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It's sometimes underestimated at what level of detail evolution operates. Consider this: there must have been quite a lot of prehistoric humans who died, or ot

It's sometimes underestimated at what level of detail evolution operates. Consider this: there must have been quite a lot of prehistoric humans who died, or otherwise suffered reproductive failure, because they lacked eyebrows. Breaking major bones, especially in times before modern medicine, was without a doubt a life-threatening event. And considering the prevalence of fractures today, with our largely sedentary lives, it must have happened fairly often

masklinn 9y ago
> Breaking major bones, especially in times before modern medicine, was without a doubt a life-threatening event. And considering the prevalence of fractures today, with our largely sedentary lives, it must have happened fairly often They're not that prevalent, and they may not have been more prevalent in the past, sedentary life likely contributes to some form of osteoporosis by providing less continuous stress and it adds "extreme" sports as discrete high-risk events. And of course just because it's life threatening does not mean it's going to be weeded out, selection is an important part of evolution.
- toasterlovin 9y ago
  I think many people greatly underestimate the degree to which the body is an adaptive system and, specifically, the degree to which a sedentary lifestyle interacts poorly with this aspect of our bodies. The thing that brought this into full relief for me was the story of Brian Jones, a member of the Starting Strength community. He fell off of a roof and shattered both legs. Doctor told him he would never walk again, etc., etc. But he did. And then he start lifting weights. Of course, his body adapted to the increasing load he was placing on it. Specifically, his body responded by growing muscle and making his bones more dense. His bones got so dense that the metal pins which were inserted into his leg bones after his accident started getting pushed out into the surrounding flesh and he had to have surgery to remove them (links to his story below). I would bet good money that the majority of bone breaks (excluding things like car crashes and obvious stupidity), even in children, are a result of our largely sedentary lifestyles interacting with our body's evolved tendency to not engage in metabolically expensive activity like growing muscle and denser bone unless it receives signals indicating that they are actually demanded by our environment. Brian Jones' story: Video form: https://startingstrength.com/resources/forum/articles-and-platform-videos/40189-barbell-training-rehab-brian-jones-story.html https://startingstrength.com/resources/forum/articles-and-pl... Written form: https://startingstrength.com/article/barbell_training_as_rehab https://startingstrength.com/article/barbell_training_as_reh...
  - fjsolwmv 9y ago
    Brian Jones is an extreme person. Prehistoric man couldn't replicate his level of executive
    - toasterlovin 9y ago
      On the contrary: that Brian Jones (along with many other men) possesses a body which is capable of getting strong enough to lift 600+ lbs off the floor is pretty strong evidence that our evolutionary past often required humans to get pretty damned strong.
      - njarboe 9y ago
        I imagine that hunters that could carry large heavy loads of meat that they killed back to the cave/tribe would have been positively selected for since a least the invention of the spear. Spears are older than the human species at around a million years ago. Plenty of time to evolve very strong hominids.
- fjsolwmv 9y ago
  Even active children frequently break bones. But of course dead children are relatively cheap for how many you actually need to survive, it's easy to make extra and lose a few,
  - masklinn 9y ago
    And children used to die all the time for all sorts of reasons, even just a pair of generations back, in total my grandparents (father's side) had 16 children (live births, I don't even know if there were still birth), but only 12 made it out of childhood. Broken bones were not an issue, but farm machinery & various diseases were.
toasterlovin 9y ago
> There must have been quite a lot of prehistoric humans who died, or otherwise suffered reproductive failure, because they lacked eyebrows A bit pedantic, but: there doesn't need to be a direct line between a morphological feature, like eyebrows, and death and/or inability to reproduce. Evolution is a statistical process that operates over an entire population of organisms. So, a feature like eyebrows can evolve even if they have a relatively minor impact on organisms with eyebrows, like, say, by making them 3% better at hunting or whatever. Because if you have a population of thousands or millions of organisms, that 3% hunting advantage will make a difference.
- falcor84 9y ago
  I'd argue that being 3% worse at hunting than one's competitors can definitely become a reproductive failure.
  - toasterlovin 9y ago
    Agree, but only at the margins. That one thing, in and of itself isn't a reproductive failure. But over a population with varying levels of, say, hunting proficiency, there will be enough people who are already not very good at hunting and a gene that makes you 3% worse will result in them having less or no children.
    - lurquer 9y ago
      Is there a correlation between reproduction and eyebrows? Seems like a simple thing to study. I doubt anyone has. (And, I doubt anyone will.) It's easier to simply conjure up stories about how eyebrows must have had some beneficial effect and then hand-wave while muttering 'millions and millions.' Given the assumed population levels, the timescales involved, and the minuscule statistical effect of something like eyebrow-ness on survival, I expect 'survival of the fittest' had nothing to do with eyebrows. Rather, it's just a random bit of 'noise' in our DNA.
      - toasterlovin 9y ago
agumonkey 9y ago
Oh it surely was a life threatening event, but it was solved long before humans were upright. After that it was mostly tweaking. About sedentary lives, I'm fairly convinced that nomadism made for stronger everything, bones, tendons, muscles (coordination too) so their lifestyle (granted you're not living near cliffs and have enough food) didn't increase the % of fracture.
stcredzero 9y ago
It's sometimes underestimated at what level of detail evolution operates. Of course human minds would tend to underestimate this. Evolution harnesses the parallelism inherent in reality and atoms. Natural selection operates at all levels of detail at once.

