6 ms·

* Analysis of 215,000 people's DNA suggests variants that shorten life are being selected against. * tested more than 8 million common mutations, and found two

* Analysis of 215,000 people's DNA suggests variants that shorten life are being selected against. * tested more than 8 million common mutations, and found two that seemed to become less prevalent with age. A variant of the APOE gene, which is strongly linked to Alzheimer’s disease, was rarely found in women over 70. And a mutation in the CHRNA3 gene associated with heavy smoking in men petered out in the population starting in middle age. People without these mutations have a survival edge and are more likely to live longer, the researchers suggest. * certain groups of genetic mutations, which individually would not have a measurable effect but together accounted for health threats, appeared less often in people who were expected to have long lifespans than in those who weren't. These included predispositions to asthma, high body mass index and high cholesterol. * Most surprising, however, was the finding that sets of mutations that delay puberty and childbearing are more prevalent in long-lived people.

deleted 9y ago
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mannykannot 9y ago
This puzzled me, as these Alzeheimer's and smoking results do not seem to be evidence of evolution; one would surely need to see a decrease over generations? The article goes on to say 'That such a large study found only two [late-acting genes] strongly suggests that evolution is “weeding” them out, says Mostafavi, and that others have probably already been purged from the population by natural selection.' The article and paper then repeat some hypotheses as to why natural selection would eliminate these hypothesized former late-acting genes from the gene pool, given that they seem to act after most people's reproductive years. So the article and paper seem to be arguing that a low frequency of late-acting genes indicates ongoing evolution, but acknowledge that this raises questions about why natural selection would act on them. The relevance of the decrease of the prevalence of these genes with age is apparently that survivorship bias is being used to distinguish causation from mere correlation.
- perlgeek 9y ago
  I had the same reaction as you at first, but read carefully: "Mostafavi and his colleagues tested more than 8 million common mutations, and found two that seemed to become less prevalent with age" Old people are less likely to have this gene than young people. This can have two possible explanations: old people with this gene are more likely to are already dead (and thus not show up in the study), or the gene is becoming more prevalent in the younger generations. The statement "People without these mutations have a survival edge and are more likely to live longer" favors the first explanation. This is not the effect of natural selection on gene prevalence. (And it would be weird for Alzheimer's, which usually occurs at an age where reproduction is often finished, and maybe even raising the kids is done already).
  - mannykannot 9y ago
    My apologies for editing my reply to add a third paragraph while you were replying to it, but I think that explains the relevance of the age dependence to this study: the decrease in the prevalence with age suggests that they actually do exacerbate the diseases they are associated with, and so the association is not merely a correlation. Note that they are not suggesting these genes have been the subject of selection; it is the hypothesized number of such late-acting genes that were not found that are assumed to have been selected against.
- memeCrasher 9y ago
  Could be that the genes have a deleterious effect in youth, not just old age.
  - mannykannot 9y ago
    That is one of the hypotheses advanced in the article.
  - AlexCoventry 9y ago
    Or it could be that aging is a complex process which a naive experiment like this is unlikely to shed much light on.
EGreg 9y ago
That last one may have a great deal to do with it. As people live longer and safer lives, they can afford to have children later. And child mortality has been seriously reduced, so the children they have are comparable to thise among people from previous centuries who had many children younger. Having children takes a toll on an organism, and having many children takes a larger toll, presumably. I wouldn't be surprised if there is a correlation between lifespan and number of children, among women. So - people live longer and have children later. The children grow up richer and bigger and in turn have children later, as well. I bet there is a correlation between age of having children and lifespan.
- tomerbd 9y ago
  there is i tell you ;) at least 20 years less off your life.
- glenstein 9y ago
  I definitely think postponing reproduction would coincide with longevity, but for a completely different/same-but-differently-stated reason. Evolution doesn't seem to care very much about the survival of an organism once they've successfully reproduced an optimal number of offspring, except to the extent that the organism can see to the well-being of offspring. It stands to reason that postponing reproduction for as long as reasonably possible would contribute to selection for longevity. From evolution's perspective, you have to survive at least that long, or else you're not good for anything. If humanity collectively decides to postpone having children, evolution may begrudgingly allocate more of its resources toward the welfare of individuals, rather than viewing our early deaths as an acceptable loss in a cold utilitarian calculation about long-term gene proliferation. (edits)
  - EGreg 9y ago
    Very interesting! I find this kind of line very exciting. But dows that mean some sort of Lamarckian evolution is taking place after all? Sexy son hypothesis is also similar. Is it related?
  - ForRealsies 9y ago
trophycase 9y ago
The last point isn't surprising at all. I think there is a subset of the population that matures quickly, reproduces quickly, and dies quickly. From my own observations in middle school and high school, those that mature earlier are far more likely to get into drugs, forgo education, etc... all things that are measures of success in our current society
- xtreme 9y ago
  Success in our society is not a good measure of evolutionary success. Evolution is only concerned about the number of viable offsprings you produce, not how well off they are.
  - wernercd 9y ago
    For reference, see Idiocracy opening sequence... https://www.youtube.com/watch?v=YwZ0ZUy7P3E https://www.youtube.com/watch?v=YwZ0ZUy7P3E Smart people delay, wait and then end up not... "dumb" people just hook up and go to town... I think the fact that Evolution is still spreading "successful" genes and "unsuccessful" genes become less prevalent is obvious. What isn't obvious, is as Idiocracy so succinctly puts it, is that gene that are "successful" doesn't necessarily translate to intelligence, good decisions, stable lifestyle, etc.
    - robotresearcher 9y ago
      That successful genes spread is a tautology. The frequency of a gene in a population compared to its alleles is its success. I wish we could retire the idea of success in an evolution and just talk about gene frequency. Then the irrelevant ideas of goodness and progress don't come up so readily in people's minds.

