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The way the title is phrased is strange. To the young/uneducated reader (not so many around here, but still), it reads like humans evolve to develop a particula

The way the title is phrased is strange. To the young/uneducated reader (not so many around here, but still), it reads like humans evolve to develop a particular trait, when we know that people who developed that trait got an evolutionary advantage and ended up spreading their DNA more than others on average. Not as catchy a title, sure, but at least, it doesn't misrepresent the evolutionary process. NOTE: I am not an evolutionary biologist, so there is most likely an even better way to rephrase my rephrasing. I'd be glad for anyone to do so, the more accurate, the better.

posterboy 10y ago
> it reads like humans evolve to develop a particular trait, when we know that people who developed that trait got an people who developed that trait had to evolve to do so, no? Not as an entire population, but maybe over the live span of individuals. Maybe the smoke itself caused that, as exposure often does, "evolving" in some individuals who then pass immunity markers down over generations through blood in the womb rather than genetically. Or maybe the smoke is cancerous and caused beneficial mutations. I should read the paper (edit: it says genetic). All I'm trying to say is, either development is subsumed under evolution.
- inimino 10y ago
  > people who developed that trait had to evolve to do so, no? The word "evolve" in English means a gradual change, so no. Random genetic mutation isn't a response to the smoke, and there isn't anybody born unadapted who then adapts by exposure. The species evolves, individuals don't.
  - nonbel 10y ago
    >"The species evolves, individuals don't." You are made of cells that are many generations separated from the fertilized egg. I don't see why you accept evolution at the species level but not cell level. This sounds like a kind of reverse creationism, where macro-evolution is ok but micro-evolution is not.
    - inimino 10y ago
      Um, honestly not sure what you're getting at there. The individual cells in your body are genetically the same as what you started with, with occasional random mutations. The body defends itself against those mutations and most will be eliminated. Some will become cancers. They don't affect the DNA you pass on to your offspring and so aren't a part of the evolution of your species. None of them are going to give you superpowers unless you happen to be living in a comic book.
      - nonbel 10y ago
        Say a person is exposed to smoke often since being a young child. At some point, a lung cell is dividing and randomly gains a mutation that increases expression of some smoke-protective protein. This lung cell is then more fit (to the smokey environment) than the surrounding lung cells. As a result, its daughter cells will divide more often than the others and populate the tissue. Are you denying this can happen? Or is it that you do not consider that process to be evolution?
        alecmckinley 10y ago
        That absolutely can happen - but remember that the traits of the 'evolved' lung cell will not be passed to offspring, as the genetic makeup of gametes (sperm) is a random (50%) subset of the main genetic code.
        nonbel 10y ago
        Sure, but the population of cells we call an individual human being does "evolve" over the course of its life.
        logfromblammo 10y ago
        The vast majority of random mutations are harmful. The number of random mutations necessary to produce one lung cell that is better adapted to smoke inhalation is large enough that the entire remainder of the lung already has carcinogenic mutations. Sexual reproduction is a mechanism to eliminate harmful mutations without discarding the occasional beneficial mutation. It is not necessary for that purpose, but it is sufficient. Humans are now technically capable of identifying a potentially beneficial genetic mutation, and inserting it into an unrelated person's genome. It is, however, more likely that the protein result of the mutation will be used to research and develop a pharmaceutical drug or medical procedure that replicates the beneficial effects of the mutation. In short, the probability of you spontaneously developing an adaptive mutation in a non-germline cell is absolutely infinitesimal in comparison to the probability that someone in the last 10000 generations of your ancestors developed such a mutation when producing a sperm or egg cell and passed it along to you.
- logfromblammo 10y ago
  Evolution occurs via reproduction over the span of many generations. Individual adaptation on a single-lifespan scale occurs via epigenetic methylation tagging of the existing (evolved) genome. You cannot become better adapted to smoke unless your genome already contains a gene that mitigates the damage, or a gene that can regulate expression of a damage-mitigating gene based on that specific stimulus. So if you breathe smoke frequently over your lifespan, you may have a gene related to mucus in the lungs expressing its protein at maximum capacity 24-7, while someone who never breathes smoke has that gene "turned off" most of the time. Transfer of individual adaptations, usually in the form of antibodies that can teach immune cells to respond to a specific hazard, is very limited, and will only last as long as that specific threat is continuously endemic. We have mostly supplanted that natural capacity with artificial vaccinations. Random mutations are usually harmful. Sexual reproduction and selection is the mechanism to shuffle the most harmful mutations out of the genome while still retaining the rare beneficial mutation. If the mutation rate is too low, the species cannot evolve quickly enough in changing environments. If the mutation rate is too high, sexual reproduction cannot eliminate the bad mutations fast enough.
patrickg_zill 10y ago
I think you are saying that there is no teleology in the theory of evolution.
inimino 10y ago
> humans evolve to develop a particular trait > people who developed that trait got an evolutionary advantage and ended up spreading their DNA more than others on average. The first is shorthand for the second.
- VeejayRampay 10y ago
  Ah OK, my bad then.
- iand 10y ago
  It's sloppy shorthand though because it can be (deliberately) misconstrued to suggest agency and directional purpose.

