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Perhaps the problem is your choice of words. Saying "selection pressure" implies intent, determination, a collective mission, if you will. Evolution has none o

Perhaps the problem is your choice of words. Saying "selection pressure" implies intent, determination, a collective mission, if you will. Evolution has none of those drivers. It has no objectives. It sets no goals. And it certainly does not operate in some collective purpose driven form within a population. It's random mutations that either survive the environmental contex within which they exist, or they don't. In this case the fact that more people are infected does not mean that we are at the doorstep of a "super-ebola" mutation any time soon. It could take ONE mutation or 100 MILLION YEARS of intense mutations to arrive at "super-ebola". Nobody knows. The virus certainly isn't under any "selection pressure" to do a darn thing. It could become perfectly benign in six months just as much as it could become horrifically good at killing us by the millions.

lotsofmangos 12y ago
Selection pressure is the term used widely in evolutionary biology. If you can't get past that choice of words, you wouldn't be able to get anywhere in actually studying the subject, as that choice of words is used throughout. http://scholar.google.co.uk/scholar?q=selection+pressure+evolution http://scholar.google.co.uk/scholar?q=selection+pressure+evo...
lindenr 12y ago
You said: "Saying "selection pressure" implies intent, determination, a collective mission, if you will. Evolution has none of those drivers. It has no objectives. It sets no goals. And it certainly does not operate in some collective purpose driven form within a population." danieltillett said: "At the moment the speed of disease progression to death is so fast that it is slowing the spread of Ebola. If the Ebola took longer to kill it would infect more people." This seems like a true statement and in line with your own opinion; I can't quite see what you are objecting to.
- robomartin 12y ago
  The death of the infected isn't necessarily the end of the virus. It looks like a police officer inspecting the home of the guy who just died in Texas has now contracted ebola. As I understand it he inspected the home days after the patient had been in isolation at the hospital. Apparently there was vomit, fecal matter, blood and who knows what else in there. Why he went in there without protective gear is incomprehensible to me. The point is that death isn't the end of the virus, it's the end of the host. That's why they are cremating the guy who just died.
danieltillett 12y ago
I guess I could be accused of using technical language with an audience that does not have an biology background. "Selection pressure" means something specific in biology and I used it in that manner. To put what I said in layman’s terms an Ebola viral strain that has by chance a mutation that results in slower disease progression will have more opportunities to infect people than one that kills people faster. If out of the trillion and trillions of new Ebola viral particles being created every second in west Africa one viral particle were to be randomly created that happened to kill people slower, then anyone infected with this new strain would be more likely to live longer than if they had been infected with an original virus particle. This person would then have a greater chance to infect new people and so on. Such a strain would be more contagious, and depending on the exact properties of the strain it may be able to spread even in western countries. I am not saying that this is likely (nobody know), but I would prefer we stop generating all those trillions of random Ebola viral particles and so end this rather dangerous experiment.
- shasta 12y ago
  The selection pressure doesn't seem to be that huge to me. There are only on the order of 10,000 human cases. That those cases are caused by trillions of ebola viruses doesn't seem relevant to measuring evolutionary pressure.
- robomartin 12y ago
  Thanks, learned something new. Obviously not a biologist. Perhaps a link to the definition would have been useful being that one can't assume the audience to familiar with terms that can easily be confused for something else. Now to make sure I understand it. Are you proposing that selection pressure is being exerted, among other things, by he time it takes for the virus to kill the host? Well, I guess one could say everything exerts selection pressure. What makes you focus on time-to-kill? Is there any evidence that time-to-kill is the most important variable here? For example, if the virus mutated in such a way that it caused the host to not develop a fever until a few days after it is communicable it could become really deadly very quickly? The same would be the case if it caused more violent coughing, etc. In other words, now that I understand how you are using the term "selection pressure" I also understand that time-to-kill is but one of the factors causing it. Why do you focus on time-to-kill when arguably it is the easiest to control by means of isolation. To further clarify, if someone gets sick with the current time-to-kill duration it will be identified and dealt with in N days. If time-to-kill doubled due to an unfortunate mutation it is unlikely that it will take 2N days to identify and deal with a patient. In other words, the fact that it takes twice as long for the virus to kill the patient is probably irrelevant. This, of course, only holds if the fabric of society holds. If you have sick and contagious people roaming the streets coughing on everyone they come across all bets are off. Then again, that would be true without any change to the time-to-kill time. So, yeah, not sure I get why you think time-to-kill selection pressure is important in the context of a society that hasn't completely broken down.

