6 ms·

It seems to me that natural selection is, for the most part, broken now for humans. Intelligence and other positive characteristics don't seem to get involved

by unoti 14y ago

It seems to me that natural selection is, for the most part, broken now for humans. Intelligence and other positive characteristics don't seem to get involved in whether they have surviving offspring today the way I imagine it did a few thousand years ago. Is it true that natural selection for humans is mostly dead? Perhaps I'm wrong about this, but it's something that interests and concerns me.

pyre 14y ago
Just because Natural Selection(tm) isn't selecting for attributes that you regard as important doesn't mean it's dead. What it takes to have a better chance of survival now might be different than it was decades/centuries/millennia ago. If "having what it takes to climb the corporate ladder" is what gives your offspring a better chance of survival, then that is what is being selected for.
- potatolicious 14y ago
  "Survival" in the evolutionary sense is not "survival" in the social sense. Natural selection only works if unfit individuals are killed off prior to breeding. I don't think it's a stretch to say that, even in the least developed areas of the world, this is no longer the general case. Humans are no longer subject to natural selection, since nearly everyone survives to breed.
  - pyre 14y ago
    > Natural selection only works if unfit individuals > are killed off prior to breeding. > since nearly everyone survives to breed. No one needs to be killed off for natural selection to work. If they have some attribute that prevents them from finding a mate, that is also natural selection at work.
    - shard 14y ago
      Right, in other words, they are killed off by old age prior to breeding.
  - Scriptor 14y ago
    Even if everyone survives long enough to have children, that doesn't mean they all have equal numbers of children.
  - lotharbot 14y ago
    Natural selection doesn't require death, it just requires different reproduction rates based on genetics. Natural selection works strongly when group A dies before reproducing and group B does not. It still works, though more weakly, when group A has an average of 2.0 offspring and group B has an average of 2.1 offspring. In some parts of the world, natural selection is still significant (the common example: sickle cell anemia drastically increases malaria survival). In many parts of the world, though, differential reproduction appears to be a result of culture / religion / personal choice; it's not well understood how much this relates to genetics, and therefore not clear how much it deserves to be called "natural selection".
  - baddox 14y ago
    > Natural selection only works if unfit individuals are killed off prior to breeding. That's not true. Even in the hypothetical scenario that all humans reproduced exactly enough to replace themselves then died immediately (i.e. a completely constant human population), there would almost certainly be gradual change in the inheritable traits of the human population (i.e. evolution). If sexual partners are chosen, and those choices are inheritable traits (i.e. genes influence your choice of mate), that's textbook natural selection. > even in the least developed areas of the world, this is no longer the general case. A very large portion of the most successful pride of lions probably also breed, since they're not worrying as much about food or predators. Does that means the entire species is not evolving?
    - lotharbot 14y ago
      If genes change in proportion because they make people more or less likely to reproduce, that's "natural selection". If the genes change in proportion just due to randomness (they're all equally fit, but some were passed on more times than others as a fluke), we call it "genetic drift" [0]. Evolution involves mutation and gene flow [1] adding new genes to a population, and natural selection and genetic drift changing the relative proportion of various genes within the population. [0] http://en.wikipedia.org/wiki/Genetic_drift http://en.wikipedia.org/wiki/Genetic_drift [1] http://en.wikipedia.org/wiki/Gene_flow http://en.wikipedia.org/wiki/Gene_flow
      - baddox 14y ago
        I didn't mention any changes due to random sampling. I was careful to qualify that the choice of mate is influenced by genes. Wouldn't that qualify as natural selection more than genetic drift? Although, now that I think of it, the two are probably more like directions on a continuum, since choice of mate would be influenced by both genes and random sampling. Is that accurate?
        lotharbot 14y ago
        If choice of mate is influenced by genes, and there's a difference in fitness level due to those genes, then it would be natural selection. That is, if Alice-Bob have more kids than Claire-Dave for genetic reasons, natural selection is favoring AB over CD. If choice of mate is influenced by genes, but there's no difference in fitness level, then you're looking at a natural drift scenario. That is, if Alice-Bob have more kids than Claire-Dave due to some random effect like happening to meet much earlier in life, AB's gains over CD are classified as drift. Both effects are usually present, but sometimes one is much more significant than the other.
maratd 14y ago
I can't stress enough how important it is to read Darwin's original work. Contemporary understanding of evolution outside of academia is deeply flawed. There are two forces at work in evolution. Natural selection (survival of the fittest) and sexual selection (reproduction of the sexiest). Out of the two, natural selection is by far the weaker force. > Intelligence and other positive characteristics don't seem to get involved in whether they have surviving offspring today the way I imagine it did a few thousand years ago. You're thinking very narrowly in the "survival of the fittest" mode. You're ignoring sexual selection entirely. It doesn't matter how hot, strong, or brilliant you are, if you have zero kids, from an evolutionary perspective ... it's the same as if you were killed and eaten by some wild animal. And, of course, the quality of your offspring matters as well and is determined by mate choice. There's plenty of evolutionary pressure around today. Actually, I would say it's far more extreme today than ever before, especially in our urban areas.
