Flagellum Motor:Is this Scientific?

[AFJ]

Yes, biohazard. I agree with you. it's like looking at the weather in 2D when it is a 3D system. But the point I see here, that you may not agree with, is that NS is not directional, but evolution is supposed to be. To say that NS is directional is to say that the proper sequence of environments just so happened to keep things in direction from less to more complex life. Even though I personally see the "least" complex life as too complex for us--that is we can't figure out how to make it ourselves, though we've tried.

[canalon]

No AFJ, NS is certainly not directional. It seems to go toward mor complexity, but it is in fact a simple artifact. Were you to look at the distribution of complexity (measured one way or another) vs number of organisms (or even species or OTU) you would see a distribution extremely skewed to the left. Because life entails a minimum complexity below which it cannot maintain it self (at least in today's conditions), but no maximum for complexity. So there are tons of bacteria and relatively much less tetrapods.
Many parasites are showing that selection can also go toward less complexity in the right conditions with the loss of multiple functions provided by their hosts.

[alextemplet]

NS is not directional, but evolution is supposed to be

Neither NS nor evolution are directional. Organisms adapt to survive in whatever environment they happen to be at the moment; they are not concerned with what "direction" they are heading as long as they can survive and reproduce.

[biohazard]

...

That parasites part was an excellent example about the bi-directional nature of evolution and NS. It is also interesting to think whether (some?) viruses have also evolved in a similar manner: they were originally more complex, but they've given up every part from their structure whose function the target cell can replace, and eventually only nucleic acids and some accessory structures remain nowadays.

If that was true, natural selection would've made something that was living essentially dead but still functional :)