We don't really know how flight came along. We just know that it did, and it did multiple times. [pre-post edit] I'll be sticking to non-insect flight. [/edit] There are many theories, and here's my totally non-scientific one:
It was hopping.
Feathers and stretched membrane are both used in thermoregulation and mating displays, so the things that would eventually become flight among non-insects definitely show up for their own reasons, but there's a long way to go between "I've got feathers/membrane" and "I can fly".
So how did the building blocks of flight become flight? I really think it was hopping.
A lot of people say gliding and I just don't buy that. If "flying" squirrels or "flying" fish ever develop actual flight it's going to be something totally unlike the flight we're used to in other non-insects. Truth be told, I'm not sure what flight that evolved from their gliding starts would even look like.
Moreover, I don't see a natural progression from gliding to flying. I can see it for hopping.
You've got your membrane or feathers on your limbs for whatever reason but it's not enough to let you fly. Can you use this for anything beyond what it first appeared for? The answer is, I think, yes.
Once there's enough of it to really push air, you can use it for something. You can use it to assist in hopping. The ill fated bird that I tried to save after my cat caught it and injured it couldn't do something that even resembled flying, but do you know what it could do when it tried to fly? It could hop like nobody's business.
It didn't have enough properly powered flight surface to fly, but it sure as fuck could hop on a level that could in no way be attributed to its legs.
And that's what I've always assumed came before flight. Hopping.
It makes sense to me. The building blocks of wings end up allowing animals to power hop as a complete byproduct, unrelated to the evolutionary pressures that created them, but once the animals have that power they use it and then it becomes a selective pressure of its own.
The longer one can hop the better able one is to survive, so as soon as you have wing-powered hopping you've got selective pressure that makes the best wing-powered hoppers most likely to pass on their genes. Combine that with random mutation and a metric fuckton of time and you've got animals that are able to stay in the air for longer and longer as evolution marches on, and then, eventually, you have an animal that isn't a wing-powered hopper anymore. It's an actual flier.
That's where I think wings come from. Non-flight related things have a byproduct of arms that can be flapped to extend the duration and distance of one's hop. Those with the best hop duration and/or distance survive more, and finally it reaches a point where it's stopped being hopping at all, the flapping limbs have grown so strong that they can actually achieve flight.
I have a great deal of difficulty seeing gliding leading to flight in the same way. The problem is, basically, that no matter how great of a glider selection makes one into, gliding doesn't have any inherent mechanism that would lead to power. Flight requires power.
Using flapping to extend a hop is all about power, with gliding eventually falling out (in some cases) as a side effect of the machinery developed to do that.
A flapping hop naturally points in the direction of flight, a glide doesn't. Longer and longer glides, yes, but not flight. Likewise, starting with a flap can lead to body parts well equipped to glide, but I don't see how starting with a glide would lead to body parts equipped to flap.
So there are some thoughts on wings.
[Which was the original name of this post.]
It was hopping.
Feathers and stretched membrane are both used in thermoregulation and mating displays, so the things that would eventually become flight among non-insects definitely show up for their own reasons, but there's a long way to go between "I've got feathers/membrane" and "I can fly".
So how did the building blocks of flight become flight? I really think it was hopping.
A lot of people say gliding and I just don't buy that. If "flying" squirrels or "flying" fish ever develop actual flight it's going to be something totally unlike the flight we're used to in other non-insects. Truth be told, I'm not sure what flight that evolved from their gliding starts would even look like.
Moreover, I don't see a natural progression from gliding to flying. I can see it for hopping.
You've got your membrane or feathers on your limbs for whatever reason but it's not enough to let you fly. Can you use this for anything beyond what it first appeared for? The answer is, I think, yes.
Once there's enough of it to really push air, you can use it for something. You can use it to assist in hopping. The ill fated bird that I tried to save after my cat caught it and injured it couldn't do something that even resembled flying, but do you know what it could do when it tried to fly? It could hop like nobody's business.
It didn't have enough properly powered flight surface to fly, but it sure as fuck could hop on a level that could in no way be attributed to its legs.
And that's what I've always assumed came before flight. Hopping.
It makes sense to me. The building blocks of wings end up allowing animals to power hop as a complete byproduct, unrelated to the evolutionary pressures that created them, but once the animals have that power they use it and then it becomes a selective pressure of its own.
The longer one can hop the better able one is to survive, so as soon as you have wing-powered hopping you've got selective pressure that makes the best wing-powered hoppers most likely to pass on their genes. Combine that with random mutation and a metric fuckton of time and you've got animals that are able to stay in the air for longer and longer as evolution marches on, and then, eventually, you have an animal that isn't a wing-powered hopper anymore. It's an actual flier.
That's where I think wings come from. Non-flight related things have a byproduct of arms that can be flapped to extend the duration and distance of one's hop. Those with the best hop duration and/or distance survive more, and finally it reaches a point where it's stopped being hopping at all, the flapping limbs have grown so strong that they can actually achieve flight.
I have a great deal of difficulty seeing gliding leading to flight in the same way. The problem is, basically, that no matter how great of a glider selection makes one into, gliding doesn't have any inherent mechanism that would lead to power. Flight requires power.
Using flapping to extend a hop is all about power, with gliding eventually falling out (in some cases) as a side effect of the machinery developed to do that.
A flapping hop naturally points in the direction of flight, a glide doesn't. Longer and longer glides, yes, but not flight. Likewise, starting with a flap can lead to body parts well equipped to glide, but I don't see how starting with a glide would lead to body parts equipped to flap.
So there are some thoughts on wings.
[Which was the original name of this post.]
Makes sense. There's no muscle behind a gliding squirrel/snake/fish's membranes, where all the powered flight animals have made radical adaptations to lift their weight on their forelimbs.
ReplyDeleteI'm inclined to assume that flight started out Buzz Lightyear style: falling, with style. First, with the development of the armpit-parachute, and then with adaptations for "Oh shit, I'm turned the wrong way, got to wave these armpit-parachutes around until they right me"
ReplyDeleteSeed of Bismuth said...
ReplyDeletethis! I completely agree birds are hoppers first however I should point out flying squirrels fit with proto-Pterosaur which yes our inability to picture that kind of flight is a known unknown but obviously is not impossible the way you seem to be joking?/portraying it as. Bats share the same branch with the rather less known Dermoptera/"flying lemur" showing (to me at least) that flight evolved in bats the way Ross up above states; falling with style(different to both avians & Pterosauria). This is all to say that flight may be convergent but the how and why?; very much not.