u/lukmly013 💾 (lemmy.sdf.org) @lemmy.sdf.org

1y ago

A bit of a weird question: Can modern medicine be a threat to humanity long-term by greatly reducing effects of natural selection?

OK, I hope my question doesn't get misunderstood, I can see how that could happen.
Just a product of overthinking.

Idea is that we can live fairly easily even with some diseases/disorders which could be-life threatening. Many of these are hereditary.
Since modern medicine increases our survival capabilities, the "weaker" individuals can also survive and have offsprings that could potentially inherit these weaknesses, and as this continues it could perhaps leave nearly all people suffering from such conditions further into future.

Does that sound like a realistic scenario? (Assuming we don't destroy ourselves along with the environment first...)

104 comments

Pretty much everyone here either misunderstands how evolution works, or is willfully ignoring it to push their viewpoint.
Humans at this point have very little evolutionary pressure from natural selection. We aren’t getting weaker, shorter, taller, or anything like that from natural selection because those traits aren’t killing people.
The main driving factors for human evolution are sexual selection, random mutation, and genetic drift. There are still some poorer areas disease may still play a not insignificant part, but even that is fairly minimal since people largely live to reproductive age.
Human evolution has been fairly stagnant for quite a while. The differences most people would notice are from changes in diet, environment, and other external forces. For natural selection to pressure evolution we would need to have a significant portion of the population sure before they are able to reproduce.
- In this age of contraception, it's more a matter of wanting to reproduce (and how often) rather than merely being able to. I can't shake off the impression that less educated people are reproducing at a way higher pace, producing many offspring of which in before times many would not have reached reproduction themselves, but now they do.
  
  You should watch the movie Idiocraty.
- Pretty much everyone here either misunderstands how evolution works, or is willfully ignoring it to push their viewpoint.
  Yes! Finally someone else who knows how...
  Humans at this point have very little evolutionary pressure from natural selection.
  Oh come on! Such a strong start but then you fell on your face. Natural selection is the differential survival and reproduction of individuals due to differences in phenotype. It never lets up. It's more about reproduction than staying alive. Natural selection is happening every time someone reproduces more than someone else.
  
  Natural selection isn’t the only thing at play though. That solely refers to the organism best adapted to the environment being more likely to survive and produce offspring. Essentially everyone in our population survives to be able to produce offspring.
  Sexual selection plays a much bigger part now. That isn’t someone being the most adapted to the environment, it’s someone being the most attractive to a mate. There are plenty of adaptations across nature that are maladaptive to survival, but are selected for regardless.
  Then there are random mutations and genetic drift. Those happen in every population. That is more just a matter of chance.
  We have found ways to adapt to our environment outside of evolution. So we no longer have a significant natural selection process.

Same question rephrased: Can seat belts be a threat to humanity long-term by greatly reducing the effects of natural selection? After all, stronger individuals are more likely to survive car crashes.
What about wood stoves? Surely the fittest individuals are able to handle the cold?
We removed ourselves from "natural selection" a long time ago.
- And yet, we have not, for these inventions are the Adaptations developed by other humans for the purpose of the propagation of genetics similar to their own
  
  I think we're in a more similar position to birds of paradise. Several species of birds that live in the south Pacific/Indian ocean islands/Australia kind of region, where the weather isn't particularly harsh, their food is abundant and there are no natural predators, so natural selection has given way to mate selection. Male birds of paradise are fancy as fuck with brightly colored burlesque plumage not because it's any help surviving their environment, but because the girl birds think it's sexy.
  I think our genus is in a similar position, but got there via a different route. Once the upright walking, hands having, brain thinking ape got dexterous and smart enough to build fire and cook food, there was a sort of bootstrapping period of becoming smart enough to do engineering, at which point we arrive at anatomically modern humans, and from there most physical changes have basically been "because it's sexy." Men have deeper voices because it turns women on. Women have permanent boobs because it turns men on, etc. People from Asia have distinctively shaped eyelids...is there some environmental pressure in Asia that doesn't exist in Europe or Africa, or is it because that eye shape became fashionable to ancient Asians?
  And now we've arrived in a time where we have a functioning understanding of how genetics work, and the ability to manipulate those genetics at industrial scales. Seriously I think we departed the "it was cold so the ones with thicker fur were more likely to survive to fuck another day" phase of existence at some point, with the invention of writing at the latest.

