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If the theory of evolution is correct, then there is no why to any animal trait. There's no "reason" for the traits, it only happens that maybe some traits allo

If the theory of evolution is correct, then there is no why to any animal trait. There's no "reason" for the traits, it only happens that maybe some traits allowed the species to survive longer and so they are still around today, but that doesn't mean "someone" enforced a certain trait with a certain purpose. So, a more scientifically oriented title should be: What do Stripes do for Zebras? Shoo away flies.

vntok 8y ago
No, that's a common mistake. In fact, there can be causation without a sentient causal entity. Zebras have stripes because their stripes shoo away flies, which helped previous generations of zebras who had stripes thrive and pass their genes forward. Why do zebras have stripes? Because they shoo flies away and evolution ensured that that helpful trait kept passing through descendants until every zebra had it as a dominant, visible trait. No one ever said there had to be "someone" somewhere to paint zebras black and white, that's just you using anthropomorphized evolution as a straw man/entity.
- laszlokorte 8y ago
  It's still a philosophical debate if such an phenomenon can be seen as cause and effect. It's a similar problem as with teleological views in eg biology and medicine: "what's the task/purpose of the lungs?" - there is no predefined task.
- the_af 8y ago
  > Zebras have stripes because their stripes shoo away flies, which helped previous generations of zebras who had stripes thrive and pass their genes forward. Not necessarily. A trait may also be there simply because it's not actively harmful, or maybe because it's a useless side-effect of another trait that is beneficial. It may be that zebras have stripes because they are not harmful enough to prevent them from passing their genes forward. (of course, in this particular case the flies hypothesis seems more likely).
- lurquer 8y ago
  > which helped previous generations of zebras who had stripes thrive and pass their genes forward. You don't know that. The article doesn't even bother to test it. They've observed that stripes lead to fewer horsefly landings. Interesting. I guess. But, talking about evolution is a non sequitor. Show me the data where a zebra's fecundity is related to the number of horsefly bites it receives. There isn't any. One can speculate about such things. But, if one wishes to be scientific, test to see if there is a measurable effect. For all we know, zebras with MORE horsefly bites are MORE likely to reproduce. There simply is no data in the article one way or the other. So bringing up evolution is just mindless unscientific just-so-storytelling.
  - vntok 8y ago
    Animal trypanosomiasis, transmitted by tsetse flies, causes "fever, weakness, and lethargy, which lead to weight loss and anemia; in some animals the disease is fatal unless treated". Doesn't it sound like such diseases are likely to alter a zebra's fecundity?
    - lurquer 8y ago
      The study involved horseflies in England... not tse-tse flies in Africa. As far as the effect of 'such diseases' on a zebra's fecundity, I have no idea. For all we know, a feverish lethargic zebra is EASIER for a stallion to mount than a healthy zebra. Nobody knows. The study, incidentally, did not deal with the types of flies accustomed to biting zebras. I have every reason to think a typical African biting fly would have no problem alighting on a zebra... it's what they do for a living.
PeterisP 8y ago
While it only happens that some traits allowed the species to survive longer (or multiply more), there's still the "reason why" - there's generally a specific mechanism (or multiple mechanisms) how exactly that trait allows the species to survive longer or multiply more. As that particular mechanism is the reason for that trait being useful, it's also the reason (cause) for that trait to having outcompeted other traits. So, there's nothing wrong with the title of "Why do Zebras have stripes [other than the obvious default non-answer 'because stripes are somehow good for them']? To Shoo Away Flies." I.e. "why do they have Y" is "why" in the sense "what's the reason/cause of Y's continued existence".
- ta1234567890 8y ago
  Well, you are choosing a reason. That doesn't make it the reason. Sure you can say Zebras have black and white stripes because their genes makes them express them in a certain way. However I could say they have stripes because it helps them shoo away flies. Someone else could say they have stripes because it makes them look pretty. Another person yet could say they only seem to have stripes because we can see those colors, but some other animals can't see them, so to us they have stripes. And then anyone could keep coming up with alternative answers. Even worse, you could ask why the mechanism that makes the Zebras have stripes works that way? And then why is that so. And then there's technically no end to it (just talk to any little kid). We just accept the first seemingly reasonable answer to a why question, and we've been trained it's rude or annoying to keep asking. But there's really no definitive answer, except whichever one you choose to accept.
  - PeterisP 8y ago
    The choice of reason isn't arbitrary. You could say that they have stripes because it helps them shoo away flies and someone else could say they have stripes because it makes them look pretty - but one (or both) of these answers would be wrong. The hypothesis can be falsified. We could test whether zebras do find stripes pretty in other zebras - perhaps it's not the best way to spend your time and resources, but it can be done. We can measure whether stripes discourage flies from landing, and we can measure what impact (if any) less flies has on health of zebras and their likelihood to survive until breeding. It's tricky, but it's generally possible. There's some mechanism that makes stripes beneficial. Or perhaps there are multiple valid mechanisms - but in that case, one contributes (for example) 70% and the other 30%, and that can (with enough effort) be evaluated, and those mechanisms separated from the other alternative answers that are just guesses. There are definitive answers. Perhaps they're hard to find out, perhaps they're hard to verify, perhaps for some aspects we'll not find out these definitive answers, but they certainly are there. You may reasonably choose that a particular answer isn't important enough to justify the resources needed to obtain that answer (and zebra stripes may well be a decent example for that), but giving in to the concept "there's really no definitive answer, except whichever one you choose to accept" is just shameful wilful ignorance. Reality is what exists no matter if you choose to accept it or not.
joaomacp 8y ago
"Why do humans have teeth? To chew food" Doesn't look bad to me, and it's the same exact point.

