Why did the fish things crawl out?

[Kozmos]

I am watching David Attenboroughs Life In Cold Blood series of documentaries and drinking and it got me thinking, why did the fish-reptiles-whatever leave the water to go on land? Now the shows say the land was crawling with insects by this point so it was a matter of plentiful food, but why not stay inside? Develop a nice aquatic civilization, much more resistant to extinction events and what-not.

 

[warpus]

You answered your own question, I think. There was more food there and no predators. There would have been a huge evolutionary advantage for any organism that was able to take advantage of that ecosystem.

And it's not like an entire species decided to crawl out one day. It was an incredibly slow process that slowly gave preferencial treatment in terms of survival to organisms that were better able to use those resources on land. The crawling happened at some point in this process, but that's not how it started, I don't think. (I could be wrong about this part)

 

[History_Buff]

Yeah, plentiful food, few to no predators. Animals still come into cities today for that.

As for mass extinction events, it's not like they were planning ahead. They would have had no way to know that was a thing, or whether it could be limited to just the land. It's kind of a dumb argument really.

 

[Kozmos]

I know, I'm just miffed we haven't ran into an undersea empire ruled by sentient sea slugs or something.

 

[warpus]

I know, I'm just miffed we haven't ran into an undersea empire ruled by sentient sea slugs or something.

This is just a guess, but it's far harder to use tools effectively underwater, especially if you have fins, instead of digits.. and underwater life just sort of evolves things that allows them to move in the water better - this doesn't easily lead to fingers like we have - and thus makes it harder for any creature to use tools. There's some examples I think, but they are limited. There is also no way to create fire, so even if you ended up with an extremely intelligent creature like an uberdolphin, it'd be hard to see a kingdom develop or whatever. Things also erode a lot quicker in water, meaning that any sort of structure sea-bound creatures could build would just not last nearly as long as the things we build up here. There are just many limiting factors and I'm sure it's possible, just much more unlikely than sentient life up here.. and look how many times it's happened here. It's probably somewhat unlikely up here on land as well.

 

[Winner]

Yeah, plentiful food, few to no predators. Animals still come into cities today for that.

This makes me wonder what kinds of selective pressure is the human civilization imposing on these animals...

 

[kramerfan86]

Life and evolution is all about filling a niche. Sure you can be doing fine in your current niche, but competitively in terms of passing on your genes you can do even better in an unfilled niche.

 

[Lord Baal]

This makes me wonder what kinds of selective pressure is the human civilization imposing on these animals...

We've certainly affected the evolution of several creatures, some of them specifically (dogs, cats, livestock) and some of them accidentally (thylacines, those mutant frogs near Hiroshima). We can't really quantify the effect our species has had on the evolution of other species; all we can really do is try to limit any future damage. Not that we seem to be trying that hard.

 

[Kyriakos]

Some didn't. For example i have read that an underwater colony of fish-things existed at some point near Innsmouth.

 

[MagisterCultuum]

A commonly accepted theory is that the first land vertebrates did not so much crawl out of the water as find themselves stranded there accidentally. Sea creatures living near the shore might be left exposed when the tide withdrew, and creatures in ponds or streams might have their homes dry out completely during droughts. The ability to move around on land would have initially been most useful as a means of getting back into the water.

 

[Berzerker]

some critter with a gill mutated a lung

 

[emzie]

Natural selection has no foresight. Nothing decided to crawl out of the oceans. When our ancestors did find themselves in transition between the two, it became very advantageous to exploit the virgin world of land. You can't think of evolution except in the context of the moment in history. What actually came after is irrelevant, as future situations don't factor into natural selection.

some critter with a gill mutated a lung

Stop learning biology from Pokemon. Lungs didn't develop from gills.

 

[Aleksey_aka_al]

Scientists should modify dolphins to have hands. Then let the creatures think on the part of a nice aquatic civilization, build it and prosper, so that later humans could enslave them and rule the undersea!

 

[Leifmk]

Scientists should modify dolphins to have hands.

This would probably just result in a lot of masturbating dolphins.

 

[Winner]

We've certainly affected the evolution of several creatures, some of them specifically (dogs, cats, livestock) and some of them accidentally (thylacines, those mutant frogs near Hiroshima). We can't really quantify the effect our species has had on the evolution of other species; all we can really do is try to limit any future damage. Not that we seem to be trying that hard.

Well, I am wondering about all these semi-wild animals (badgers, foxes, raccoons, birds, rats, etc.) which are drawn to the cities. They should show some adaptation to the urban environment pretty quickly (though that still may be too slow for us to notice, evolutionary timescales are outside our purview).

I was wondering when certain animals which get regularly killed by cars on account of their freezing in the headlights evolve more useful responses - the selective pressure there is quite significant.

 

[FriendlyFire]

I know, I'm just miffed we haven't ran into an undersea empire ruled by sentient sea slugs or something.

No fire = no tools = no civilization

 

[schlaufuchs]

Well, I am wondering about all these semi-wild animals (badgers, foxes, raccoons, birds, rats, etc.) which are drawn to the cities. They should show some adaptation to the urban environment pretty quickly (though that still may be too slow for us to notice, evolutionary timescales are outside our purview).

I was wondering when certain animals which get regularly killed by cars on account of their freezing in the headlights evolve more useful responses - the selective pressure there is quite significant.

It would be interesting to see, but I just don't think any of those things will be a Thing long enough for phenotypically apparent trends to manifest (aside from extinction, obviously).

 

[Aleksey_aka_al]

No fire = no tools = no civilization

And for what reason would ancient apes need a fire?

 

[Dachs]

Natural selection has no foresight. Nothing decided to crawl out of the oceans. When our ancestors did find themselves in transition between the two, it became very advantageous to exploit the virgin world of land. You can't think of evolution except in the context of the moment in history. What actually came after is irrelevant, as future situations don't factor into natural selection.

I've always wondered about this: how does that actually work? I mean, lots of different things have to develop at more or less the same time for a change like "becoming a land animal" to work. Most creatures would need to change the way they breathe, their method of locomotion, probably the way they see, and so on, and if only some of these changes happen, they're worse than useless. Or, like, echolocation: how does that develop, when the ears, the brain, and the vocalization all have to change at the exact same time, or else there's zero advantage?

 

[Antilogic]

To die in the name of science.

More serious answers tomorrow.