No. This is a result of thinking of natural selection as working towards an "absolute" better and away from an "absolute" weaker, as opposed to pushing in directions that are entirely defined by the situation.
Natural selection is this: in populations that make copies of themselves, and have mistakes in their copies, those mistakes that better fit the situation the copies find themselves in are more likely to be represented in that population later down the line.
Note that I didn't say, at any point, the phrase "SuRvIVaL oF ThE FiTtEsT." Those four words have done great harm in creating a perception that there's some absolute understanding of what's permanently, definitely, forever better, and natural selection was pushing us towards that. But no such thing is going on: a human may have been born smarter than everyone alive and with genes allowing them to live forever, but who died as a baby when Pompeii went off - too bad they didn't have lava protection. Evolution is only an observation that, statistically, mutations in reproduction that better fit the scenario a given population is in tend to stick around more than those that don't - and guess what? That's still happening, even to humans - it's just that with medical science, we're gaining more control of the scenario our population exists in.
Now, can we do things with medical science - or science in general - that hurts people? Sure, there's plenty of class action lawsuits where people sued because someone claimed their medicine was good and it turned out to be bad. But if you're asking "are we losing out on some 'absolute better' because we gained more control of the world we reproduce in," no, there is no "absolute" better. There's only "what's helpful in the current situation," and medicine lets us change the situation instead being forced to deal with a given situation, dying, and hoping one of our sibling mutated copies can cope.
- there's plenty of class action lawsuits where people sued because someone claimed their medicine was good and it turned out to be bad.
  It was only a couple of flipper babies…
- Survival of the fittest doesn't mean what you think it means. Fitness, in the evolutionary sense, is a quantitative representation of individual reproductive success. So yes, the fittest of us do survive in the sense that their genes are passed on far more often than those that are less fit. For example, the overweight, nearsighted, diabetic car salesman with a lethal peanut allergy that has 16 children is more fit than most people on the planet.

Plenty of answers already.
I'd like to point out that it's not medicine alone, but empathy that changes natural selection. We have evidence of our ancestors caring for members of their tribe that would have been unable to survive otherwise.
But while in some edge cases (some diseases) you could make an argument that it's bad for future humanity for some reason, it's overall good, because it enables a larger population. And a larger population has a better chance of mutating to fit changing environments. Or to phrase it differently: diversification comes first, selection can wait.
- Populations do not mutate. Mutations occur randomly within individuals, they do not occur to fit a changing environment, they only occur randomly. A mutation can spread through a population if nothing selects against it. Selection never waits, it's always there in one form or another.

Hmm, that's an interesting question. I'm not an evolutionary biologist but I am a biologist (more specifically, a microbiogist).
The crux of the misunderstanding, I think, is that the definition of what counts as advantageous or "good" has changed over time. Very rapidly, in fact. The reason many diseases are still around today is because many genetic diseases offered a very real advantage in the past. The example that is often given is malaria and sickle cell anemia. Sickle cell anemia gives resistance to malaria, which is why it's so prevalent in populations that historically have high incidence of malaria.
Natural selection doesn't improve anything, it just makes animals more fit for their exact, immediate situation. That also means that it is very possible (and in fact, very likely) that the traits that we today associate with health will become disadvantageous in the future.
If we remember that natural selection isn't trying to push humanity towards any goal, enlightenment, or good health, it becomes easier to acknowledge and accept that we can and should interfere with natural selection
- the traits that we today associate with health will become disadvantageous in the future.
  Yeah I can think of a few, like aging. 10000 years from now kids will be saying, "wow, those poor unevolved savages lived such short lives and only really got to enjoy the first little bit of it before they started falling apart. They even had genetic engineering at the time! Imagine how many people would be alive today if they hadn't been so scared to edit their genes to prevent aging." Then their teacher would come over and explain that it wasn't so easy at the time. There were still so many other problems they had to solve and related genes that need to be modified to avoid undesirable consequences, and let's get back on topic: how many planets fall under the rule of the galactic empire including our own planet Urth?

