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When I read "humans didn't use", I understand that other animals with which we share close common ancestors still use it. Evolutionary pressure can make organs

When I read "humans didn't use", I understand that other animals with which we share close common ancestors still use it. Evolutionary pressure can make organs go into disuse so it makes sense that we end up with unused organs.

parineum 2y ago
Evolutionary pressure also would select for not wasting energy on a useless organ.
- _Algernon_ 2y ago
  The selective pressure of small unused organs may be very low and virtually disappear in the stochasticity of natural selection. It may take a long time for such elements to disappear completely
roenxi 2y ago
A 1% reduction in body mass is a huge advantage evolutionary, especially since rather than being cut completely that mass could be repurposed as more muscle for competing or more fat for lean times. For something in very recent evolutionary history (talking the last few thousand years), yeah sure the pressure might not have optimised a wasted organ out. But for any random organ? Nah, they probably have a purpose and we don't know what it is yet. Otherwise there is a big advantage to removing 'useless' bits. Evolutionary processes do however love little random tweaks and whatnot because they serve a useful purpose in weird edge cases and it is much more likely we're looking at one of them in any particular case.
- jjk166 2y ago
  And the ability to breath fire would also be a huge advantage, but evolution does not seek advantages, it merely keeps mutations that happen to be beneficial. No one has been born with a mutation that has allowed them to breath fire (or if they were they obviously didn't have much reproductive success) and thus we are still unable to breath fire. No one who has been born with a mutation that prevents the development of ear muscles has had especially great reproductive success either.
  - roenxi 2y ago
    Well no, being able to breath fire is probably evolutionarily stupid. There is no reason to think it would be helpful, it'd presumably involve animals building up a highly flammable concoction inside their bodies and occasionally exploding. For no gain, since they could do what everyone else does and gather combustible material and set it alight. And flamethrowers just aren't very effective weapons on average since they'd tend to burn an animal's home down or be very energetically demanding for no upside vs something like a good pair of jaws or claws. If evolution can figure out photosynthesis it can figure out flammability. Flammability is actually pretty easy. Even monkeys can manage it. There probably have been animals that breath fire and it just didn't catch on because it is wholly impractical.
    - jjk166 2y ago
      Substitute any other adaptation that provides benefit but for which the necessary combination of mutations is unlikely to occur.
- dahart 2y ago
  > A 1% reduction in body mass is a huge advantage evolutionary That thought fails to explain the wide natural variation in body mass of humans, and within each species on this planet. Edit: for most species being smaller is a disadvantage. Mates statistically select for larger stronger individuals, and larger stronger individuals are statistically better at killing and defending.
  - JoeAltmaier 2y ago
    A little study of biology will clear that up. Species inhabit different niches. They have different survival strategies. Each case requires a different optimal point.
    - dahart 2y ago
      Please elaborate, I think you misunderstood me. Are you defending the claim that 1% human body mass reduction is an evolutionary advantage? Your quip about biology should maybe be directed at @roenxi? I was talking about variation within each species, not across different species. (Edited to clarify) I was talking, in context as a reply to the claim that losing a given vestigial organ would improve (lessen) mortality. Humans, for example, have wide natural variation in body mass, therefore the evidence contradicts the claim that “1% reduction in body mass is a huge advantage evolutionary”. If a reduction in body mass was an evolutionary advantage, we’d be evolving to be smaller over time. That’s not happening. Why? In fact, there is an evolutionary advantage in humans to being taller and having more muscle, since these traits are selected for by mates, and are beneficial for hunting.
      - JoeAltmaier 2y ago
        That is the naïve one-variable approach which breaks down immediately. Features all evolve together, the individual thrives or dies as one organism. Any change in one variable affects all the others, e.g. drop body mass releases calories for other survival purposes. Any increase over the critical need consumes resources better used for other things.

parineum 2y ago

Evolutionary pressure also would select for not wasting energy on a useless organ.

_Algernon_ 2y ago
The selective pressure of small unused organs may be very low and virtually disappear in the stochasticity of natural selection. It may take a long time for such elements to disappear completely

roenxi 2y ago

A 1% reduction in body mass is a huge advantage evolutionary, especially since rather than being cut completely that mass could be repurposed as more muscle for competing or more fat for lean times. For something in very recent evolutionary history (talking the last few thousand years), yeah sure the pressure might not have optimised a wasted organ out. But for any random organ? Nah, they probably have a purpose and we don't know what it is yet. Otherwise there is a big advantage to removing 'useless' bits. Evolutionary processes do however love little random tweaks and whatnot because they serve a useful purpose in weird edge cases and it is much more likely we're looking at one of them in any particular case.

jjk166 2y ago
And the ability to breath fire would also be a huge advantage, but evolution does not seek advantages, it merely keeps mutations that happen to be beneficial. No one has been born with a mutation that has allowed them to breath fire (or if they were they obviously didn't have much reproductive success) and thus we are still unable to breath fire. No one who has been born with a mutation that prevents the development of ear muscles has had especially great reproductive success either.
- roenxi 2y ago
  Well no, being able to breath fire is probably evolutionarily stupid. There is no reason to think it would be helpful, it'd presumably involve animals building up a highly flammable concoction inside their bodies and occasionally exploding. For no gain, since they could do what everyone else does and gather combustible material and set it alight. And flamethrowers just aren't very effective weapons on average since they'd tend to burn an animal's home down or be very energetically demanding for no upside vs something like a good pair of jaws or claws. If evolution can figure out photosynthesis it can figure out flammability. Flammability is actually pretty easy. Even monkeys can manage it. There probably have been animals that breath fire and it just didn't catch on because it is wholly impractical.
  - jjk166 2y ago
    Substitute any other adaptation that provides benefit but for which the necessary combination of mutations is unlikely to occur.
dahart 2y ago
> A 1% reduction in body mass is a huge advantage evolutionary That thought fails to explain the wide natural variation in body mass of humans, and within each species on this planet. Edit: for most species being smaller is a disadvantage. Mates statistically select for larger stronger individuals, and larger stronger individuals are statistically better at killing and defending.
- JoeAltmaier 2y ago
  A little study of biology will clear that up. Species inhabit different niches. They have different survival strategies. Each case requires a different optimal point.
  - dahart 2y ago
    Please elaborate, I think you misunderstood me. Are you defending the claim that 1% human body mass reduction is an evolutionary advantage? Your quip about biology should maybe be directed at @roenxi? I was talking about variation within each species, not across different species. (Edited to clarify) I was talking, in context as a reply to the claim that losing a given vestigial organ would improve (lessen) mortality. Humans, for example, have wide natural variation in body mass, therefore the evidence contradicts the claim that “1% reduction in body mass is a huge advantage evolutionary”. If a reduction in body mass was an evolutionary advantage, we’d be evolving to be smaller over time. That’s not happening. Why? In fact, there is an evolutionary advantage in humans to being taller and having more muscle, since these traits are selected for by mates, and are beneficial for hunting.
    - JoeAltmaier 2y ago
      That is the naïve one-variable approach which breaks down immediately. Features all evolve together, the individual thrives or dies as one organism. Any change in one variable affects all the others, e.g. drop body mass releases calories for other survival purposes. Any increase over the critical need consumes resources better used for other things.