41–50 of 54 posts
I don't where I heard this, or if it is true, but it has been my favorite (maybe fake) animal fact: There is a reason the stripes are BLACK and WHITE. One absorbs the light and the other reflects, which in turn makes a slight difference of air temperature right above the skin surface. The difference of temperatures in certain areas cause (slight) differences in air pressure. This can cause a shallow "wind coat" aroun…
Evolution doesn’t answer to a single why question. Maybe the stripes have been useful to the zebra population’s survival, maybe not – but it is quite clear.that there is no singular reason but a bundle of things. E.g. the stripes make zebras harder to distinguish in a herd, which certainly lead to some percentage of survival. Flies too? Cool! But answering it as if there was some intention behind it? That is not how…
> the stripes make zebras harder to distinguish in a herd, which certainly lead to some percentage of survival From the article: > Amanda Melin of the University of Calgary recently showed that lions and hyenas can’t even make out the stripes unless they get very close.
Sounds like it could still influence hunting as the predators have to get very close to make a kill
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.
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 dom…
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.
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.
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 trai…
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.
I wonder if CV systems will be similarly catastrophically perplexed? Imagine laying out the zebra rug for an Amazon drone delivery
No, its pretty obvious to recognize a zebra using a neural net (e.g. resnet)
Evolution doesn’t answer to a single why question. Maybe the stripes have been useful to the zebra population’s survival, maybe not – but it is quite clear.that there is no singular reason but a bundle of things. E.g. the stripes make zebras harder to distinguish in a herd, which certainly lead to some percentage of survival. Flies too? Cool! But answering it as if there was some intention behind it? That is not how…
Evolution selects for traits correlated with successful reproduction. Correlation doesn't imply causation. All evolution can do is say "hey, things with this trait worked better, let's build more of these."
Earlier quoted context omitted.
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 dom…
> 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…
Doesn't it sound like such diseases are likely to alter a zebra's fecundity?
Evolution doesn’t answer to a single why question. Maybe the stripes have been useful to the zebra population’s survival, maybe not – but it is quite clear.that there is no singular reason but a bundle of things. E.g. the stripes make zebras harder to distinguish in a herd, which certainly lead to some percentage of survival. Flies too? Cool! But answering it as if there was some intention behind it? That is not how…
While you raise a good point about evolution being inscrutable - the stripes do effect files... " By watching and filming the stable’s horses and zebras, the team confirmed that horseflies were much worse at alighting on the latter. The flies had no problem finding the zebras or approaching them, but couldn’t stick the landing. “You get a quarter as many landings,” Caro said. “The flies just can’t probe for a blood m…
My critique was pointed at the wording. IMO it is not about why a trait evolved – there are many useless traits that envolved somewhere during special conditions and after these conditions change remain for a eternity or suddenly find a new usefulness in changed circumstances. This means pinpointing such a trait down to a single why is not a good representation of reality.
Are such observations valuable? For sure! Nature developed amazing strategies for all kind of things and not looking at these would be a waste.
I’d just be a bit more cautios with quick conclusions that involve meaning and answering why-questions, that’s all
Evolution doesn’t answer to a single why question. Maybe the stripes have been useful to the zebra population’s survival, maybe not – but it is quite clear.that there is no singular reason but a bundle of things. E.g. the stripes make zebras harder to distinguish in a herd, which certainly lead to some percentage of survival. Flies too? Cool! But answering it as if there was some intention behind it? That is not how…
This nitpick is brought up each time someone makes an interesting observation. I can only image it is because people are trying to preempt intelligent design nonsense.
You are ofc right, it had no purpose when you talk generation to generation, the gradual tiny mutation each time did indeed serve no purpose.
But when you talk about the end product, the striped zebra, it is ok to say zebras (as the product of those millions of tiny iterations) might have evolved to discourage biting flies. Of course it could have been some other reason altogether, or a mixture of reasons but there is nothing wrong with the vocabulary, imo.