- Scriptor 14y ago
  It's rather odd when someone says natural selection is completely 'dead'. Do they think everyone in the world has an equal chance of finding a partner and has the same number of children? Of course not. Even to this day there are factors that determine whose genes are passed down more frequently than others. I can't stress this enough, but there is simply no goal for evolution. Up until relatively recently, it just so happened that larger brains and other features we consider 'human' have been beneficial. Even if it may not be a big factor now, don't decry it as evolution being 'dead', or even worse, that people are devolving. If certain genetic traits allow certain people to pass their genes down to more offspring then you have all you need. It's a very simple concept with major consequences.
  - seanmcdirmid 14y ago
    As parent informed us, mate selection is called "sexual selection" and is a force that complements, but is not the same, as "natural selection." It is good to know the name for that.
- tmh88j 14y ago
  >It doesn't matter how hot, strong, or brilliant you are, if you have zero kids, from an evolutionary perspective ... it's the same as if you were killed and eaten by some wild animal. I don't agree with that 100% (the same as just dying part), solely because of the technology and globalization that we currently live with. Even if you don't have children, by simply starting a business where you employ many people, you're essentially providing a means to life for others. If your business is successful, you will have brought life to others via work for possibly generations(which essentially means others can provide a life for themselves and their families). I know that's a bit of a reach, but it's probably true to a small extent, at least in first world countries. Hundreds of years ago, I completely agree with you. We live in a world where your work can potentially impact billions of people. Sure, you may not reproduce, but you may have enabled many others to do so.
azakai 14y ago
> Intelligence and other positive characteristics don't seem to get involved in whether they have surviving offspring today the way I imagine it did a few thousand years ago. Selection is always active. First, there is sexual selection, not just natural selection, and there is no reason to assume that is not important today. Second, as the article says, there is more genetic variety than before - we accumulated a lot of variation in recent millenia. That's the necessary foundation for selection. Finally, a quick look around shows that some people have more children than others. You mention "Intelligence and other positive characteristics", but the fact is, it isn't clear intelligence was ever more important than say brute strength/social skills/etc. in our evolutionary history, so the fact it isn't the main factor now says little. But there definitely are factors that do contribute to having more (thriving) children today, and we are selecting heavily for them, for better or for worse.
- nhaehnle 14y ago
  it isn't clear intelligence was ever more important than say brute strength/social skills/etc. in our evolutionary history The juxtaposition of intelligence vs. social skills is amusing given the Machiavellian Intelligence Hypothesis, which suggests that our general intelligence basically evolved precisely as a means to get ahead in the social games that are relevant for sexual selection. If you can reason abstractly about what some rival is going to do and examine the "game tree" of potential actions, that is surely an advantage both for sexual selection and, say, debugging or proving theorems.
baddox 14y ago
Why would natural selection be dead? I don't see why humans would be any more immune from natural selection than any other species. At the bare minimum, people still choose their mates (and some die without reproducing), so unless these choices are completely unaffected by genes they should be causing a gradual change in heritable traits among the human population.
- nooneelse 14y ago
  Indeed, and we are probably facing new selection pressures. Such as the propensity toward addictions to substances our ancestors would not have had (http://www.guardian.co.uk/society/2012/nov/28/painkiller-addiction-plague-united-states http://www.guardian.co.uk/society/2012/nov/28/painkiller-add...).
  - baddox 14y ago
    Not to mention the constant arms race with biological pathogens.
lindbergh 14y ago
At any rate, it seems evolution has shifted from an individual action, to a cultural (or, dare I say, a civilizational) action. And from a cosmic point of view, it makes a lot of sense.
jnhnum1 14y ago
One thing the article mentioned was that people are choosing not to have kids. In this case, it seems that there should be an extremely high selection pressure for people to be genetically more predisposed to want kids. And if this does evolve to be the case, then as long as technology does not make reproduction free (in economic terms, there is currently a finite "supply" - the number of fertile women in the world times one baby per year), then competition on other traits will begin to be more relevant. So while people are saying that evolution is "selecting for less intelligence", this may be a short-term effect in which we are first as a species shifting to stronger reproductive urges at the expense of general intelligence, and only then increasing intelligence in a way which doesn't allow philosophical objections to having children. But evolution is pretty complicated, and difficult to reason about. Other people have also mentioned the "selfish gene" effect, in which altruistic / kinship behavior can be good for a gene, but suboptimal for an individual. It's possible some weird effect like that is going on also.

