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HIV evolving 'into milder form'

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Re: HIV evolving 'into milder form'

#41

Post by acveilleux »

hazz wrote: post #9
zecg wrote: post #8

Earlier quoted context omitted.

Epstein-Barr virus is close to that ideal, 90-95% of adults have it. Unfortunately, it's connected with cancers: http://en.wikipedia.org/wiki/Epstein%E2%80%93Barr_virus

90-95% of adults had it at some point . Most people develop immunity to it and so it doesn't survive in them. I'd say the most successful virus in humans would be the common cold, given how frequently we seem to get it, although it's more of a massive family of virii.

Herpes Simplex is another example. A majority of americans are carriers.

Re: HIV evolving 'into milder form'

#42

Post by Justsignedup »

snowwrestler wrote: post #28
cJ0th wrote: post #26

Earlier quoted context omitted.

That's an interesting thought. It's like they posses "artificial intelligence", i.e. they behave like the famous paper clip maximizer.

Obviously viruses are not intelligent and they don't "want" to reproduce. However, they do reproduce, just like pretty much every other form of life. The question of why life does that is closely related to the question of what life is and how it came to exist. Those are deep questions and we don't really have a clue as to the answer right now. There's certainly nothing in the fundamental physical laws of the univers…

What if life is just an accidental misshapen rock which spreads itself changing constantly to adapt to ever hostile environments.

OMG What if we're the cancer of the universe, who is in itself a giant amoeba!??!!?!?!?

deep thoughts, with jack handy

Re: HIV evolving 'into milder form'

#43

Post by TeMPOraL »

Dn_Ab wrote: post #40
TeMPOraL wrote: post #27

Earlier quoted context omitted.

No, that's just evolution - plain, simple and extremely dumb. Viruses don't really "want" anything, they are just biomolecular machines that run around replicating themselves and screwing things up; some manage to copy themselves, some don't - and this way, generation after generation, you're left with those viruses that are good at copying themselves in the environment they're in. Evolution is a statistical phenomen…

In other settings, a simple approximation of what Evolution does will balance your portfolio and find Nash Equilibriums for zero sum games much more quickly than linear programming (query: multiplicative update evolution). Having to wait for things to die can be restrictive (but genomes are declarative, what does that buy?). Roughly, with what amounts to the assumption that Lamarckian evolution is more or less not tr…

Thanks for the references, I'll check them out after work :).

Re: HIV evolving 'into milder form'

#44

Post by jowiar »

ruairinewman wrote: post #21

Surely this process means that HIV is just as capable of evolving into something even more lethal over time, given the right environment? Given the relatively closed environment of a country like North Korea (for example) where diversity is restricted, its evolutionary path may take a different route than that observed by the University of Oxford research team?

Can random mutations make HIV more lethal? Sure. The argument here is that lethality makes HIV "less fit" from an evolutionary standpoint, which makes sense, as, given the means of transmission, killing the host isn't a particularly useful thing for the virus to do.

Re: HIV evolving 'into milder form'

#45

Post by Houshalter »

billpg wrote: post #6

What viruses "want" is to reproduce. Killing you is an unfortunate unplanned side effect. If only we could negotiate and agree to allow them to reproduce and not kill us, we'd all get along much better.

It's like the foxes that over-populate, eat all the rabbits and then all die. The foxes would be better not to reproduce past the limits of their environment, but each individual fox passes on more of it's genes if it doesn't restrain it's own breeding. And so those genes propagate to the detriment of the community.

You need very strong group selection to restrain breeding, and this becomes less and less likely as the population size increases (so each individual has less and less affect.) See The Tradgedy of Group Selectionism: http://lesswrong.com/lw/kw/the_tragedy_of_group_selectionism...

Even when organisms are selectively breed by scientists with group selection to limit their population size, they often just become cannibalistic rather than restrain their own reproduction. Killing someone else's kids is better than killing your own.

Essentially the same thing happens with viruses, where over reproduction means killing all the hosts cells.

