is modern medicine ruining evolution?

Is modern medicine hampering the process of evolution and natural selection? 200 years ago, if you were born with a birth defect or severe asthma or a physical deformity or something, odds were you weren’t making it to adulthood and thus adding your genes to the gene pool. Nowadays we have organ transplants and dialysis machines and whatnot, and a lot more people are surviving that would have died in the past. Shouldn’t this increase in evolutionarily “weaker” genes out there be slowing down the process of evolution? Isn’t modern medicine preventing natural selection from taking place?

This topic has been done multiple times in GD so you might want to do a search. But the short answer is “no”.

Modern medicine is now part of our environment. If a catastrophy knocked up back to the stone age, we’d still have all the genes we had back then to get us back here again. None of the “good genes” are being eliminated. The " " are there to indicated that there are no good/bad genes without reference to a particular environment.

Really? In what sort of environment is hemophilia beneficial?

A good chunk of the modern medicine that you mentioned such as dialysis, and also cardiac care, etc. typically takes place after individuals have reproduced. Therefore, it has no effect on evolution at all, since the genes have already been passed on.

John Mace:

I don’t understand that argument. Perhaps evolution will not stop, but won’t positive evolution grind to a halt? If a birth defect that would naturally result in death before age 5 is introduced in a mutation, but modern medicine can perform an operation to prevent that death, nothing is preventing the propagation of that bad gene into modern society.

In caveman days, the unlucky child would die before reproducing and thus prevent the spread of whatever mutation caused his death.

You are right, it does have an affect on evolution. People may say it doesn’t, but thats just wishful thinking. But whether or not its a negative can be argued. If we have treatments for the illnesses, we can treat them.

Of course its more complicated than that, and if we suffered something catastrophic as a civilization in the futured, those weakened genes could be a hinderance, perhaps even significant. Can’t really say, evolution works in long long terms.

If ‘that gene’ is allowed to be reproduced, then children who would otherwise not have existed might also need the same treatment. Is that so problematic?

I believe people owe it to themselves to do some background reading on evolution before allowing themselves to get too confused by it; this topic seems to be very misunderstood: there is no such thing as “positive” or “negative” evolution. Do search the archives - we weren’t kidding when we said this very question has been talked about many times; it’s all in there :slight_smile: .

Can you define “positive” evolution? Evolution is simply change. And the more genetic diversity that exists in a population, the better chance that population has to survive in a changing environment. We don’t know what the future environment will be, so we can’t (generally) pre-judge if a given mutation is “good or bad”. Big brains would be a “bad” trait if women didn’t evolve larger pelvises to give birth to big brained babies. Without the latter, the former would be a survival disadvantage.

Evolution works like this:

Try everything.
Kill whatever doesn’t work.

You can’t overlook the “try everything” step.

OTOH, one might argue that using stone tools allowed some early hominids to survive who might not have originally survived. Thus stone tools are like modern medicine in that it “altered” evolution. One error in that logic is that evolution has some sort of direction. It doesn’t. Evolution is all about change, and adaptation to a changing environment.

As for the hemophelia gene, you forget that genes come in allele pairs. Sometimes having only one copy of the “bad” allele is good. The famous cycle cell/malaria link should be familiar to most people. The benefit to the overall population of having many people with one allele outwieghs the disadvantage of having a few people with both alleles. I don’t know of an advantage that having the “bad” hemophelia allele gives a person, but it might well do so in certain environments. Who knows, it might make blood clots in the brain less likely. Or it might make female carriers more attractive in some way to males.

You also have to keep in mind that almost no genes control only one thing. The vast majority of genes interact with other genes, or even certain aspects of the environment, which makes the simplistic dichotomy of “good and bad” genes erroneous.

That would be sickle cell… :slight_smile:

It doesn’t have to be beneficial. All it has to be is neutral in a particular environment, and it will not be selected against. In a modern society, with adequate medical treatment, hemophila may be selectively neutral.

“Evolution” as has been said is not positive or negative. All “evolution” means, at the most basic level, is that there has been a change in the gene (allele) frequencies within a population.

Decreased selection against “deleterious” genes due to medical advances will over time cause their increase in the population. However, this process is apt to be very slow, because most deleterious genes are recessive, and hence were not exposed to selection at a very high rate anyway.

Doesn’t it take thousands of generatios for evolutionary changes to happen? These bad-gene-enabling modern medecines have anly been around for a few tens of generations at best, and most of them much les than that. Even if this is a problem, it’s a very long-term one. We won’t see the effect for thousands of years, and by that time we’ll probably have genetically engineered all the inherited illnesses out of our gene line, or be reproducing by cloning, or be extinct, or something.

One other thing to keep in mind. A key survival strategy for humans has been to use brainpower in a social setting. IOW, not just being smart, but being able to interact with other smart people and pool ideas. The person with a so-called “bad” gene like hemophelia may discover some new scientific phenomonon or invent some new technology.

