How birds evolved the ability to fly

Okay, I'm not a paleontologist or anything, but I think I might have figured something out. I've heard a couple of theories on how birds may have evolved the ability to fly. One is that they started by gliding, either to avoid predators or to catch prey. The idea was that they would climb a tree or somthing, then swoop down to catch something. The best gliders survived the best and passed their gliding genes on to their offspring. Over the generations, the species got better and better at gliding until gliding turned into flying.

Another theory I read recently was that birds may used their wings to help them go uphill. Some scientist recently noticed that when baby birds walk uphill, they flap their wings to try to give them a little lift to help them go up faster. Since developing youngsters often go through stages that are similar to earlier forms of the species (ontogeny recapitulates phylogeny), this would seem to indicate that primitive birds might have gone through a stage where they used their wings to help them go uphill. Maybe there were climbing up a hill so that they could jump off the cliff on the other side and swoop down on some prey. :)

I think the real reason birds learned to fly was by chasing flying insects. Picture this, you've got some small two-legged dinosaur, similar to compsagnathus with strong back legs and small arms, running around trying to catch flying insects. Now this dinosaur, we'll call him Bob, is running around real fast, and this insect is flying up and down just out of reach. Bob tries to jump to catch the insect in his mouth. The better Bob is at jumping, and running fast, the better his chances for survival. Some of the adaptations that might best suit Bob's lifestyle would be to make him light weight. This adaptation would also suit his descendents as they learn to fly.

Another adaptation would be to raise his arms up just before jumping, then pull them down fast as he makes the jump. Through conservation of momentum, pulling his down will help lift his body up, allowing him to jump higher. If we assume that this dinosaur had feathers, perhaps adapted earlier for warmth, then any individual whose arm feathers stuck out a little would catch the wind with its downward arm thrusts, thus giving it even more lift.

As the generations passed, the arms would turn into more winglike appendages, and the thrust aspect of throwing the arms down would outweigh the momentum aspect, and it would become advantageous to throw the arms down multiple times to keep oneself aloft longer. This would of course turn into flying over the generations.

The main difference between birds and bats is that the thrust surface for birds is made of feathers, whereas in bats it is made from skin. Therefore, I think we can assume that if birds didn't have feathers before learning how to fly, they would have evolved wings that look more like those of bats. I know there's been a lot of stuff in the media lately about some dinosaurs having feathers, like that one found in China a year or so ago. I don't remember if that dinosaur had any kind of proto-wings, i.e. the feathers stuck out rather than lying flat agains the arms like they do against the rest of the body. Any way, that, plus the fact that the feathers on the rest of a birds body lie flat, makes me think that the feathers came first, then evolved into flight feathers to give the dinosaur additional thrust.

One possible reason for having evolved feathers is to keep the muscles warmer so that they can generate enough energy for sustained rapid movement. This would be an advantage if your prey was a fast moving flying insect, but it would also be an advantage against a lot of other prey.

If this theory is correct, it may provide an example of something else that I've thought a lot about lately. This is another subject unto itself, but I'll try to sumarize it briefly here. It has something to do with convergence, and how different species can independently evolve similar structures to solve a common problem. A prime example of this is how birds, bats and insects all evolved similarly functioning wings to accomplish flying. It is generally assumed today that each of these "flying phylums" developed these capabilities independently, but what if that's not the case. Certainly the genes for wing structure can't be passed from an insect to a dinosaur, but the idea for flying can. Insects learned how to fly first, I think that's pretty well established, and I think, therefore, that they deserve the credit for "inventing" flying. Birds learned how to fly next, and I think they've been given credit for inventing the ability to fly all on their own, but if my theory is correct, they really kind of get the idea from insects.

Anyway, like I said, I'm not a paleontologist, and I don't have time to really chase down this theory. There may already be stuff that's been found that disproves this theory and that I'm simply not aware of. Or, it's possible that this is already an established theory and that I simply haven't heard of it yet, or heard of it so long ago that I've forgotten it. However, "hope springs eternal", and I'm hoping that this is a new theory, so I'm documenting it here on blogger, along with a time stamp. I came up with this theory while driving home from work last Friday night (I think about a lot of stuff while driving home), Feb. 27, 2004, at around 6:00 PM, Pacific Standard Time.

The Evolution of Religion

I've often wondered how we evolved the capacity for religion. This morning, on the way to work, I was listening to something on KPBS about voodoo, and it got me thinking about this again.

During the radio report, they played back part of an interview with a woman who was supposedly the bride of the demon of smallpox, or something like that ("demon" might not be the right word here, but I can't remember his name or exactly what they called him). She said that the demon protected her and her family. She said that when she had to start selling rice in the market, she prayed to the demon and he gave her good luck.

It occurred to me that believing that this demon could help her probably allowed her to go to the market with more confidence, especially the first time she went, and that this may have enabled her to do better than if she had to go there without his protection. In terms of evolution, the capacity to believe in a deity that could help her improved her chance of survival, and the chance of passing on this characteristic to later generations.

The radio show went on to say that a major component of a lot of African religions is that of ancestor worship. They described how someone might invoke the spirit of a dead grandparent to get advice on a certain issue. How could something like this give someone a selective advantage?

I remember once in college, when I was doing homework in the library, struggling with a particular problem. I was considering going and asking the professor for help. As I sat there thinking about it, I pictured myself asking him a question about the problem, and then I pictured him answering the question. The answer he gave made sense, but it didn't completely answer the problem, so I pictured myself asking another question, and getting another answer. In this way I was able to solve the math problem. The point is that the ability to answer the question was in me all along, but that picturing how the professor would answer my questions provided a mental pathway for me to find the answer.

In tribal life, you often go to the elders for advice when faced with a problem. But what happens when those elders die. Suddenly your faced with problems that you need to solve yourself. Maybe you can, but for particularly hard problems, it may benefit you to picture asking the elder for advice, and then picture the response. One way to do this would be to invoke the spirit of the dead elder and ask it. The belief that the spirit is real and that you are really asking the elder for advice will help enhance the experience and make it easier for you to picture a response. This will be an aid to your survival and, again, natural selection would select for those individuals who posess this belief.

An another benefit of ancestor worship is that, since you're picturing getting advice from a respected elder, the advice that you 'get' is likely to be in the similar to what the elder really would have given. In a tribe, this helps the continuity of the leadership of the tribe, keeping it going in the same direction that it was going before. Since you're only going to ask advice of the spirits of elders whose advice had been respected in life, this is kind of a way of training new leaders to lead in a way that has been proven successful in the past. This makes the tribe stronger, improving the survival chances of its members.