posterboy 10y ago

> it reads like humans evolve to develop a particular trait, when we know that people who developed that trait got an people who developed that trait had to evolve to do so, no? Not as an entire population, but maybe over the live span of individuals. Maybe the smoke itself caused that, as exposure often does, "evolving" in some individuals who then pass immunity markers down over generations through blood in the womb rather than genetically. Or maybe the smoke is cancerous and caused beneficial mutations. I should read the paper (edit: it says genetic). All I'm trying to say is, either development is subsumed under evolution.

inimino 10y ago
> people who developed that trait had to evolve to do so, no? The word "evolve" in English means a gradual change, so no. Random genetic mutation isn't a response to the smoke, and there isn't anybody born unadapted who then adapts by exposure. The species evolves, individuals don't.
- nonbel 10y ago
  >"The species evolves, individuals don't." You are made of cells that are many generations separated from the fertilized egg. I don't see why you accept evolution at the species level but not cell level. This sounds like a kind of reverse creationism, where macro-evolution is ok but micro-evolution is not.
  - inimino 10y ago
    Um, honestly not sure what you're getting at there. The individual cells in your body are genetically the same as what you started with, with occasional random mutations. The body defends itself against those mutations and most will be eliminated. Some will become cancers. They don't affect the DNA you pass on to your offspring and so aren't a part of the evolution of your species. None of them are going to give you superpowers unless you happen to be living in a comic book.
    - nonbel 10y ago
      Say a person is exposed to smoke often since being a young child. At some point, a lung cell is dividing and randomly gains a mutation that increases expression of some smoke-protective protein. This lung cell is then more fit (to the smokey environment) than the surrounding lung cells. As a result, its daughter cells will divide more often than the others and populate the tissue. Are you denying this can happen? Or is it that you do not consider that process to be evolution?
      - alecmckinley 10y ago
        That absolutely can happen - but remember that the traits of the 'evolved' lung cell will not be passed to offspring, as the genetic makeup of gametes (sperm) is a random (50%) subset of the main genetic code.
        nonbel 10y ago
        Sure, but the population of cells we call an individual human being does "evolve" over the course of its life.
        logfromblammo 10y ago
        The vast majority of random mutations are harmful. The number of random mutations necessary to produce one lung cell that is better adapted to smoke inhalation is large enough that the entire remainder of the lung already has carcinogenic mutations. Sexual reproduction is a mechanism to eliminate harmful mutations without discarding the occasional beneficial mutation. It is not necessary for that purpose, but it is sufficient. Humans are now technically capable of identifying a potentially beneficial genetic mutation, and inserting it into an unrelated person's genome. It is, however, more likely that the protein result of the mutation will be used to research and develop a pharmaceutical drug or medical procedure that replicates the beneficial effects of the mutation. In short, the probability of you spontaneously developing an adaptive mutation in a non-germline cell is absolutely infinitesimal in comparison to the probability that someone in the last 10000 generations of your ancestors developed such a mutation when producing a sperm or egg cell and passed it along to you.
logfromblammo 10y ago
Evolution occurs via reproduction over the span of many generations. Individual adaptation on a single-lifespan scale occurs via epigenetic methylation tagging of the existing (evolved) genome. You cannot become better adapted to smoke unless your genome already contains a gene that mitigates the damage, or a gene that can regulate expression of a damage-mitigating gene based on that specific stimulus. So if you breathe smoke frequently over your lifespan, you may have a gene related to mucus in the lungs expressing its protein at maximum capacity 24-7, while someone who never breathes smoke has that gene "turned off" most of the time. Transfer of individual adaptations, usually in the form of antibodies that can teach immune cells to respond to a specific hazard, is very limited, and will only last as long as that specific threat is continuously endemic. We have mostly supplanted that natural capacity with artificial vaccinations. Random mutations are usually harmful. Sexual reproduction and selection is the mechanism to shuffle the most harmful mutations out of the genome while still retaining the rare beneficial mutation. If the mutation rate is too low, the species cannot evolve quickly enough in changing environments. If the mutation rate is too high, sexual reproduction cannot eliminate the bad mutations fast enough.

patrickg_zill 10y ago

I think you are saying that there is no teleology in the theory of evolution.

inimino 10y ago

> humans evolve to develop a particular trait > people who developed that trait got an evolutionary advantage and ended up spreading their DNA more than others on average. The first is shorthand for the second.

VeejayRampay 10y ago
Ah OK, my bad then.
iand 10y ago
It's sloppy shorthand though because it can be (deliberately) misconstrued to suggest agency and directional purpose.