vntok 8y ago

No, that's a common mistake. In fact, there can be causation without a sentient causal entity. Zebras have stripes because their stripes shoo away flies, which helped previous generations of zebras who had stripes thrive and pass their genes forward. Why do zebras have stripes? Because they shoo flies away and evolution ensured that that helpful trait kept passing through descendants until every zebra had it as a dominant, visible trait. No one ever said there had to be "someone" somewhere to paint zebras black and white, that's just you using anthropomorphized evolution as a straw man/entity.

laszlokorte 8y ago
It's still a philosophical debate if such an phenomenon can be seen as cause and effect. It's a similar problem as with teleological views in eg biology and medicine: "what's the task/purpose of the lungs?" - there is no predefined task.
the_af 8y ago
> Zebras have stripes because their stripes shoo away flies, which helped previous generations of zebras who had stripes thrive and pass their genes forward. Not necessarily. A trait may also be there simply because it's not actively harmful, or maybe because it's a useless side-effect of another trait that is beneficial. It may be that zebras have stripes because they are not harmful enough to prevent them from passing their genes forward. (of course, in this particular case the flies hypothesis seems more likely).
lurquer 8y ago
> which helped previous generations of zebras who had stripes thrive and pass their genes forward. You don't know that. The article doesn't even bother to test it. They've observed that stripes lead to fewer horsefly landings. Interesting. I guess. But, talking about evolution is a non sequitor. Show me the data where a zebra's fecundity is related to the number of horsefly bites it receives. There isn't any. One can speculate about such things. But, if one wishes to be scientific, test to see if there is a measurable effect. For all we know, zebras with MORE horsefly bites are MORE likely to reproduce. There simply is no data in the article one way or the other. So bringing up evolution is just mindless unscientific just-so-storytelling.
- vntok 8y ago
  Animal trypanosomiasis, transmitted by tsetse flies, causes "fever, weakness, and lethargy, which lead to weight loss and anemia; in some animals the disease is fatal unless treated". Doesn't it sound like such diseases are likely to alter a zebra's fecundity?
  - lurquer 8y ago
    The study involved horseflies in England... not tse-tse flies in Africa. As far as the effect of 'such diseases' on a zebra's fecundity, I have no idea. For all we know, a feverish lethargic zebra is EASIER for a stallion to mount than a healthy zebra. Nobody knows. The study, incidentally, did not deal with the types of flies accustomed to biting zebras. I have every reason to think a typical African biting fly would have no problem alighting on a zebra... it's what they do for a living.

PeterisP 8y ago

While it only happens that some traits allowed the species to survive longer (or multiply more), there's still the "reason why" - there's generally a specific mechanism (or multiple mechanisms) how exactly that trait allows the species to survive longer or multiply more. As that particular mechanism is the reason for that trait being useful, it's also the reason (cause) for that trait to having outcompeted other traits. So, there's nothing wrong with the title of "Why do Zebras have stripes [other than the obvious default non-answer 'because stripes are somehow good for them']? To Shoo Away Flies." I.e. "why do they have Y" is "why" in the sense "what's the reason/cause of Y's continued existence".

ta1234567890 8y ago
Well, you are choosing a reason. That doesn't make it the reason. Sure you can say Zebras have black and white stripes because their genes makes them express them in a certain way. However I could say they have stripes because it helps them shoo away flies. Someone else could say they have stripes because it makes them look pretty. Another person yet could say they only seem to have stripes because we can see those colors, but some other animals can't see them, so to us they have stripes. And then anyone could keep coming up with alternative answers. Even worse, you could ask why the mechanism that makes the Zebras have stripes works that way? And then why is that so. And then there's technically no end to it (just talk to any little kid). We just accept the first seemingly reasonable answer to a why question, and we've been trained it's rude or annoying to keep asking. But there's really no definitive answer, except whichever one you choose to accept.
- PeterisP 8y ago
  The choice of reason isn't arbitrary. You could say that they have stripes because it helps them shoo away flies and someone else could say they have stripes because it makes them look pretty - but one (or both) of these answers would be wrong. The hypothesis can be falsified. We could test whether zebras do find stripes pretty in other zebras - perhaps it's not the best way to spend your time and resources, but it can be done. We can measure whether stripes discourage flies from landing, and we can measure what impact (if any) less flies has on health of zebras and their likelihood to survive until breeding. It's tricky, but it's generally possible. There's some mechanism that makes stripes beneficial. Or perhaps there are multiple valid mechanisms - but in that case, one contributes (for example) 70% and the other 30%, and that can (with enough effort) be evaluated, and those mechanisms separated from the other alternative answers that are just guesses. There are definitive answers. Perhaps they're hard to find out, perhaps they're hard to verify, perhaps for some aspects we'll not find out these definitive answers, but they certainly are there. You may reasonably choose that a particular answer isn't important enough to justify the resources needed to obtain that answer (and zebra stripes may well be a decent example for that), but giving in to the concept "there's really no definitive answer, except whichever one you choose to accept" is just shameful wilful ignorance. Reality is what exists no matter if you choose to accept it or not.

joaomacp 8y ago

"Why do humans have teeth? To chew food" Doesn't look bad to me, and it's the same exact point.