Or, more morbidly, having a number of extremely sick individuals in our society might spur the invention of technologies that allow the rest of us so-called normal folks a better chance of survival. And just wait until we can do genetic engineering on a practical scale. Talk about altering “natural” evoltion… Whoo-boy!!

Don’t forget dental medicine!
Pearly whites is a major attraction point for a mate.

Let’s not forget that having medicine is a result of the evolution of our brains.

Also, access to medical care is not equally distributed. It varries from location and social class. So, those with access to better care (usually wealthier) are capeable of producing more offspring. This would suggest that medicine is guiding evolution to favor smarter and prettier people.

This would be true, if it were the only factor guiding evolution. The same folk with access to better medical care are the same folk who limit their reproduction.

AcidKid has a point about dentistry. It has been said that advances in dental care has done more to extend life expectency than anything (except prenatal care).

Y’know, in all these questions about whether medical science is “slowing down positive evolution” I see an old “friend”: the concept of degeneracy. The idea seems to be that just as a body that sits around comfortably eating junk food with no regular exertion or mental challenges grows fat, sickly and dull, an entire species can go that way if not subjected to a physically and intellectually challenging environment (and, often the philosophers add, good moral rules).

Doesn’t work that way. In the environment that exists TODAY in much (by no means all) of the world, many physical conditions are not meaningful from a survival POV. And that is neutral until and unless there is selective pressure against them.

Besides, for humans, technology has been “interfering” with evolution for ages already. Think about it: when one now-forgotten pack of hominids developed the “killer app” for a once-new technology called the Pointy Stick, suddenly some people who would have been eaten by the leopards in youth were living to the ripe old age of 30-something. Talk about altering the balance!

The science of medicine is, itself, one of the results of human evolution, as are all activities of the mind. And, yes, some people with congenital “defects” can now live long enough to reproduce - and also long enough to become productive human beings, rather than sickly, dying kids. And maybe one of these people - or their descendents - will discover a cure for that defect, thus accelerating our species’ evolution.

Remember that it’s only relatively recently that great numbers of people are living long enough to have a real impact on the world. Previously, anyone with any impairment became a burden to his family or society; nowadays - thanks in part to modern medicine - most people live long enough to do more with their lives than simply produce offspring.

In the case of hemophilia, they are finding that there are more cases of hemophilia today because those that would have died 200 years ago are reproducing today, and having children who are passing it on to the next generation.

200 years ago, many tens of thousands of teenagers per year weren’t dying as a result of automobile accidents, either. Get back to me in a few million years; then we can talk about how much of an effect medicine may have had on our evolution. 200 years is nothing.

In the long run, I wouldn’t be surprised is for every “woulda-died” that gets saved as result of modern medicine, another “wouldn’ta-died” is killed as result of modern technology or lifestyle. The environment in which humans find themselves has simply changed relative to that of our ancestors, resulting in different selective pressures. That is neither good nor bad, and evolutionary mechanisms do not make the distinction.

Besides which, natural selection is not a guarantee that all that which is detrimental is removed, while all that which is not survives (and it is certainly no guarantee one way or the other for any given individual). It is a statistical phenomenon, acting over the whole of the population, and as such still very much holds sway.

Depends on the disorder. Cystic fibrosis, for instance, used to pretty reliably kill affected children in infancy or toddlerhood, long before reproductive age. Now, many are living into their 30’s. But they aren’t passing the gene on to anyone - CF causes sterility in men (I haven’t heard about the women) so even if they survive to adulthood, from evolution’s viewpoint they’re a dead end.

Being a carrier of CF, however, might make one more resistant to diarrhea-type diseases, diseases that used to be major killers everywhere, and still are in many places. That’s what has kept the gene in the gene-pool - if you get a half-dose you’re more likely to survive dysentery.

And, I know it’s been said already, but there’s *no such thing as “positive” evolution". * “Fit” in the sense of evolution means “leaves behind offspring, which leave behind offspring”. By this reckoning, Stephen Hawking is evolutionarially a fit individual while a childless Olympic athlete is not.

It’s all about how you fit into a given environment. The same genes that allowed the Pima tribe to survive in a harsh desert environment where food was scare are now killing them in an environment where food is plentiful (The arguably have the world’s highest rate of obesity, diabetes, heart disease, and related disorders). I myself seem to do well where food is plentiful - but put me into the Pima environment of 200 years ago I’d probably starve, or at least be very weak and ill, while they would do just fine, even thrive. Who’s the most fit? Depends on context.

Lifespan also makes a difference. When the human lifespan averaged 35-40 years, having the gene for Huntington’s disease didn’t matter much - it usually kicks in during the 40’s, so you’d have reproduced and died of something else before it could affect you. NOW, though, with life expectancy reaching into the 70s or 80s, and the ability to determine who carries the gene and who doesn’t, it can have an enormous affect. Some people voluntarially choose not to reproduce, for instance. A person who is known to have a relative with Huntington’s might find it hard to find someone willing to have children with him or her. Suddenly, what was “invisible” to selection is now very visible.

It doesn’t matter what the environment was two million years ago - what matters is the environment today.