Genetics, survival of the weak and the future of humanity

[F. King Daniel]

"Survival of the fittest" governed human evolution for thousands of years. Now, technology and medicine means that many of those with defects or disabilities, who would have probably died before, get to live normal lives and procreate. This is great news for them (including me - I'm blind as a bat without my glasses and that's just for starters!) but what does it mean for future generations?

The "bad" genes are now still in the pool. We're passing on our defects, and they're gonna mount up down the line. Or am I missing something?

 

[tau136]

"Survival of the fittest" governed human evolution for thousands of years. Now, technology and medicine means that many of those with defects or disabilities, who would have probably died before, get to live normal lives and procreate. This is great news for them but what does it mean for future generations?

The "bad" genes are now still in the pool. We're passing on our defects, and they're gonna mount up down the line. Or am I missing something?

Though not a fan of PC speak differently abled hits the mark here. Neither defect nor bad gene is any way to think about people who are not 100% A1 fit; that's the majority of the population of the earth anyway. It is as faulty a way of thinking as to say that if you don't have the body of a supermodel you are a superfluous part of the population.

Who can possibly judge what is or is not a desirable trait? In the Middle Ages survival of the fittest favoured the sword swinging strongmen right up until the rise of the mercantile class who used their business acumen to end up de facto rulers of society.

 

[MeanJoePhaser]

Why does the future of humanity matter? We'll all be dead.

 

[stj]

It's hard to get reliable figures, but the unfit who cannot survive to term apparently number from 50% to 80% of conceptions. Compared to that winnowing, natural and sexual selection of the people who make it out of the womb is almost certainly minor at most, possibly even trivial.

Fitness can be objectively measured but only in a particular context. For example, you can make a series of measurements to relate genes for superior dental health, leading to more grandmothers surviving because they can still eat tough foods, which increases survival of her grandchildren. But this is only significant in a technologically primitive society. You can measure the incidence of adult lactose tolerance but this is only significant in societies where milk is still a major nutrient. It just doesn't mean anything to talk about fitness in general. In general, the fit are those who reproduce which is tautological. (Tautologies are not false, but they are not often useful statements. Beware creationists who would have you believe that slipping into a tautology means an evolutionist is somehow wrong.)

As to specific diseases, the survival of individuals who make a contribution to society may increase the reproduction of other individuals. The Stephen Hawkings may in the end not just enrich our understanding but our technology. Natural selection works on the reproductive unit. People are not ants or bees but the individual is not quite the same as the reproductive unit. Even technologically primitive people, like American Indians or early pioneers did not send couples off to breed by themselves, they lived in groups.

Genetic engineering is much more likely to render such questions moot.

 

[TheKeeper]

"Survival of the fittest" has more to do with adaptability than with being the last one standing in a war of all upon all. In our case, our intelligence and opposable thumbs are just as natural an attribute as any other creature's strengths, but they give us the ability to accomodate ourselves to hostile environments and overcome weaknesses both individually and collectively.

 

[galleywest]

Humans as a species are fairly weak in terms of eyesight, hearing, and defensive capabilities, but we have thrived to be a dominant species. This is because we use culture as our method of adapting and surviving. We have highly developed social structures that have allowed us to survive far longer than our "natural" lifespan. We are also able to use our cultural adaptations to live and travel almost everywhere on our planet, to communicate (and therefore teach and pass on) highly complex ideas, and to make sophisticated tools that both help us live and connect with one another. "Fitness", then, in our case often looks very different from the traditional view of surviving in the wild.

So your eyesight is bad--for humans that's not the big deal it might be for a deer or a lion. We don't depend on it for survival because we have developed ways around it (I myself wear contacts). I'd be a lot more worried about being born without the ability to empathize with others (I mean, like a sociopath), because within our species that is extremely important for our survival and quality of life.

 

[Marten]

As long as cilization do not degrade, I don't think it matters that much.

 

[Robert Maxwell]

Technology will eventually take care of the vast majority of genetic defects, anyway, so I don't think it's a big deal. Natural selection only matters when your survival depends entirely on the genetic traits you've inherited. That hasn't applied to humans for quite some time now.