I feel like the largest threat may be C-sections over natural births. A lot of births in developed countries are C-sections, with a lot of it being because the babies are too large to fit comfortably through their mothers' hips.
As baby size increases and has benefits post birth, there may come a day where some human populations need to rely on C-sections to propagate.
- That wouldn't be a threat to humanity.
  
  It would be if we suddenly didn't have access to modern medicine for some reason. Like say a city under seige with power cut iff to hospitals
  
  It would be a threat to humanity's continued existence in the case of societal collapse. You know, the one we are in the middle of. If one generation cannot for any reason give birth to the next one. It is over. We are facing that scenario right now.
  The fact that sperm count in men is alarmingly poor all over the world. Be it caused by pollutants or by medicine allowing those unable to procreate naturally to pass on their genes.
  The "gender revolution" has allowed people to be what ever they want to be. But this has led to them to be unwilling or unable to procreate without advanced medicine.
  Birth rates are falling off a cliff around the world. In some countries the population will be halved by the end of the century given current birth rates.
  This will cause a societal collapse. And those unable to procreate without advanced medicine will die without having children. The others will face an uphill battle to continue living. Their weakened immune systems inherited from ancestors saved by medicine. Battling superbugs created by medicine. Without access to it.
  In an effort to heal and help medicine has weakened us and left us vulnerable. And that is a threat to humanity's continued existence.

The more varied the sample of individuals you can afford to keep alive in your population, the more chances you have that a subset of them will be able to withstand random changes in the fitness function. If the environment changes abruptly, you will have a hard time adapting as a species if you only ever supported people "within the norm". What happens in those cases is called extinction.

Oh boy, a population genetics question in the wild.
In technical terms what you are asking is:
When a selection pressure is removed for a deleterious allele, what happens to the allelic frequency on the population?
The answer: they remain stable in the population, unchanging from when the selection pressure was removed. Every generation will have the same ratio of affected individuals as the previous one
Look up Hardy-Weinberg Equilibrium for more info.
- Well that's interesting, thanks!
- Hardy-Weinberg isn't appropriate here. If all alleles were neutral, they'd get slowly lost or move toward fixation at a rate proportional to the mutation rate by genetic drift. In the absence of negative selection, new variants that are deleterious without modern medicine would do a random walk in allele frequency, meaning some would become prevalent. But the population is so large they would take far too long to be completely fixed.
  Hardy-Weinberg is a model that makes by true assumptions (like zero mutation rate and infinite, isolated populations).
  
  You seem to be lost in the weeds a bit. Of course hardy-weinberg is a model that never exists in reality. It's a good method to explain the importance of selection pressure on populations.
  Without an active selection agent on the allele, it's frequency in the population remains the same.
  Now in reality there is no such thing as zero selection pressure on any allele. Having a deleterious or advantageous allele 49.99cM away exerts selection pressure.
  However allelic frequencies without a strong selection acting on them remain relatively stable.

Yes absolutely. We've already affected our biology and evolution.
Birth control, antibiotics, are examples
Given time, and even greater lifespans, we will have a larger impact on the path of our evolution.
As a thought experiment let's imagine humans that live for 2,000 years. What does this mean for our adaptability to environmental changes? What does this mean for our fertility?
If nothing else changes, the carrying capacity for new humans will decrease, if the average lifespan goes up to 2,000 years.
From an evolutionary perspective, the question is always what is the current selection pressure? Historically it's almost always been intelligence plus something else, melanin in the skin, the ability to metabolize lactose into adulthood, etc...

Oh cool, it's time to find out how much of a burden on humanity I am and whether I should have been left to die. Just hypothetically of course, I wouldn't want anyone to misunderstand. I always enjoy this question with my morning coffee.
- realistically industrialization and guns have a far larger impact on human evolution rn than healthcare.
  
  Exactly, and yet the question is never "is agriculture a long-term threat to humanity?". It's always the people with medical issues who are acceptable first choices as society's sacrificial MacGuffin, long before we question any technology that benefits the person who is "just asking questions".
  It's like we didn't already do Social Darwinism the first time. Super frustrating.
- Maybe you should skip these threads in the future. Don't you think it's important for people to understand this concept? Not everyone knows everything. Educate.

I would argue that modern medicine prevents non-selective deaths. We try and keep everyone alive, not just the idiots.