masklinn 9y ago

> Breaking major bones, especially in times before modern medicine, was without a doubt a life-threatening event. And considering the prevalence of fractures today, with our largely sedentary lives, it must have happened fairly often They're not that prevalent, and they may not have been more prevalent in the past, sedentary life likely contributes to some form of osteoporosis by providing less continuous stress and it adds "extreme" sports as discrete high-risk events. And of course just because it's life threatening does not mean it's going to be weeded out, selection is an important part of evolution.

toasterlovin 9y ago
I think many people greatly underestimate the degree to which the body is an adaptive system and, specifically, the degree to which a sedentary lifestyle interacts poorly with this aspect of our bodies. The thing that brought this into full relief for me was the story of Brian Jones, a member of the Starting Strength community. He fell off of a roof and shattered both legs. Doctor told him he would never walk again, etc., etc. But he did. And then he start lifting weights. Of course, his body adapted to the increasing load he was placing on it. Specifically, his body responded by growing muscle and making his bones more dense. His bones got so dense that the metal pins which were inserted into his leg bones after his accident started getting pushed out into the surrounding flesh and he had to have surgery to remove them (links to his story below). I would bet good money that the majority of bone breaks (excluding things like car crashes and obvious stupidity), even in children, are a result of our largely sedentary lifestyles interacting with our body's evolved tendency to not engage in metabolically expensive activity like growing muscle and denser bone unless it receives signals indicating that they are actually demanded by our environment. Brian Jones' story: Video form: https://startingstrength.com/resources/forum/articles-and-platform-videos/40189-barbell-training-rehab-brian-jones-story.html https://startingstrength.com/resources/forum/articles-and-pl... Written form: https://startingstrength.com/article/barbell_training_as_rehab https://startingstrength.com/article/barbell_training_as_reh...
- fjsolwmv 9y ago
  Brian Jones is an extreme person. Prehistoric man couldn't replicate his level of executive
  - toasterlovin 9y ago
    On the contrary: that Brian Jones (along with many other men) possesses a body which is capable of getting strong enough to lift 600+ lbs off the floor is pretty strong evidence that our evolutionary past often required humans to get pretty damned strong.
    - njarboe 9y ago
      I imagine that hunters that could carry large heavy loads of meat that they killed back to the cave/tribe would have been positively selected for since a least the invention of the spear. Spears are older than the human species at around a million years ago. Plenty of time to evolve very strong hominids.
fjsolwmv 9y ago
Even active children frequently break bones. But of course dead children are relatively cheap for how many you actually need to survive, it's easy to make extra and lose a few,
- masklinn 9y ago
  And children used to die all the time for all sorts of reasons, even just a pair of generations back, in total my grandparents (father's side) had 16 children (live births, I don't even know if there were still birth), but only 12 made it out of childhood. Broken bones were not an issue, but farm machinery & various diseases were.

toasterlovin 9y ago

> There must have been quite a lot of prehistoric humans who died, or otherwise suffered reproductive failure, because they lacked eyebrows A bit pedantic, but: there doesn't need to be a direct line between a morphological feature, like eyebrows, and death and/or inability to reproduce. Evolution is a statistical process that operates over an entire population of organisms. So, a feature like eyebrows can evolve even if they have a relatively minor impact on organisms with eyebrows, like, say, by making them 3% better at hunting or whatever. Because if you have a population of thousands or millions of organisms, that 3% hunting advantage will make a difference.

falcor84 9y ago
I'd argue that being 3% worse at hunting than one's competitors can definitely become a reproductive failure.
- toasterlovin 9y ago
  Agree, but only at the margins. That one thing, in and of itself isn't a reproductive failure. But over a population with varying levels of, say, hunting proficiency, there will be enough people who are already not very good at hunting and a gene that makes you 3% worse will result in them having less or no children.
  - lurquer 9y ago
    Is there a correlation between reproduction and eyebrows? Seems like a simple thing to study. I doubt anyone has. (And, I doubt anyone will.) It's easier to simply conjure up stories about how eyebrows must have had some beneficial effect and then hand-wave while muttering 'millions and millions.' Given the assumed population levels, the timescales involved, and the minuscule statistical effect of something like eyebrow-ness on survival, I expect 'survival of the fittest' had nothing to do with eyebrows. Rather, it's just a random bit of 'noise' in our DNA.
    - toasterlovin 9y ago

agumonkey 9y ago

Oh it surely was a life threatening event, but it was solved long before humans were upright. After that it was mostly tweaking. About sedentary lives, I'm fairly convinced that nomadism made for stronger everything, bones, tendons, muscles (coordination too) so their lifestyle (granted you're not living near cliffs and have enough food) didn't increase the % of fracture.

stcredzero 9y ago

It's sometimes underestimated at what level of detail evolution operates. Of course human minds would tend to underestimate this. Evolution harnesses the parallelism inherent in reality and atoms. Natural selection operates at all levels of detail at once.