deleted 9y ago

[deleted]

mannykannot 9y ago

This puzzled me, as these Alzeheimer's and smoking results do not seem to be evidence of evolution; one would surely need to see a decrease over generations? The article goes on to say 'That such a large study found only two [late-acting genes] strongly suggests that evolution is “weeding” them out, says Mostafavi, and that others have probably already been purged from the population by natural selection.' The article and paper then repeat some hypotheses as to why natural selection would eliminate these hypothesized former late-acting genes from the gene pool, given that they seem to act after most people's reproductive years. So the article and paper seem to be arguing that a low frequency of late-acting genes indicates ongoing evolution, but acknowledge that this raises questions about why natural selection would act on them. The relevance of the decrease of the prevalence of these genes with age is apparently that survivorship bias is being used to distinguish causation from mere correlation.

perlgeek 9y ago
I had the same reaction as you at first, but read carefully: "Mostafavi and his colleagues tested more than 8 million common mutations, and found two that seemed to become less prevalent with age" Old people are less likely to have this gene than young people. This can have two possible explanations: old people with this gene are more likely to are already dead (and thus not show up in the study), or the gene is becoming more prevalent in the younger generations. The statement "People without these mutations have a survival edge and are more likely to live longer" favors the first explanation. This is not the effect of natural selection on gene prevalence. (And it would be weird for Alzheimer's, which usually occurs at an age where reproduction is often finished, and maybe even raising the kids is done already).
- mannykannot 9y ago
  My apologies for editing my reply to add a third paragraph while you were replying to it, but I think that explains the relevance of the age dependence to this study: the decrease in the prevalence with age suggests that they actually do exacerbate the diseases they are associated with, and so the association is not merely a correlation. Note that they are not suggesting these genes have been the subject of selection; it is the hypothesized number of such late-acting genes that were not found that are assumed to have been selected against.
memeCrasher 9y ago
Could be that the genes have a deleterious effect in youth, not just old age.
- mannykannot 9y ago
  That is one of the hypotheses advanced in the article.
- AlexCoventry 9y ago
  Or it could be that aging is a complex process which a naive experiment like this is unlikely to shed much light on.

EGreg 9y ago

That last one may have a great deal to do with it. As people live longer and safer lives, they can afford to have children later. And child mortality has been seriously reduced, so the children they have are comparable to thise among people from previous centuries who had many children younger. Having children takes a toll on an organism, and having many children takes a larger toll, presumably. I wouldn't be surprised if there is a correlation between lifespan and number of children, among women. So - people live longer and have children later. The children grow up richer and bigger and in turn have children later, as well. I bet there is a correlation between age of having children and lifespan.

tomerbd 9y ago
there is i tell you ;) at least 20 years less off your life.
glenstein 9y ago
I definitely think postponing reproduction would coincide with longevity, but for a completely different/same-but-differently-stated reason. Evolution doesn't seem to care very much about the survival of an organism once they've successfully reproduced an optimal number of offspring, except to the extent that the organism can see to the well-being of offspring. It stands to reason that postponing reproduction for as long as reasonably possible would contribute to selection for longevity. From evolution's perspective, you have to survive at least that long, or else you're not good for anything. If humanity collectively decides to postpone having children, evolution may begrudgingly allocate more of its resources toward the welfare of individuals, rather than viewing our early deaths as an acceptable loss in a cold utilitarian calculation about long-term gene proliferation. (edits)
- EGreg 9y ago
  Very interesting! I find this kind of line very exciting. But dows that mean some sort of Lamarckian evolution is taking place after all? Sexy son hypothesis is also similar. Is it related?
- ForRealsies 9y ago

trophycase 9y ago

The last point isn't surprising at all. I think there is a subset of the population that matures quickly, reproduces quickly, and dies quickly. From my own observations in middle school and high school, those that mature earlier are far more likely to get into drugs, forgo education, etc... all things that are measures of success in our current society

xtreme 9y ago
Success in our society is not a good measure of evolutionary success. Evolution is only concerned about the number of viable offsprings you produce, not how well off they are.
- wernercd 9y ago
  For reference, see Idiocracy opening sequence... https://www.youtube.com/watch?v=YwZ0ZUy7P3E https://www.youtube.com/watch?v=YwZ0ZUy7P3E Smart people delay, wait and then end up not... "dumb" people just hook up and go to town... I think the fact that Evolution is still spreading "successful" genes and "unsuccessful" genes become less prevalent is obvious. What isn't obvious, is as Idiocracy so succinctly puts it, is that gene that are "successful" doesn't necessarily translate to intelligence, good decisions, stable lifestyle, etc.
  - robotresearcher 9y ago
    That successful genes spread is a tautology. The frequency of a gene in a population compared to its alleles is its success. I wish we could retire the idea of success in an evolution and just talk about gene frequency. Then the irrelevant ideas of goodness and progress don't come up so readily in people's minds.