Survival of the fittest just means the most adapted to the current environment. Our current environment has medicine so we're adapted to that. If that suddenly changes then sure it would be an issue, but so would a climate difference of even a few degrees, a slight difference in the chemical make up of air, etc.

i always thought that it was the greater volume of humans, the greater the genetic diversity
- There's barely any pressure to extinguish "bad" traits, though.
  If you're the idiot who eats every berry you can find, cavemen can't save you and your genes disappear. Modern medicine can and will save you, so you can create offspring and the berryeaters keep their proud heritage alive.
  Now, what is considered "good" or "bad" is of course highly debatable, but currently we have effectively no survival pressure, the only selection is how many children you get.
  
  But that if that "idiot" does propagate, but so does everyone else, no skin off the species back. If the selective pressure returns, well then the others keep going.
  
  OG Luci is right, though. There are far more people due to modern medicine. So if we suddenly lose it, there will be a lot of death. But there is more population and diversity to draw from the survivors. So I don't think it's a threat to the species.
  
  Well, that's a type of pressure. Ogg the berry lover could well have passed on his genes.
  For a long time we've largely been selecting for intelligence and social abilities.

Call me when evolution figures out how to deal with guns and automotive accidents, which likely represent the largest selection factors on modern humans.
- Actually education is probably the largest selection factor. Educated people have less children than less educated people. Sometimes massively so. This is not necessarily linked with intelligence, it correlates more with socio economic factors.
  
  The problem is that people don't seem to realize the difference between causes of deaths and population declination. Even if for some reason humans everywhere agree on The Purge like laws except for every day, that wouldn't represent a risk for humanity (as long as governments still withhold their nuclear arsenal), some cities might be all but wiped out, but the chances are humans will survive. Anarchy was the status quo for the vast majority of human existence, and we're still here.
  However other seemingly innocuous things are much worse for humanity as a whole, e.g. electing politicians who disregard climate change or that intend on using military power to take others territories can have much larger consequences on humanity as a whole. Your example is also great, because it's counter intuitive that higher education leads to population declination, that being said I believe that also wouldn't become an extinction event, surely the world would become a place where highly educated people want to have children before that.

Natural selection is an agent that runs contrary to the thing which is currently out-competing natural selection, that being big brain thinkering
E.g., if a cancer research scientist dies from a weak heart, that will reduce future life expectancy more than it will increase it
- Natural selection and evolution happen because genetic traits in some individuals are more beneficial than in other individuals. It has nothing to do with increasing future life expectancy for most or all of the species. If a doctor is helping non-relatives far more than relatives, his contribution is not selected for.
  
  a doctor is helping non-relatives far more than relatives, his contribution is not selected for.
  Which is the whole point of my comment...

I expect gene editing soon to become so cheap that everyone starts customising their children, resulting in a situation analogous to where dogs are now: extreme variability improving the chances for survival by making sure we have the needed people for any situation except gamma ray burst which requires backups far from Earth.
- I've been working on a sci Fi show where humans have this but they also have the ability to change their current physiology by infecting themselves with modified strains of cancer that slowly replaces you're body with one you downloaded off the Internet this technology has also sorta obsoleted medicine because if you have a broken leg or infected with a fatel desese so long as the injury doesn't affect your brain you can just replace your entire body by infecting yourself with genetically modified cancer

If genetic research gets to a point where we can beat any mutations, then probably not.

I can, will and has. Push back would be on what it means to be "weaker".
When we say evolution selects for strength, we mean strength in terms of environmental fitness with regards to propagation, not anything specific to health, well-being or survival.
Our earliest "medical" advances actually left us significantly less robust over time.
Techniques like "not leaving the sick or injured to die", "blankets", "carrying food and water" and things like that.
Over time, that led is to continue with bigger brains, longer gestation, more care for the mother and infant before and after birth, and old people.
This led to a spiral of smarter, more educated, more cared for people who were able to pass on knowledge between multiple generations.
None of that could have happened if we hadn't started caring for less robust people, like old man Greg with the bad leg, scary stories about snakes and knows all the berries, or Jane who is somehow so pregnant she can barely walk and who's last kid was born with a massive cone head and no kneecaps.
What makes us unique as a species is that we have a much larger ability to influence what exactly defines environmental fitness than others.
When we develop new medical treatments, we are potentially making ourselves less robust going forwards, but we're also making it so that particular thing has less weight in determining what "fitness" means for a human, and more weight is put on "clever" and "social".
Natural selection selected for a creature that can't opt out of the game, but can bump the table.
So we will inevitably allow a genetic condition that's currently awful to become benign and commonplace.
We'll also keep selecting for smart, funny, social and dump truck hips.
My biggest contenders are diabetes, gluten intolerance and hemophilia. They all used to be death sentences, and now they're just "not". There's also the interesting possibility of heritable genetic treatment becoming possible, which puts a lot of what I said into an interesting position.
We'll probably keep selecting for those big hips though.