Re: HIV evolving 'into milder form'

#46

Post by smorrow »

shittyanalogy wrote: post #24
billpg wrote: post #6

What viruses "want" is to reproduce. Killing you is an unfortunate unplanned side effect. If only we could negotiate and agree to allow them to reproduce and not kill us, we'd all get along much better.

I think the problem is DNA. If we could get rid of it we'd be better off.

The selfish DNA.

Re: HIV evolving 'into milder form'

#47

Post by GotAnyMegadeth »

ars wrote: post #3

That's pretty typical for parasites (which include viruses). Killing your host is never a good idea, the best parasites cause minimal disruption to their host. All animals and humans are infected with countless parasites, but you never notice. For example https://en.wikipedia.org/wiki/Face_mite (don't scratch).

Sometimes if the parasite moves from host to host as part of it's life cycle, and this can include aiding the death of one host. An example of this is a parasite that causes frogs to grow extra legs so that they are easier to catch for birds. The parasite then transfers to the bird, where it can lay it's eggs.

http://phenomena.nationalgeographic.com/2013/02/13/a-flurry-...

Re: HIV evolving 'into milder form'

#48

Post by kale »

egeozcan wrote: post #25
learnstats2 wrote: post #22

Earlier quoted context omitted.

This negotiation is rather weak since it doesn't recognise the passage of time. Once the viruses have reproduced to their satisfaction, they can renege on the deal when humans have a weaker negotiating position. That is to say, "Don't negotiate with terrorists." Fortunately the human/mammalian immune system does not typically permit this kind of deal. With a few exceptions: including HIV.

If killing you means that the pathogen can spread more rapidly, it will evolve to do so. I don't see the HIV virus gaining anything by killing the host as it depends mostly on sexual intercourse to spread. Correct me if I'm wrong, but, Ebola would have been a better example in this case, I suppose.

You are correct, Ebola's high mortality rate is a by-product of how it spreads.

Ebola virus is successful at spreading due to the fact that it's in various fluids secreted by endothelial cells (which are everywhere in the body). The virus has mutated to let those tissues start to "leak", which means a person infected with Ebola is more likely to leak fluids (which is why it sometimes causes bleeding out of mucous membranes). Since there is an increase in the endothelial fluids released, there is more exposure to those trying to treat a patient with Ebola.[1]

The way the virus spreads (increased discharge of endothelial fluids) is what causes it to be so fatal, which is a by-product.

[1] Great overview of the virus: http://arstechnica.com/science/2014/11/understanding-the-ebo...

Re: HIV evolving 'into milder form'

#49

Post by mikeash »

snowwrestler wrote: post #28
cJ0th wrote: post #26

Earlier quoted context omitted.

That's an interesting thought. It's like they posses "artificial intelligence", i.e. they behave like the famous paper clip maximizer.

Obviously viruses are not intelligent and they don't "want" to reproduce. However, they do reproduce, just like pretty much every other form of life. The question of why life does that is closely related to the question of what life is and how it came to exist. Those are deep questions and we don't really have a clue as to the answer right now. There's certainly nothing in the fundamental physical laws of the univers…

I thought the question of why life reproduces is easy to answer: things that reproduce become greater in number, and things that reproduce better become even greater in number than things that reproduce worse. Thus, the world is filled with things that reproduce really well.

Re: HIV evolving 'into milder form'

#50

Post by eru »

hazz wrote: post #9
zecg wrote: post #8

Earlier quoted context omitted.

Epstein-Barr virus is close to that ideal, 90-95% of adults have it. Unfortunately, it's connected with cancers: http://en.wikipedia.org/wiki/Epstein%E2%80%93Barr_virus

90-95% of adults had it at some point . Most people develop immunity to it and so it doesn't survive in them. I'd say the most successful virus in humans would be the common cold, given how frequently we seem to get it, although it's more of a massive family of virii.

The common cold describes a bunch of symptoms that can be triggered by quite a few different viruses.
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