4 ms·

That is not what typically happens though. There's no reason to expect it. It would be an anomaly

deleted 5y ago
[deleted]
heavyset_go 5y ago
Except that happens all of the time, there's plenty of reason to expect it and it wouldn't be an anomaly. From the AP's "Viruses can evolve to be more deadly" article[1]: > Day said there are documented cases of animal viruses that evolved over time to become more lethal, including myxoma virus in rabbits and Marek’s disease in chicken. > Some viruses provoke severe symptoms in their hosts that make it easier to transmit the virus to others. But those same symptoms can wind up killing the hosts. > Adalja said one example is Ebola, a deadly virus that spreads through the blood and body fluids of infected people. Another example is norovirus, which causes diarrhea and vomiting, and leads to hundreds of deaths each year in the U.S. > “The virus, speaking anthropomorphically, just wants to spread and have its genes replicated,” said Adalja. “If the best way for it is to spread by causing severe symptoms it will continue to do that.” [1] https://apnews.com/article/fact-checking-011488089270 https://apnews.com/article/fact-checking-011488089270
- dude187 5y ago
  That's not the norm, that's the unexpected anomaly
  - jacquesm 5y ago
    No, that's the norm. The people that are repeating the 'viruses evolve to become more benign' line are about 40 years behind the times in terms of science as it is currently accepted. Viruses evolve to spread as efficiently as possible, what happens to the host after they have spread is from a viral evolution point of view utterly irrelevant. So they can and do evolve to be more lethal. Maybe it takes a bit longer before you die but that's perfectly fine.
    - dude187 5y ago
      > No, that's the norm. How is the norm for viruses to continue to become more lethal? That does not align with anything I've ever heard. That link doesn't even claim that, and that's a baseless "fact check" done by a mathematician acting as a false authority.
      - jacquesm 5y ago
        > How is the norm for viruses to continue to become more lethal? The norm is for viruses to end up somewhere in the middle, but chances are that the lethality is still very high. The whole idea that viruses evolve to be less lethal simply isn't true and very much outdated. > That does not align with anything I've ever heard. That is possible, it is a pretty persistent thing but it has been dealt with decisively since the 80's: https://www.researchgate.net/publication/224043344_Coevolution_Of_Hosts_and_Parasites https://www.researchgate.net/publication/224043344_Coevoluti... In a nutshell: it is likely that viruses (and other parasites) change once they have made their jump to a new species. This change is mostly random, selection pressure will lead to maximizing for R0, which may or may not lead to a lower level of lethality but this is by no means guaranteed. Some outliers may evolve to become more lethal, some other outliers may evolve to be (much) less lethal, but for the bulk an intermediary level of lethality (which can still be very high) is the normal outcome. This is experimentally confirmed over and over again over the timescales that we have been doing these. The shortest way in which you can condense all this is: "to a virus it is replication that matters, not what happens to the host after it has replicated". Of course viruses don't have any conscious plan but the evolutionary mechanism selects for (more) successful reproduction so it will seem like that from the outside.

deleted 5y ago

[deleted]

Except that happens all of the time, there's plenty of reason to expect it and it wouldn't be an anomaly. From the AP's "Viruses can evolve to be more deadly" article[1]: > Day said there are documented cases of animal viruses that evolved over time to become more lethal, including myxoma virus in rabbits and Marek’s disease in chicken. > Some viruses provoke severe symptoms in their hosts that make it easier to transmit the virus to others. But those same symptoms can wind up killing the hosts. > Adalja said one example is Ebola, a deadly virus that spreads through the blood and body fluids of infected people. Another example is norovirus, which causes diarrhea and vomiting, and leads to hundreds of deaths each year in the U.S. > “The virus, speaking anthropomorphically, just wants to spread and have its genes replicated,” said Adalja. “If the best way for it is to spread by causing severe symptoms it will continue to do that.” [1] https://apnews.com/article/fact-checking-011488089270 https://apnews.com/article/fact-checking-011488089270

dude187 5y ago
That's not the norm, that's the unexpected anomaly
- jacquesm 5y ago
  No, that's the norm. The people that are repeating the 'viruses evolve to become more benign' line are about 40 years behind the times in terms of science as it is currently accepted. Viruses evolve to spread as efficiently as possible, what happens to the host after they have spread is from a viral evolution point of view utterly irrelevant. So they can and do evolve to be more lethal. Maybe it takes a bit longer before you die but that's perfectly fine.
  - dude187 5y ago
    > No, that's the norm. How is the norm for viruses to continue to become more lethal? That does not align with anything I've ever heard. That link doesn't even claim that, and that's a baseless "fact check" done by a mathematician acting as a false authority.
    - jacquesm 5y ago
      > How is the norm for viruses to continue to become more lethal? The norm is for viruses to end up somewhere in the middle, but chances are that the lethality is still very high. The whole idea that viruses evolve to be less lethal simply isn't true and very much outdated. > That does not align with anything I've ever heard. That is possible, it is a pretty persistent thing but it has been dealt with decisively since the 80's: https://www.researchgate.net/publication/224043344_Coevolution_Of_Hosts_and_Parasites https://www.researchgate.net/publication/224043344_Coevoluti... In a nutshell: it is likely that viruses (and other parasites) change once they have made their jump to a new species. This change is mostly random, selection pressure will lead to maximizing for R0, which may or may not lead to a lower level of lethality but this is by no means guaranteed. Some outliers may evolve to become more lethal, some other outliers may evolve to be (much) less lethal, but for the bulk an intermediary level of lethality (which can still be very high) is the normal outcome. This is experimentally confirmed over and over again over the timescales that we have been doing these. The shortest way in which you can condense all this is: "to a virus it is replication that matters, not what happens to the host after it has replicated". Of course viruses don't have any conscious plan but the evolutionary mechanism selects for (more) successful reproduction so it will seem like that from the outside.