The entire point of medicine is to give nature the finger. The goal is to make natural selection obsolete. We can certainly screw it up enough to wipe us out though or be unfair with it.

Yes, but I'd argue that capital has a more profound impact than "modern medicine".
There is a massive MASSIVE selection pressure against reproduction for if you can afford kids or not.
You can look around the world and see countries with amazing health outcomes, beyond anything our ancestors even a few generations back could have dreamed of...
... And yet these countries no longer even have children at a replacement rate.
I'm not saying medicine isn't a factor... Just saying that in terms of evolutionary pressure, capitalism is even greater a pressure.
- if you can afford kids or not.
  To amend that, if you are responsible and think you can't afford kids and have the restraint and planning to select not to have children.. there are plenty of people that can't afford as many children as they have.
  In fact of those that can "afford" kids easily, they are still more likely to stay at one or two.

A quite different approach: modern medical practice uses a whole lot of medicine, which ultimately ends up in (waste) water, and becomes an environmental problem, including a health hazard to humans. https://www.sciencedirect.com/science/article/pii/S2772427122000390

Also, a point I don't see others mentioning, is religious people often tend to have more children, and whilst religion isn't actually hereditary, children often do have more likelihood to follow the same religion as their parents, the population is likely to tend to more extremist religious people, unless the rate of conversion away from those religions drastically increases.
- Well, if that were the case wouldn't we expect to see near universal religious belief now?
  We can't start the population set now, we should look at when religion started.
  I'd posit that as time goes on, the religious beliefs tend to want to spread, but they also round off more difficult to wrangle aspects to maintain appeal to a wider audience. A belief system incompatible with observed reality or unpalatable to potential new believers is going to be less robust than one that fits and is welcoming.
  It's why today's extremists are generally more tame than the commonplace believers of the past.
  Eventually some people catch a version of the religion so weak that it's only kinda comparable, and you have the Christian who never goes to church or thinks about it really, or the person who's a vague notion of spiritual without much specific behind it beyond a vague notion of purposeful intention to the world.
  
  I'm not talking about converting new believers from outside, I'm talking about children inheriting the religion of their parents. And yes, in the places where religion has spread, only a small percentage of the population wasn't religious, and it's a relatively recent thing that a significant fraction of society isn't religious.
- Hopefully the inbreeding within those weirdo groups helps fix that.

I don't think so.
For one, natural selection selects the "fittest", but what the "fittest" means, changes over time.
Also, there's lots of other factors that you may have overlooked, such as sexual selection probably playing a bigger factor.

Natural selection led to our intelligence to be able to made medicine in the first place.

There are already lots of great answers, I would like to point out that Natural Selection doesn't care about the individual at all, it cares about the population, e.g. internal gestation, do you think any individual enjoys carrying a baby inside them? Preventing them from doing anything during the gestation period, being an easier prey to predators, etc... Unfortunately for the individual, creatures that carry their unborn babies inside them are less likely to abandon them even temporarily while seeking food, they're also more easily kept warm, so for the species as a whole it's better that there be internal gestation.
In short more individuals = better, imagine you have two populations, one with only 10 strong individuals, and one with 100 individuals of which only 10 are strong, which do you think is more likely to survive? And that is even assuming a strong/weak deterministic position, which is not the case for anything.

I would say that the greater the population (in part thanks to medicine) the greater the chances of beneficial mutations occurring and entering the collective gene pool. I see medicine as a safety net. I'm sure it's more complicated than that, but that's my professional take on it, as a musician.

Sexual selection usually takes care of problems like this. People with antisocial tendencies find it extremely difficult to find partners.
- Unfortunately, not when they have money.

