatic cells (most of the cells in your body) cannot divide indefinitely. A virus, unlike a differentiated somatic cell, does not have an intrinsic limit to how many times it can replicate. It hijacks cellular machinery to make an exact replica of itself (+/- any replication errors a.k.a. mutations that occur). However, a virus that becomes evolutionarily unfit could go extinct. If you look at phylogenetic trees of viruses, there are many branches that go extinct (become a dead end). But there are other branches that continue succeeding. All of this is driven by evolutionary dynamics rather than by a lack of telomerase leading to a hard limit on the number of times the virus can replicate. Now, just to blow your mind, oncogenic viruses like certain strains of HPV can induce human cells to produce telomerase and become able to divide indefinitely! Wowww this is so confusing!