I keep seeing statements like these… and they seem so silly. There’s nothing magical about evolution that keeps us from evaluating it as positive or negative, just like we do with all other things. And there’s certainly nothing magical about it that guarantees that the direction we’re currently evolving in will turn out to be useful (or even harmless) X years down the line. So it certainly seems possible to me that evolution can be bad.
We are not evoloving in any direction. That statement implies that you can predict what our species will be like in the future. I suppose if we knew everything about how genes work and knew what the future environment would be like, then we could talk about good or bad adaptations. But we don’t and so we can’t.
I wondered if I should have used the word evolution in my OP. You’re all arguing about positive/negative evolution. The last sentence of my OP is the real question I was asking.
As I see it, modern medicine is preventing the individuals who would have died out from dying out. It’s interfering with natural selection. The less adapted individuals are surviving to pass on their characteristics when they wouldn’t have in the past.
And another thing I was wondering about- everyone knows about those useless things in the back of your mouth called wisdom teeth. Like the appendix, leftovers from a time when we ate tree bark or something. I hear the species is slowly getting rid of them (the teeth, and the appendix, and also apparently the small toe). So. I have no wisdom teeth. Not that I’ve had them pulled. They’re not there. I got X-rays the last time I was at the dentist and the nurse asked me where I’d had my wisdom teeth pulled. Nowhere, because I certainly don’t remember that. And she was amazed, because she’d heard of cases where someone only had 2 or 3 wisdom teeth, but had never heard of someone not having any at all. So, does that make me more highly evolved than the rest of society? 
I doubt a few thousand years of medicine can have any effect on ‘evolution’, and if it did how would one measure that?
I think the OP logic is that ‘natural selection’ is being mucked up by saving people who should’ve died and thus allowing whatever gene mutations they may have to proliferate.
When you think about dog breeding, this may seem plausible, because there certainly have been breeds ‘created’ by years of careful animal husbandry (ie a gene mutation is selected and encouraged). But with humans, just think of what you’d have to do to encourage a ‘bad’ gene to proliferate.
The OP question, nonetheless, is and will be more pertinent when genetic engineering comes into its own in terms of human manipulation (see the recent Newsweek article on boy/girl baby selection).
Relatedly, I believe there are way too many babies born with defects that should be allowed to die, but that is purely an ethical question for GD.
I don’t think anyone will disagree that modern medecine is affecting the evolution of the human species. Technology in general is affecting human evolution.
It’s the words like “ruining”, “hampering”, “weaker”, “preventing”, “interfering” that are catching our attentions. These words all have negative connotations, implying you believe evolution should be moving us in some beneficial direction. Evolution just happens; species are always changing. Whether the results are beneficial or not depends on what the future environments our species will face.
If our species returns to a hunter-gatherer culture/technology, then yes, a lot of genes that are now surviving will suddenly become mal-adaptive. But we don’t know what our future conditions will be. Maybe some of those genes will be adaptive in some unforseeable future. We don’t know, so we avoid using terms with positive/negative connotations when describing evolution.
You are missing the point. The concepts “positive/negative” or “good/bad” have no relevance from a scientific point of view. These concepts are only applicable from the point of view of human ethics/morality/utility. You are quite correct that these words can be applied to the discussion of scientific issues; however, the question then becomes one for GD, not GQ.
Whether a given evolutionary trend is “beneficial” or not can only be evaluated within a particular context. Take for example a population of birds isolated on an island without predators. In this context, it is completely beneficial for them to lose the power of flight, since it is unnecessary to find food or evade predators, and individuals with atrophied wings save energy and avoid being blown out to sea. Of course, once humans arrive with a few cats, it’s bye-bye birdie.
Of course you can generate some future scenario under which reduced selection against certain genetic traits will be detrimental. However, these are necessarily speculative. I can postulate that in the future, the ozone layer will break down causing selection against people of European extraction, who lack sufficient melanin in their skin to shield against skin cancer. Therefore we should prevent such people from breeding, since they may possibly be maladapted at some point in the future.
I would like to see a cite for this, please.
Well, that is true inasmuch as medicine is not “natural”. But you’re making an artificial distinction between something like medicine and something as simple as a stone tool manufactured 2M yrs ago. Everything we do as a species alters what will happen to the species relative to what would happen if we didn’t do that particular thing. So what?
If you have no wisdom teeth it might make you differently evolved, but not more highly evolved. There is a common misunderstanding that one species is “more highly evolved” than another. The tree of life model impies this, but it is just an artificial construct we have imposed on the life of this planet. It tends to propogate the erroneous thinking that current species evolved from extant, “less evolved” species. It’s like saying humans evolved from chimps instead of saying humans and chimps evolved from an earlier species. Neither humans nor chimps are more evolved relative to the other. They have evolved differently.
Now, if you want to talk about some organismism being more complex than others, that might make sense. But again, complex does not equal “more evolved”.
As John Mace has pointed out, there is no such thing as “more highly evolved.”
One can use the term “more highly derived,” which indicates that a species is different in a greater number of traits from an ancestral form. By having fewer teeth than an average human, you would be more highly derived with respect to the common ancestor of humans/chimps than most humans or chimps. (In having lost a structure that was previously present, evolutionists in the past might have referred to you as “degenerate,” although this term is now out of favor exactly because its negative connotations.) However, someone who had been born with six fingers on each hand, or with four, would be just as highly derived (or, in your terms, “more highly evolved.”)
