This is just a thought that I had that seemed worthy of discussion.
Organisms often evolve in ways to outsmart, hide from, or otherwise thwart the efforts of those that prey upon them. It is one of the primary catalysts for evolutionary change.
Since we as humans sit atop our food chain, we don’t have the typical “prey”, so the organisms that cause us the most grief are viruses and bacteria. Thus, diseases and illnesses have taken the place of lions and tiger and bears, and have become an instrument by which nature thins our herds, so to speak. However, it seems that there is some evidence that suggests that evolution might actually result in our being immune to certain ailments. For instance, Europeans, having built up immunities to smallpox, were hardly affected when smallpox ravaged the native populations of the Americas. That’s not to say that Europeans were “more evolved” than native Americans, there just existed within them an aspect of their evolution that until then was not required by native Americans.
Is it safe to say that these natural immunities are a form of evolution? If so, with the invention of antibiotics and other such drugs that fight off infections or diseases, have we in some way derailed the natural course of evolution? After all, if our body does not need to fight off an infection due to the use of an external antibiotic, why bother to evolve our own immunities?
Needless to say, I am not in favor of throwing away all antibiotics, but I do wonder if despite the great amount of good they do, that there is a negative side to their use.
Antibiotics, surgery, advanced genetic treatment (when and if) are part of the environment in which we live. Humans will adapt to that environment over a long, long period of time. If the environment changes, for example advanced medical treatement is no longer available, then those who can survive without it will, others will not. If none can survive the new environment then humans will become extinct. This latter possibility seems unlikely to me.
I don’t believe it is possible to escape the natural selection filter.
As of this point, the environment is changing at a rate which is orders of magnitude too large for evolution to keep up with it. Medicine is a very, very small part of that, and really can’t take any significant part of the blame.
Yes it is evolution, drugs will change us in that people with less resistance to certain diseases will still live to pass on their weaker genes, but it won’t eliminate the immune system, just as some of those bubble boys how having no immune system feels.
I predict soon we will come up with innoculations that streanghthen the immune system to counteract the weakening it will recieve via less diseases for it to practice on.
hrm… can someone clarify about the smallpox?
i thought smallpox was a threat until they discover cowpox?
are certain people immune to smallpox cuz of genes inherited?
using antibiotics is bad except when you are seriously ill. the reason is that it builts up bacteria immunity to these antibiotics.
as for evolution, we dunno what is better genes. if someone has a gene that enable them to be immune to a certain disease, does not mean that gene is superior. reason is that we dunno genetics enough to come to conclusions. we have no idea what one gene do to other things. in life, there are always trade offs. what is that person trading off to gain immunity to that disease?
case in point, malaria… there are certain people who can survive malaria. if you think this is good, then think again- they are more susceptible to other medical conditions. in africa, people can get sickle cell anemia if both their parents have the gene to survive malaria.
i am just trying to illustrate a point here.
I also want to say that Ultrafilter’s comment:
"As of this point, the environment is changing at a rate which is orders of magnitude too large for evolution to keep up with it. "
This is not a one time phenomenon. Earth has gone through changes that evolution cannot keep up. If you look at the history of organisms, Earth has changed many many times. People are not changing Earth in ways that Earth has not seen. That does not mean we should pollute, cuz if you look at what happens when Earth goes through rapid major changes, is that new organisms dominate the planet. We will like to keep our place on top of the food chain, so let us not pollute.
nth, regarding smallpox - when viruses infect a cell, they are sliced up and these pieces are presented on the surface of that cell to allow the immune system to form a defense. T cells bind to these antigens, then will stimulate the appropriate antibodies or other defenses. The component responsible for presenting viral peptides on cell surfaces is called MHC, or major histocompatibility class.
There are 2 major MHCs, I and II, but I believe people of European decent have something like 40 different combinations of MHCs they can make, and Africans have ~44 combinations. This allows these groups to present diseases more easily. Native Americans, on the other hand, only have 4 MHC combinations - this is why Smallpox killed millions of native Americans while not greatly affecting Europeans (who also had been in contact with Smallpox for hundreds of years which may have increased immunity).
“anti-evolutionary” is a bit misleading; it’s not as if Evolution has an agenda.
Yes, medicines allow us to become less resistant to diseases and provide a selective force that can favour medicine-resistant strains of disease.
If we didn’t use medicines so much, then yes, we would evolve better immunities, but consider what that means; we’re not talking about acquired immunity (the kind that stops most people getting chicken pox twice) being passed on to offspring - the human race would evolve better immunity to disease because the weak would die.
Evolution is not about “keep[ing] up”. It is not a process that can be outpaced or circumvented.
