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Why didn't they evolve?

by muninn_ 10y ago

farnsworth 10y ago
People tend to think that constant evolution is the natural state of the world becoming "more advanced". But really, evolution will only happen when there's a reason. This species is related to a bunch of other species that did evolve, but apparently it represents a group that managed to stay in conditions that it was already adequately adapted for. Or there was no beneficial direction available in which it could evolve.
- thaumasiotes 10y ago
  > People tend to think that constant evolution is the natural state of the world becoming "more advanced". But really, evolution will only happen when there's a reason. This is fallacious. It's so wrong that it overlooks the term ("genetic drift") that specifically describes evolution that happens "for no reason". All species constantly evolve, as noted in nn3's sibling comment to yours. This one has preserved its skeletal structure, which is an infinitesimal part of it. From the heading of https://en.wikipedia.org/wiki/Living_fossil https://en.wikipedia.org/wiki/Living_fossil: > The term living fossil is sometimes used in the popular literature, as if to imply a lack of evolution, and has occasionally also been taken to imply very low rates of molecular evolution, but scientific investigations have repeatedly discredited claims that these species do not change at all, as well as other misconceptions about living fossils. > Living fossils are not expected to exhibit exceptionally low rates of molecular evolution, and some studies have shown that they do not. For example, on tadpole shrimp (Triops), one article notes, "Our work shows that organisms with conservative body plans are constantly radiating, and presumably, adapting to novel conditions.... I would favor retiring the term ‘living fossil’ altogether, as it is generally misleading."
gus_massa 10y ago
One of the common error about evolution is that some people expect that any creature will evolve after certain time. I call it half joking the Pokemon model, were the specie accumulate experience points and then it magically evolve. These animals are somewhat similar to "rat from trees" or "squirrels" or your preferred small mammal that lives in trees and eats fruit and whatever it can found. I'm guessing a little because I'm not a biologist ... They probably lived all these years in a similar environment, i.e. trees in a tropical climate with lot of fruits and similar depredators. They live in an island, so they probably get few new fancy predator. They were well adapted for this environment 50mmy ago, they are well adapted now, and they were well adapted all the way down. So they had no good reason to evolve. The question is why all the other evolved? (more guessing here). Perhaps some of them lived in a place that get some new predators, and the trees were no longer safe, and they had to hide underground, so they evolved to loose the tail and change the hairs. (Actually, this means that the population had a few variants, and the variants with longer tail get cached more frequently by the predators, so the ones with shorter tail had more children, so the average tail is shorter. But now the variants with longer tail get cached more frequently by the predators, so the ones with shorter tail had more children, so the average tail is shorter. After a few repetitions, the original variant is extinct an you get a new specie.) Another possibility is that a part of the population get trapped in a zone with less trees with fruits and more grass wit seed, so they have to get used to walk in the floor instead of the trees, so they evolved a different kind of foots without. Another part of the population live near a river with a lot of dead fishes, and they become better eating them. The climate change, and the tree disappeared, but they like eating fish and they evolve a different mouth and teeth, and some of them realize that they can catch the fishes before they were already dead, ... After many of these changes and evolutions, you get giraffes, whales and humans ...
- thaumasiotes 10y ago
  > One of the common error about evolution is that some people expect that any creature will evolve after certain time. As I point out more thoroughly in response to farnsworth, that is not an error, it is correct. To prevent a species from evolving over time, it is necessary (though obviously not sufficient) that the breeding population be infinitely large.
nn3 10y ago
Likely they did, just not in a way visible in their skeleton. Bones and teeth are the only things paleontologists can study, but the real animal has many more parts invisible to them. For example they likely continuously evolved resistance against new diseases.

Why didn't they evolve?

by muninn_ 10y ago

Why didn't they evolve?

People tend to think that constant evolution is the natural state of the world becoming "more advanced". But really, evolution will only happen when there's a reason. This species is related to a bunch of other species that did evolve, but apparently it represents a group that managed to stay in conditions that it was already adequately adapted for. Or there was no beneficial direction available in which it could evolve.

thaumasiotes 10y ago
> People tend to think that constant evolution is the natural state of the world becoming "more advanced". But really, evolution will only happen when there's a reason. This is fallacious. It's so wrong that it overlooks the term ("genetic drift") that specifically describes evolution that happens "for no reason". All species constantly evolve, as noted in nn3's sibling comment to yours. This one has preserved its skeletal structure, which is an infinitesimal part of it. From the heading of https://en.wikipedia.org/wiki/Living_fossil https://en.wikipedia.org/wiki/Living_fossil: > The term living fossil is sometimes used in the popular literature, as if to imply a lack of evolution, and has occasionally also been taken to imply very low rates of molecular evolution, but scientific investigations have repeatedly discredited claims that these species do not change at all, as well as other misconceptions about living fossils. > Living fossils are not expected to exhibit exceptionally low rates of molecular evolution, and some studies have shown that they do not. For example, on tadpole shrimp (Triops), one article notes, "Our work shows that organisms with conservative body plans are constantly radiating, and presumably, adapting to novel conditions.... I would favor retiring the term ‘living fossil’ altogether, as it is generally misleading."

gus_massa 10y ago

One of the common error about evolution is that some people expect that any creature will evolve after certain time. I call it half joking the Pokemon model, were the specie accumulate experience points and then it magically evolve. These animals are somewhat similar to "rat from trees" or "squirrels" or your preferred small mammal that lives in trees and eats fruit and whatever it can found. I'm guessing a little because I'm not a biologist ... They probably lived all these years in a similar environment, i.e. trees in a tropical climate with lot of fruits and similar depredators. They live in an island, so they probably get few new fancy predator. They were well adapted for this environment 50mmy ago, they are well adapted now, and they were well adapted all the way down. So they had no good reason to evolve. The question is why all the other evolved? (more guessing here). Perhaps some of them lived in a place that get some new predators, and the trees were no longer safe, and they had to hide underground, so they evolved to loose the tail and change the hairs. (Actually, this means that the population had a few variants, and the variants with longer tail get cached more frequently by the predators, so the ones with shorter tail had more children, so the average tail is shorter. But now the variants with longer tail get cached more frequently by the predators, so the ones with shorter tail had more children, so the average tail is shorter. After a few repetitions, the original variant is extinct an you get a new specie.) Another possibility is that a part of the population get trapped in a zone with less trees with fruits and more grass wit seed, so they have to get used to walk in the floor instead of the trees, so they evolved a different kind of foots without. Another part of the population live near a river with a lot of dead fishes, and they become better eating them. The climate change, and the tree disappeared, but they like eating fish and they evolve a different mouth and teeth, and some of them realize that they can catch the fishes before they were already dead, ... After many of these changes and evolutions, you get giraffes, whales and humans ...

thaumasiotes 10y ago
> One of the common error about evolution is that some people expect that any creature will evolve after certain time. As I point out more thoroughly in response to farnsworth, that is not an error, it is correct. To prevent a species from evolving over time, it is necessary (though obviously not sufficient) that the breeding population be infinitely large.

nn3 10y ago

Likely they did, just not in a way visible in their skeleton. Bones and teeth are the only things paleontologists can study, but the real animal has many more parts invisible to them. For example they likely continuously evolved resistance against new diseases.