I would also point out that in terms of your OP, lack of wisdom teeth could be considered “negative.” Perhaps under future conditions those with a full set of teeth will be favored by evolution. Therefore, if you believe the OP, since it could detrimental to human evolution, someone with your genetic makeup should refrain from breeding. 
You must have missed my previous post. Natural seelction is not a guarantee of death for those who “wouldn’t have [survived] in the past”, nor is it a guarantee of life for those possessing “good” genes. Nor is it even a guarantee regarding the reproductive possibilites of those individuals (humans being very fickle when it comes to such things). It is a trend within the population, and not every human has access to the same levels of “modern medicine”. For every individual with a disease which is saved, others do die. Perhaps those that are saved, and subsequently reproduce, have other traits which turn out to be benficial, so “saving” those genes turns out to be a good thing. Recent computer models have shown that in some cases, a beneficial, and selectively advantageous, trait can indeed be derived from a formerly-detrimental one. Looking at the here-and-now is very short-sighted when it comes to evolution. And natural selection is not so simple as “bad traits are removed, good traits continue”.
No, it makes you vary from others. Evolution is not just about being different. Unless you can point out what selective pressures favor the absence of wisdom teeth, such a trait is as meaningful (and probably less so) to our evolution as the color of our hair or eyes. All of which assumes, of course, that your lack of wisdom teeth is genetic in the first place. If it is but a developmental anomaly, then it is pretty much irrelevant to evolution.
[lateral-thought]Medicine doesn’t automatically create less fit individuals because it also guves us the ability to remove the “bad” genes (or it will in a few years). For every evolutionary downside of science/knowledge/technology there is a corresponding upside.[/lateral-thought]
[hijack]Has anyone else noticed that kids these days are getting taller? I’ve been 188cm for 20 years and I used to be one of the tallest guys in the crowd. Now I’m having to look around people’s heads.[/hijack]
OK, so we seem to agree that modern medicine is affecting the evolution of the human species. And I do understand that “ruining”, “hampering” and “weaker” have negative connotations. Notice that when I used weaker, I put it in quotes. But to me, “preventing” and “interfering” don’t really connote anything negative (it’s their denotations that are negative). If we agree that modern medicine is affecting natural selection in that it doesn’t happen, or at least not as much as it used to, then I don’t see a problem with saying that modern medicine is preventing or interfering with natural selection. Do we agree that natural selection is not occurring the way it used to because of modern medicine? Because that’s what I was getting at.
Evolution never happens “the way it used to”. But it is always a result of a change in environment and medicine is part of our environment. It can’t be said to be ‘interfering’ in a way that climate ‘interferes’, or plate tectonics ‘interferes’.
And no evolution is ‘bad’, even from a strictly non-scientific point of view. Evolution is what got us here and what will, hopefully, keep us from vanishing. Evolution is a response to change when staying still is not an option. If we evolve big hideous gills on the sides of our faces that stink of fish that will not be ‘bad’. It will be what has kept us alive in an underwater planet.
I always suspect the whole trouble people have with understanding evolution is a fundamental human inability to appreciate what is good, valuable and desirable personally for themselves, and what is good, valuable and desirable for a species as a whole. But then, this fact equally plays a part in what drives evolution, so it couldn’t be any other way.
I didn’t realize that “evolution” and “natural selection” could be used interchangeably. I thought one meant the changing of a species, and the other is the process by which the species changes. Am I wrong?
I said natural selection isn’t happening the way it used to because of modern medicine. I understand that evolution can’t happen the way it used to.
It is theoretically possible that relaxed selection for certain traits could have increased the frequency of these traits in the human population. However, I think it is unlikely that this has actually yet occurred over the human population as a whole for the following reasons:
-
As I previously mentioned, most “detrimental” genetic traits (let’s say those that would have caused mortality before reproductive age before 20th Century advances in medicine) are recessive. Therefore, they were not exposed to very strong selection anyway. Having been exposed to one selection regime for many thousands of years, and then switching to reduced selection over the past century, isn’t going to have changed their frequency in the global population very much if at all.
-
Given the very large size of the global population, and the fact that a very large degree of mixing has gone on and is accelerating, it is very difficult for selection to have any effect anyway. Selection works best in very small, highly inbred populations.
-
The human population has been growing nearly exponentially over the past century. There are about 4 times more people now than there were in 1900. Most of that increase has been due to the control of infectious diseases. Much of the most recent increase has been poorer countries where treatment for genetic diseases (as opposed to infectious diseases - although I recognize that susceptability to infectious diseases has a genetic component) is often not available, meaning the selective regime against them is not too different than it was previously. Again, this suggests that any increase in “detrimental” genetic traits has probably been minimal across the global population taken as a whole.
In short, the overall selective regime for humanity as a whole has changed drastically in many different complex ways during the past century. But this is far too short a time to assess any possible effect on “human evolution” as a whole. In five or ten thousand years maybe we will be able to tell, assuming the global selective regime stays stable over that period of time - an extremely unlikely prospect.
You are correct
Modern medicine has changed the environment for humans who have access to it. That is true. And therefore, humans with access to modern medicine will have some different selective pressures than humans w/o access to it. A bigger change in the environment is caused by agriculture-- something the vast majority of people have access to.
That’s probably got more to do with environmental factors, such as nutrition, than with anything genetic. Historically, rural people were taller than urbanites, mostly because they ate better…
But these kids are all urban, and urban kids are generally eating worse than previously.