No. Human evolution is driven primarily by mate selection.

It already has affected natural-selection.

I think you have a point. We are making ourselves dependent on our technology. There will come a time where the constant fight our bodies deliver against disease and defects cannot be maintained without the technology created as a consequence of our highly complex society. If we continue on our current trajectory there might come a point of no return. If you want to return to monke now's the time, I guess?

I think a bigger threat to humanity is a LACK of modern medicine. Both because denying people life-saving medicine because you think they're "weak" is inhumanly cruel, and because of that plague we just had.

I think we've already demolished natural selection over here, modern medicine being the least of concern. Idiocracy was supposed to be humor, not foretelling.

This has been happening for a while now and the results of which are the voting populace of the anti-intellectual movement that is explained in the documentary film, Idiocracy.
- Not necessarily the genes' fault:

natural selection does not choose whats best overall, just those that can reproduce. steinmetz was a hunchback cripple dwarf who was the actual intellectual powerhouse behind GE and responsible for much of our quality of life in the modern age.
- steinmetz was a hunchback cripple dwarf
  I never want to hear anyone say again that "nobody calls someone a 'cripple' anymore". Perhaps consider this somewhat less grotesque alternate phrasing: "Steinmetz was a person who experienced significant and debilitating disability".
  natural selection does not choose whats best overall, just those that can reproduce.
  That's not only an incorrect understanding of natural selection, i'd add that Steinmetz chose not to reproduce. If he hadn't been the topic of your next sentence, I wouldn't have felt the need to emphasise his personal agency. Or his existence as a person
  
  I know he chose to not have kids and the phrasing I used has been used with him in particular forever to emphasize the extreme challenges he had to deal with. Its great you like a certain more generic phrasing which could be applied to anyone.

Your question is actually a subset of:
"Can short-term-gain actually fatally undermine long-term-viability?"
I don't consider the question incorrect, at all.
Peter F. Drucker, in one of his books, has it that the "Health Care Industry" hired him,
and one of the 1st things he did, was..
told them, bluntly to their face, directly, approximately that
( this gets the gist of it, but this is from-memory, not exact/verbatim )
"You aren't the Health Care Industry, you are the Illness Care Industry, and you aren't fooling anybody, AND you aren't improving your credibility by speaking falsely"
Does taking all kinds of chemicals, so that one can be a "better bodybuilder", and then ending up in a population who dies significantly younger than average, due to heart-failures, be considered "good"??
Obviously, to the corporate-"persons" who make money having as much of the population addicted to that distortion as possible, YES!! PROFITS!!
Unfortunately, it isn't possible, in any political system, to get decisions made by correctness, accuracy, reason, objectivity, maximum-benefit-for-greatest-number-of-dimensions-of-the-population, etc..
The lobbies won't allow that.
Remember Covid?
Remember the people who were insisting that immunization was a scam, & that people should be relying on their body's innate robust immune-system?
These were people who consider yogic-living to be corruption, and heavy-meat-eating to be "good", nitrates in meats, & all.
The lobbies have overrun all discussion, not allowing objectivity to own any territory.
I think you are right, but the right-answer to it includes simultaneously improving the health of individuals, of entire-populations, AND getting people out immersed in nature more, so as to have built-up more-powerful immune-systems, in the 1st place!
Selectively extinguish some infectious-diseases ( I'd target rabies, ebola, HPV because it causes cervical cancer, & a few others, for extinguishment ), while dealing-with as many as we viably can,
in the hopes that "surprises" will not be able to trash/wreck our innate immune-systems, see?
_ /\ _

I’m sure you’ll be asking your first responder this question while he or she is in the middle of performing CPR on you, and calling for an AED, right? You’re not regretting the discovery of 30-2, are you?
- You did misunderstand the point of this question.
  Yes, I'd prefer not being resuscitated. If I am finally dead, let it stay that way.
  
  I don’t think I misunderstood. You see dropping dead as your prize for losing in some type of social Darwin competition. You don’t see medical advances and life saving measures as being part of our evolution, as a species, to better survive? No offense, but regardless of how you feel about being resuscitated, some paramedic, or other first responder is still going to try to save your life. They can’t exactly stop the process and ask you for your opinion if you have no pulse, dude.

104 comments