by unoti 14y ago

pyre 14y ago

Just because Natural Selection(tm) isn't selecting for attributes that you regard as important doesn't mean it's dead. What it takes to have a better chance of survival now might be different than it was decades/centuries/millennia ago. If "having what it takes to climb the corporate ladder" is what gives your offspring a better chance of survival, then that is what is being selected for.

potatolicious 14y ago
"Survival" in the evolutionary sense is not "survival" in the social sense. Natural selection only works if unfit individuals are killed off prior to breeding. I don't think it's a stretch to say that, even in the least developed areas of the world, this is no longer the general case. Humans are no longer subject to natural selection, since nearly everyone survives to breed.
- pyre 14y ago
  > Natural selection only works if unfit individuals > are killed off prior to breeding. > since nearly everyone survives to breed. No one needs to be killed off for natural selection to work. If they have some attribute that prevents them from finding a mate, that is also natural selection at work.
  - shard 14y ago
    Right, in other words, they are killed off by old age prior to breeding.
- Scriptor 14y ago
  Even if everyone survives long enough to have children, that doesn't mean they all have equal numbers of children.
- lotharbot 14y ago
  Natural selection doesn't require death, it just requires different reproduction rates based on genetics. Natural selection works strongly when group A dies before reproducing and group B does not. It still works, though more weakly, when group A has an average of 2.0 offspring and group B has an average of 2.1 offspring. In some parts of the world, natural selection is still significant (the common example: sickle cell anemia drastically increases malaria survival). In many parts of the world, though, differential reproduction appears to be a result of culture / religion / personal choice; it's not well understood how much this relates to genetics, and therefore not clear how much it deserves to be called "natural selection".
- baddox 14y ago
  > Natural selection only works if unfit individuals are killed off prior to breeding. That's not true. Even in the hypothetical scenario that all humans reproduced exactly enough to replace themselves then died immediately (i.e. a completely constant human population), there would almost certainly be gradual change in the inheritable traits of the human population (i.e. evolution). If sexual partners are chosen, and those choices are inheritable traits (i.e. genes influence your choice of mate), that's textbook natural selection. > even in the least developed areas of the world, this is no longer the general case. A very large portion of the most successful pride of lions probably also breed, since they're not worrying as much about food or predators. Does that means the entire species is not evolving?
  - lotharbot 14y ago
    If genes change in proportion because they make people more or less likely to reproduce, that's "natural selection". If the genes change in proportion just due to randomness (they're all equally fit, but some were passed on more times than others as a fluke), we call it "genetic drift" [0]. Evolution involves mutation and gene flow [1] adding new genes to a population, and natural selection and genetic drift changing the relative proportion of various genes within the population. [0] http://en.wikipedia.org/wiki/Genetic_drift http://en.wikipedia.org/wiki/Genetic_drift [1] http://en.wikipedia.org/wiki/Gene_flow http://en.wikipedia.org/wiki/Gene_flow
    - baddox 14y ago
      I didn't mention any changes due to random sampling. I was careful to qualify that the choice of mate is influenced by genes. Wouldn't that qualify as natural selection more than genetic drift? Although, now that I think of it, the two are probably more like directions on a continuum, since choice of mate would be influenced by both genes and random sampling. Is that accurate?
      - lotharbot 14y ago
        If choice of mate is influenced by genes, and there's a difference in fitness level due to those genes, then it would be natural selection. That is, if Alice-Bob have more kids than Claire-Dave for genetic reasons, natural selection is favoring AB over CD. If choice of mate is influenced by genes, but there's no difference in fitness level, then you're looking at a natural drift scenario. That is, if Alice-Bob have more kids than Claire-Dave due to some random effect like happening to meet much earlier in life, AB's gains over CD are classified as drift. Both effects are usually present, but sometimes one is much more significant than the other.

maratd 14y ago

I can't stress enough how important it is to read Darwin's original work. Contemporary understanding of evolution outside of academia is deeply flawed. There are two forces at work in evolution. Natural selection (survival of the fittest) and sexual selection (reproduction of the sexiest). Out of the two, natural selection is by far the weaker force. > Intelligence and other positive characteristics don't seem to get involved in whether they have surviving offspring today the way I imagine it did a few thousand years ago. You're thinking very narrowly in the "survival of the fittest" mode. You're ignoring sexual selection entirely. It doesn't matter how hot, strong, or brilliant you are, if you have zero kids, from an evolutionary perspective ... it's the same as if you were killed and eaten by some wild animal. And, of course, the quality of your offspring matters as well and is determined by mate choice. There's plenty of evolutionary pressure around today. Actually, I would say it's far more extreme today than ever before, especially in our urban areas.