 

[Omnius]

I don't think it matters much. After all a disability doesn't mean you cannot contribute to society. For example just look at Dr. Stephen Hawking who has accomplished more in his lifetime than most fit people ever will or can only dream of.

 

[Kestra]

This might be totally irrelevant, but I wonder if there will be more interracial breeding which could counter some genetic issues. This is totally anecdotal, but for example, I'm a carrier of some blood disorder. If I had married an Indian, I'd be concerned that they were a carrier as well, but there's practically no chance that my husband is a carrier. Am I making any sense at all? I just know that there are some genetic diseases that are more common within certain ethnic groups for whatever reasons, and I wonder if some of that will go away with time.

 

[JonathonWally]

"Survival of the fittest" governed human evolution for thousands of years. Now, technology and medicine means that many of those with defects or disabilities, who would have probably died before, get to live normal lives and procreate. This is great news for them (including me - I'm blind as a bat without my glasses and that's just for starters!) but what does it mean for future generations?

The "bad" genes are now still in the pool. We're passing on our defects, and they're gonna mount up down the line. Or am I missing something?

As a species, we've reached a point in our evolution where we no longer have to adapt ourselves to survive our environments, we have the ability to adapt our environments to fit us.

It's pretty epic when you stop and think about it.

 

[melancholymecha]

Humans as a species are fairly weak in terms of eyesight, hearing, and defensive capabilities, but we have thrived to be a dominant species. This is because we use culture as our method of adapting and surviving. We have highly developed social structures that have allowed us to survive far longer than our "natural" lifespan. We are also able to use our cultural adaptations to live and travel almost everywhere on our planet, to communicate (and therefore teach and pass on) highly complex ideas, and to make sophisticated tools that both help us live and connect with one another. "Fitness", then, in our case often looks very different from the traditional view of surviving in the wild.

I wonder if other non human species will/could ever be capable of evolving "culture" and becoming as intelligent as humans have become...

 

[RJDiogenes]

This has been known to doctors and scientists for quite some time-- it's sometimes referred to as "medical evolution" or "medical selection." Basically, conditions that once might have killed someone before they had a chance to reproduce (or made it unlikely for them to carry a baby to term) are now treatable. So that means that while more people and babies are surviving, the genes for diabetes, heart disease and many other conditions are slowly becoming more prevalent throughout the population. The only solution to this, of course-- aside from abandoning medicine or practicing eugenics-- is more advanced medicine that actually cures genetic defects, rather than treating the symptoms.

This might be totally irrelevant, but I wonder if there will be more interracial breeding which could counter some genetic issues. This is totally anecdotal, but for example, I'm a carrier of some blood disorder. If I had married an Indian, I'd be concerned that they were a carrier as well, but there's practically no chance that my husband is a carrier. Am I making any sense at all? I just know that there are some genetic diseases that are more common within certain ethnic groups for whatever reasons, and I wonder if some of that will go away with time.

This is absolutely true. Interbreeding between distinct populations can dilute genetic disorders. The Royal Family might have less of a problem with hemophilia if they got out more. It can work both ways, though. Sickle Cell Disease used to be associated almost entirely with Blacks; now it is far less uncommon to find it in Whites as the "racial" barriers have broken down in recent decades.

 

[Goliath]

"Survival of the fittest" governed human evolution for thousands of years. Now, technology and medicine means that many of those with defects or disabilities, who would have probably died before, get to live normal lives and procreate. This is great news for them (including me - I'm blind as a bat without my glasses and that's just for starters!) but what does it mean for future generations?

The "bad" genes are now still in the pool. We're passing on our defects, and they're gonna mount up down the line. Or am I missing something?

I think you need to take a somewhat broader view of this question.

Natural selection, as I understand it, favours those organisms that are best adapted to their environment. The Great White Shark essentially stopped evolving a long time ago, because it was perfectly adapted to its environment, which remained unchanged--until humans came along.

As other people have mentioned, the sorts of traits you mention, like near-sightedness, are only disadvantageous in certain environments. Environments without eyeglasses, for example. So long as we don't lose the knowledge and ability to grind corrective lenses, there is no selection in favour of those with strong eyesight.

