Flight

OK I guess I basically have some understanding of the concepts of evolution and it generally makes good sense, but when I think about something specific, it is more difficult to understand. Flight, for example, how did flight start? Lots of theories are around, most seem to be simply that theories based on the possible, with little evidence.

Flights seems like such a binary thing. Either the bird can or cannot fly. How do you go from arms to wings or even gills to wings, in the case of insects?

There is evidence about adaptions once flight has been achieved and it is easy to image how selection improvements might improve flight.

There are plenty of theories about what happened and why it happened. But how did it happen really? What is the process by which a gill becomes a wing. It would seem to be a multi- generational set of changes that are more that random genetic variation. What forces where at work? What are the intermediate stages. It occurs to me that for Evolution to be successful all the variations that ultimately lead to flight must also be beneficial in their own wright. That is if, say full flight is 10 generations from gills in a insect. Each of these generations must have been at least moderately successful. Successful enough to be able to ensure survival to the next generation.

Can it really be that animals descending of trees developed gliding and ultimately wings? Fossel records seem currently to be missing the transitional species that would provide the clue to the path taken to flight. Why are these transitional species missing? Is is because in fact fossel records are extremely incomplete? Is if that these transitional species existed for only a short time?

More I think about this the more mystifying it appears to be. Evolution must certainly be a complex and amazing process.


http://www.ucmp.berkeley.edu/vertebrates/flight/converge.html