lotsofmangos 12y ago

Selection pressure is the term used widely in evolutionary biology. If you can't get past that choice of words, you wouldn't be able to get anywhere in actually studying the subject, as that choice of words is used throughout. http://scholar.google.co.uk/scholar?q=selection+pressure+evolution http://scholar.google.co.uk/scholar?q=selection+pressure+evo...

lindenr 12y ago

You said: "Saying "selection pressure" implies intent, determination, a collective mission, if you will. Evolution has none of those drivers. It has no objectives. It sets no goals. And it certainly does not operate in some collective purpose driven form within a population." danieltillett said: "At the moment the speed of disease progression to death is so fast that it is slowing the spread of Ebola. If the Ebola took longer to kill it would infect more people." This seems like a true statement and in line with your own opinion; I can't quite see what you are objecting to.

robomartin 12y ago
The death of the infected isn't necessarily the end of the virus. It looks like a police officer inspecting the home of the guy who just died in Texas has now contracted ebola. As I understand it he inspected the home days after the patient had been in isolation at the hospital. Apparently there was vomit, fecal matter, blood and who knows what else in there. Why he went in there without protective gear is incomprehensible to me. The point is that death isn't the end of the virus, it's the end of the host. That's why they are cremating the guy who just died.

danieltillett 12y ago

I guess I could be accused of using technical language with an audience that does not have an biology background. "Selection pressure" means something specific in biology and I used it in that manner. To put what I said in layman’s terms an Ebola viral strain that has by chance a mutation that results in slower disease progression will have more opportunities to infect people than one that kills people faster. If out of the trillion and trillions of new Ebola viral particles being created every second in west Africa one viral particle were to be randomly created that happened to kill people slower, then anyone infected with this new strain would be more likely to live longer than if they had been infected with an original virus particle. This person would then have a greater chance to infect new people and so on. Such a strain would be more contagious, and depending on the exact properties of the strain it may be able to spread even in western countries. I am not saying that this is likely (nobody know), but I would prefer we stop generating all those trillions of random Ebola viral particles and so end this rather dangerous experiment.

shasta 12y ago
The selection pressure doesn't seem to be that huge to me. There are only on the order of 10,000 human cases. That those cases are caused by trillions of ebola viruses doesn't seem relevant to measuring evolutionary pressure.
robomartin 12y ago
Thanks, learned something new. Obviously not a biologist. Perhaps a link to the definition would have been useful being that one can't assume the audience to familiar with terms that can easily be confused for something else. Now to make sure I understand it. Are you proposing that selection pressure is being exerted, among other things, by he time it takes for the virus to kill the host? Well, I guess one could say everything exerts selection pressure. What makes you focus on time-to-kill? Is there any evidence that time-to-kill is the most important variable here? For example, if the virus mutated in such a way that it caused the host to not develop a fever until a few days after it is communicable it could become really deadly very quickly? The same would be the case if it caused more violent coughing, etc. In other words, now that I understand how you are using the term "selection pressure" I also understand that time-to-kill is but one of the factors causing it. Why do you focus on time-to-kill when arguably it is the easiest to control by means of isolation. To further clarify, if someone gets sick with the current time-to-kill duration it will be identified and dealt with in N days. If time-to-kill doubled due to an unfortunate mutation it is unlikely that it will take 2N days to identify and deal with a patient. In other words, the fact that it takes twice as long for the virus to kill the patient is probably irrelevant. This, of course, only holds if the fabric of society holds. If you have sick and contagious people roaming the streets coughing on everyone they come across all bets are off. Then again, that would be true without any change to the time-to-kill time. So, yeah, not sure I get why you think time-to-kill selection pressure is important in the context of a society that hasn't completely broken down.