Natural selection, the process most people equate to “evolution”, operates by selecting from the current population those traits which are most detrimental and most beneficial to the individuals within that population, based on the current environment. Those with detrimental traits are less likely to reproduce, thus those traits are less likely to continue on. Those with traits which bestow an advantage render those individuals more likely to reproduce, thus increasing the relative frequency of those traits in the population.
Regardless of the environment, there will be advantageous and disadvantageous traits (and ones which are, for the time being at least, selectively neutral). Thus, selection is continual.
Note especially that, as David Simmons points out, we are capable of heavily modfying our environment (as are, to at least some degree, all organisms). All such processes accomplish are altering the parameters which determine the relative detriment or benefit of a given trait; they do not exempt us from selection and subsequent evolution.
I am more confused. You are telling me Native Americans have only 4 MHC back then right?
I thought ability to fight invading virus/bacteria was through previous exposure to same or similar invaders. Native Americans maybe exposed to less invaders, so thus have weaker immune system when exposed to non-familiar invaders.
But are you hinting that Native American genome for immune system is a lot different than Europeans?
I always thought and maybe incorrectly that our genes are similar but cuz of lack of exposure, we have a harder time to recognize the invaders before it is too late and you get very sick.
Just want to point out that humans will evolve with better immunity not necessarily with the weak dying out, but simply unable to have a successful reproducing offspring.
The weak can die all it wants as long as before they die, they have lots of children who have lots of children, etc. This won’t help evolve a better immune system.
Just something we tend to forget when talking about evolution.
err… all I meant by that statement is that if a species goes extinct, then for that species, the evolution of that species has failed to keep up. obviously, i used the wrong word. i guess i should said,
“Earth has gone through changes that dominant species have failed to adapt to.”
Instead of:
“Earth has gone through changes that evolution cannot keep up.”
My whole point was that after we finished polluting this world. Earth goes on and living things live on, but we probably won’t.
This whole “keeping up” was regarding Ultrafilter’s comments.
With modern medicine rather than survival of the fittest determining the out come of who lives and dies, human evolution may be in limbo.
We are the first species to ever roam the earth that is able to pass on inferior genes (with impunity) that natural selection would wipe out. I think it is counter evolutionary!!
Certainly, we’re changing which genes are more important. But that doesn’t change evolution. In our pre-medical past, resistance to diseases would be very advantageous, because diseases were likely to kill or sterilize if they took hold. Nowadays, though, if a person has, say, diabetes, or contracts anthrax, it’s not a big deal, since that person can get medications which enable the disease to be cured or tolerated. A more beneficial gene now might be one which makes it easier for a person to earn the money to buy medications. Or, even more so, one which makes the person more attractive to members of the opposite sex (or even many members of the opposite sex). So it used to be that we were evolving to be tough and strong, and now we’re evolving to be rich and beautiful. It’s still evolution.
Just as Chronos says. Medicine is not anti-evolutionary. It represents a change in circumstances, and we can expect evolution to adapt our descendants to the new circumstances. For example humans might adapt to medicine by investing less nutrients in making an immune system and more into running a reproductive system.
It is just that a human adapted to flourish in a different environment will be less suited to this environment than we are, and even more ill-suited to the environment of 100 years ago in which most of our social prejudices were formed. But then, so are we less than well-suited to the environment of our amphibian forebears.
“Fittest” has a meaning only in relation to what an organism is “fit” for. Genes are only “inferior” relative to the environment. Once again. Medical treatment is a part of our environment. If that environment lasts long enough humans will evolve in response to that. If that environment changes, like advanced medical treatment isn’t available any more, the humans fitted to the old environment will be at a disadvantage and will gradually die out to be replaced by humans fitted to the new environment.
“Fittest” has a meaning only in relation to what an organism is “fit” for. Genes are only “inferior” relative to the environment. Once again. Medical treatment is a part of our environment. If that environment lasts long enough humans will evolve in response to that.
What?
Where would the evolution take place?
The only thing that would change is the number of people being born with genetic medical conditions.
Without medicine these numbers would have been seriously reduced by the mortality rate of the sick not receiving medicine for their conditions, and therefore being unable to pass on their “inferior” genes back into the gene pool.
That is not evolution!
Evolution is not equivalent to progress; it is undirected.
If modern (or future) medicine renders a given previously-fatal illness non-fatal, then that will possibly result in that condition becoming more prevalent in the population (dependent, of course, on whether said condition affects reproductive success). So long as such medical care is available, that condition will not be deemed “unfit”, and thereby selected against. And that is evolution: natural selection only works for the here and now, not for any future benefit, and it does not work toward the good of the species.
If medical care is removed from an individual’s environment then the particular condition which it treated will likely once again enter the realm of “unfit”, and possibly be selected against.