[neilep (OP)]

Hi All,

If the premise of most living things is to procreate, then what is the rationale of a disease/invading organism doing when it kills the host ?..which would ultimately lead to it's own demise !..Surely this serves no long term purpose at all !

whjaafink ?



Neil

[Karen W.]

Hi Sheepy,

huh ha.. that's a good question as it does seem self defeating.. doesn't it?

[neilep (OP)]

Hi Sheepy,

huh ha.. that's a good question as it does seem self defeating.. doesn't it?

Hi Kareny Mam,

Thanks for your response (ewe should post more often ewe know !  [])

yes, that is what I was thinking last night....I can't see the point of something living which concludes with it's own demise and no offspring !

[Karen W.]

y/w

[neilep (OP)]

y/w

??

[Karen W.]

your welcome

[neilep (OP)]

your welcome

M/P

[Karen W.]

My Pleasure too!

[Variola]

Hi All,

If the premise of most living things is to procreate, then what is the rationale of a disease/invading organism doing when it kills the host ?..which would ultimately lead to it's own demise !..Surely this serves no long term purpose at all !

whjaafink ?



Neil

Hello ewe

Well there is a school of thogutht that suggests that viruses usually exist quite happily within their natural host, and it only when they mutate and cross species that they enter hosts that they can kill.
Its not in the viruses interest in infect a host that it cannot co-exist with.

[RD]

Q. What's the Point Of A Virus Living If It Kills The Host ?

A. The process by which the virus spreads may also kill the host, e.g. hemorrhagic fevers like Ebola virus, i.e. bleeding the host (ususally to death) over a few weeks helps spread the virus to other hosts via blood. The gain of increased viral spread to other hosts outweighs the loss of killing a host: a net increase in the number of copies of viral genes.

[rosy]

You assume a "point". We use phrases when talking about evolution which suggest that (genetic) survival is in some way an aim, whereas for things like viruses to speak of an aim is rather misleading. It happens to be the case that if the genetic material of a virus is passed on, whether in a different organism or the same one, that genetic material will persist.. if not, then it will die out.
This is, in part, why viruses tend to move towards being less immediately lethal: if they kill their host too quickly they may not have time to be passed on - AIDS is reportedly becoming, even in the relatively short time it's been around, less rapidly lethal (even where the drugs aren't available) because an individual who lives longer has more time to infect other people, so those less immediately lethal forms of the virus will be transferred to more other hosts.

[dlorde]

This is, in part, why viruses tend to move towards being less immediately lethal: if they kill their host too quickly they may not have time to be passed on - AIDS is reportedly becoming, even in the relatively short time it's been around, less rapidly lethal (even where the drugs aren't available) because an individual who lives longer has more time to infect other people, so those less immediately lethal forms of the virus will be transferred to more other hosts.

Certainly, enduring viruses do tend to reduce in lethality, but unfortunately viruses do reproduce extremely rapidly, so even a virus with a high 'immediate' lethality can sweep through a population, killing a large percentage before becoming less lethal or virulent. The rapid mutation rate means that this is not such a remote possibility as many people assume.

[rosy]

Certainly, enduring viruses do tend to reduce in lethality, but unfortunately viruses do reproduce extremely rapidly, so even a virus with a high 'immediate' lethality can sweep through a population, killing a large percentage before becoming less lethal or virulent. The rapid mutation rate means that this is not such a remote possibility as many people assume.

Can and, indeed, does.. hence the utter mess caused by the influenza outbreak in 1918. I didn't intend to imply otherwise.

[dlorde]

Can and, indeed, does.. hence the utter mess caused by the influenza outbreak in 1918. I didn't intend to imply otherwise.

I wasn't intending to correct or criticise your post, just adding a bit more to it []

Apologies if it came across negatively.

[lyner]

There are millions of virus types which just 'exist' happily with their hosts. I should say that they could be said to be successful.
With the rapid communication between all members of the human population, the situation has changed; what was a useful characteristic for a virus, ten thousand years ago, could be a less useful characteristic now. Huge epidemics don't help the population of a virus at all, in the short term - but if they can always wait  until the host population re grows.
It may be easy to decide how to judge success for a species like Humans but the concept of success is more difficult with parasites - just 'not dieing out' is success?

[dlorde]

It may be easy to decide how to judge success for a species like Humans but the concept of success is more difficult with parasites - just 'not dieing out' is success?

Partly it may be difficult because they themselves don't have concepts - it's a purely anthropomorphic interpretation we apply to them (Dawkins may have confused some people with his apparently contradictory titles, 'The Selfish Gene' - suggesting motivation/intent, and 'The Blind Watchmaker' - suggesting unguided/undirected/purposeless assembly)... []

I guess we may as well say that success for a parasite is continuing to survive, as without that they wouldn't be here to be judged successful or not...  []