There is, however, selection in favour of those who are best adapted to civilization (in its broadest sense). For example: once we started herding animals, those of us who could tolerate lactose and consume animal milk had an advantage over those of us who couldn't. As a result, we have been evolving to become lactose-tolerant, and the ability to drink milk and eat things like cheese has been spreading, over time.

Like other animals, we are now evolving under the pressure of our own built-up artifical environment. Certain animals with certain advantageous traits (like cockroaches and rats and coyotes) flourish in this environment; others do not. Assuming that civilization doesn't fall off the Olduvai Cliff, traits that facilitate living in civilized societies should become more common over time, and should compensate for the increasing prevalence of traits like near-sightedness.

Bottom line: the fittest are still surviving--only the fitness test has changed. In the future, everyone will be a near-sighted computer nerd. And the opposite sex will find nerdiness hot.

 

[iguana_tonante]

There is, however, selection in favour of those who are best adapted to civilization (in its broadest sense). [...]

Assuming that civilization doesn't fall off the Olduvai Cliff, traits that facilitate living in civilized societies should become more common over time, and should compensate for the increasing prevalence of traits like near-sightedness.

That's a very interesting point. Beside lactore-tolerance, what do you (or others) think those traits will be? I'm think more about social behaviours than physical traits, but every idea is welcome.

In the future, everyone will be a near-sighted computer nerd. And the opposite sex will find nerdiness hot.

It has already begun.

 

[Nerys Ghemor]

"Survival of the fittest" governed human evolution for thousands of years. Now, technology and medicine means that many of those with defects or disabilities, who would have probably died before, get to live normal lives and procreate. This is great news for them (including me - I'm blind as a bat without my glasses and that's just for starters!) but what does it mean for future generations?

The "bad" genes are now still in the pool. We're passing on our defects, and they're gonna mount up down the line. Or am I missing something?

It seems to me that the difference now is that while some traits may have been maladaptive in nature, their effect is negated by medical treatment and hence in a strictly natural sense, they are no longer maladaptive (unless something destroys our technology). For some differences, I think that our technological abilities means that their usefulness and positive sides are able to come out and they are actually adaptive in certain arenas.

 

[Goliath]

That's a very interesting point. Beside lactore-tolerance, what do you (or others) think those traits will be? I'm think more about social behaviours than physical traits, but every idea is welcome.

*Scratches head*

I honestly don't know.

 

[sojourner]

In a million years will we have switched to a base 8 counting system because we no longer have pinky fingers?

 

[tau136]

There is, however, selection in favour of those who are best adapted to civilization (in its broadest sense)

That's a very interesting point. Beside lactore-tolerance, what do you (or others) think those traits will be? I'm think more about social behaviours than physical traits, but every idea is welcome.

Better tolerance of crowd noise; noiseyness & crowdedness.

 

[stj]

Natural selection in humans is still fairly intense in utero. There are no genes for individual or social behaviors being selected there. The importance of natural selection is proportional to its intensity. Every indication is that natural selection for behavior is minor, even trivial.

Further, behavior in human beings is so removed from direct genetics that humans cannot even be relied upon to mate properly. Quite aside from common non-reproductive behaviors, such as celibacy and homosexuality, there are a bewildering variety of paraphilias. I suspect that intelligence itself is the oppositie of genetically determined behaviors, so that the more you have of the one, the less you have of the other. There are documented cases of couples from earlier eras unable to consummate the marriage because of ignorance. The intensity of natural is proportional to the heritability of the trait selected. Every indication is that very little, if any significant, human behavior is heritable.

Last, the intensity of natural selection is proportional to the amount of variation. It is not at all certain there is that much variation in human beings. Consider one kind of behavior, sleep and dreaming. There seems to be no difference in human populations at all. And within the human population there seems to be a fairly small variance (I suppose a statistician would say there was a small standard deviation for the Gaussian distribution.)

This last is the most contentious. But scientists are still people, influenced by racial and religious bigotry, as well as conservatism, the perennial philosophy. Exaggerating genetic differences as a justification for the current social order (Social Darwinism, in other words,) is an easy trap to fall into.