3 ms·

> 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 resp

by 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.
        nonbel 10y ago
        Many interesting points here that I wish were backed up by refs. > "The vast majority of random mutations are harmful." - You sure they aren't "neutral"? > "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." - No, in principle it can be a single point mutation to a promoter that increases affinity for a transcription factor. > "Sexual reproduction is a mechanism to eliminate harmful mutations without discarding the occasional beneficial mutation." - So are apotosis and immune surveillance. > "Humans are now technically capable of identifying a potentially beneficial genetic mutation, and inserting it into an unrelated person's genome." - No, they aren't. They modify and select cells in a dish, not in a person. > "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." - Ok, I am just including this for completeness sake. > "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." - You are talking of 10^4 fertilized eggs vs 10^13 cells in my body[1]. I'm not sure how many divisions it is from egg to egg, but it has to be less than the 10^16 supposed to happen during the human life span[2]. Actually I am pretty sure I have read somewhere that the human body probably contains at least one cell that has a mutation at any given bp. I will see if there is time to find it later. [1] https://www.ncbi.nlm.nih.gov/pubmed/23829164 https://www.ncbi.nlm.nih.gov/pubmed/23829164 [2] http://bionumbers.hms.harvard.edu/bionumber.aspx?id=100379 http://bionumbers.hms.harvard.edu/bionumber.aspx?id=100379

by inimino 10y ago

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.
        nonbel 10y ago
        Many interesting points here that I wish were backed up by refs. > "The vast majority of random mutations are harmful." - You sure they aren't "neutral"? > "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." - No, in principle it can be a single point mutation to a promoter that increases affinity for a transcription factor. > "Sexual reproduction is a mechanism to eliminate harmful mutations without discarding the occasional beneficial mutation." - So are apotosis and immune surveillance. > "Humans are now technically capable of identifying a potentially beneficial genetic mutation, and inserting it into an unrelated person's genome." - No, they aren't. They modify and select cells in a dish, not in a person. > "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." - Ok, I am just including this for completeness sake. > "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." - You are talking of 10^4 fertilized eggs vs 10^13 cells in my body[1]. I'm not sure how many divisions it is from egg to egg, but it has to be less than the 10^16 supposed to happen during the human life span[2]. Actually I am pretty sure I have read somewhere that the human body probably contains at least one cell that has a mutation at any given bp. I will see if there is time to find it later. [1] https://www.ncbi.nlm.nih.gov/pubmed/23829164 https://www.ncbi.nlm.nih.gov/pubmed/23829164 [2] http://bionumbers.hms.harvard.edu/bionumber.aspx?id=100379 http://bionumbers.hms.harvard.edu/bionumber.aspx?id=100379