Scriptor 14y ago
It's rather odd when someone says natural selection is completely 'dead'. Do they think everyone in the world has an equal chance of finding a partner and has the same number of children? Of course not. Even to this day there are factors that determine whose genes are passed down more frequently than others. I can't stress this enough, but there is simply no goal for evolution. Up until relatively recently, it just so happened that larger brains and other features we consider 'human' have been beneficial. Even if it may not be a big factor now, don't decry it as evolution being 'dead', or even worse, that people are devolving. If certain genetic traits allow certain people to pass their genes down to more offspring then you have all you need. It's a very simple concept with major consequences.
- seanmcdirmid 14y ago
  As parent informed us, mate selection is called "sexual selection" and is a force that complements, but is not the same, as "natural selection." It is good to know the name for that.
tmh88j 14y ago
>It doesn't matter how hot, strong, or brilliant you are, if you have zero kids, from an evolutionary perspective ... it's the same as if you were killed and eaten by some wild animal. I don't agree with that 100% (the same as just dying part), solely because of the technology and globalization that we currently live with. Even if you don't have children, by simply starting a business where you employ many people, you're essentially providing a means to life for others. If your business is successful, you will have brought life to others via work for possibly generations(which essentially means others can provide a life for themselves and their families). I know that's a bit of a reach, but it's probably true to a small extent, at least in first world countries. Hundreds of years ago, I completely agree with you. We live in a world where your work can potentially impact billions of people. Sure, you may not reproduce, but you may have enabled many others to do so.

azakai 14y ago

> Intelligence and other positive characteristics don't seem to get involved in whether they have surviving offspring today the way I imagine it did a few thousand years ago. Selection is always active. First, there is sexual selection, not just natural selection, and there is no reason to assume that is not important today. Second, as the article says, there is more genetic variety than before - we accumulated a lot of variation in recent millenia. That's the necessary foundation for selection. Finally, a quick look around shows that some people have more children than others. You mention "Intelligence and other positive characteristics", but the fact is, it isn't clear intelligence was ever more important than say brute strength/social skills/etc. in our evolutionary history, so the fact it isn't the main factor now says little. But there definitely are factors that do contribute to having more (thriving) children today, and we are selecting heavily for them, for better or for worse.

nhaehnle 14y ago
it isn't clear intelligence was ever more important than say brute strength/social skills/etc. in our evolutionary history The juxtaposition of intelligence vs. social skills is amusing given the Machiavellian Intelligence Hypothesis, which suggests that our general intelligence basically evolved precisely as a means to get ahead in the social games that are relevant for sexual selection. If you can reason abstractly about what some rival is going to do and examine the "game tree" of potential actions, that is surely an advantage both for sexual selection and, say, debugging or proving theorems.

baddox 14y ago

Why would natural selection be dead? I don't see why humans would be any more immune from natural selection than any other species. At the bare minimum, people still choose their mates (and some die without reproducing), so unless these choices are completely unaffected by genes they should be causing a gradual change in heritable traits among the human population.

nooneelse 14y ago
Indeed, and we are probably facing new selection pressures. Such as the propensity toward addictions to substances our ancestors would not have had (http://www.guardian.co.uk/society/2012/nov/28/painkiller-addiction-plague-united-states http://www.guardian.co.uk/society/2012/nov/28/painkiller-add...).
- baddox 14y ago
  Not to mention the constant arms race with biological pathogens.

lindbergh 14y ago

At any rate, it seems evolution has shifted from an individual action, to a cultural (or, dare I say, a civilizational) action. And from a cosmic point of view, it makes a lot of sense.

jnhnum1 14y ago

One thing the article mentioned was that people are choosing not to have kids. In this case, it seems that there should be an extremely high selection pressure for people to be genetically more predisposed to want kids. And if this does evolve to be the case, then as long as technology does not make reproduction free (in economic terms, there is currently a finite "supply" - the number of fertile women in the world times one baby per year), then competition on other traits will begin to be more relevant. So while people are saying that evolution is "selecting for less intelligence", this may be a short-term effect in which we are first as a species shifting to stronger reproductive urges at the expense of general intelligence, and only then increasing intelligence in a way which doesn't allow philosophical objections to having children. But evolution is pretty complicated, and difficult to reason about. Other people have also mentioned the "selfish gene" effect, in which altruistic / kinship behavior can be good for a gene, but suboptimal for an individual. It's possible some weird effect like that is going on also.