Others have said this, but the path that evolution follows is far from random. It's all based on the capabilities of a given individual to survive.

Here's a simple example that shows how quickly a positive trait can take over a localized group of creatures.

Let's assume that we have a small group of 1000 critters, that live in a stable environment that only supports a population of 1000. Because it is a stable population each member of the group has on average 1 child that survives to procreate.

These 1000 critters have some variation of course do to random mutations. Some have longer hair, some have darker coloring, whatever. Nothing major though.

Now along comes some event that slightly changes the environement over a long term. Perhaps it's an ice age. Perhaps it's a switch in the ocean currents. Perhaps its a new predator. It doesn't matter what it is, just that it changes their living environement over a significant time.

Suddenly our 1000 critters are not all equal. Let's say of the 1000 in the population now there are 50 that are slightly better suited to the new environment. Perhaps they had a slightly darker colouring and can hide from the new predator easier.

What does this advantage mean? For the purpose of this example I am going to say that it means that the 50 'better suited' critters now give birth to 1.01 offspring on average that survive to procreate, and that those offspring themselves have the better trait also.

Doesn't sound like much, does it?

Let's run the math. Assuming that the environment can still only support 1000 critters due to food constraints, space, whatever, how long would it take for this new trait to completely dominate the population?

Additional assumptions to simplify the math. Critters live 1 year and in that time they procreate once.

(initial better population)*(increase rate ^{(number of gens)}) = (population of better individuals)

50 * ( 1.01 ^{x} ) = 1000

x = log(1000/50) / log(1.01)

x = 301 or so

So after a mere 300 years, the new trait will completely dominate the population. There was no 'great plan' to make this change happen, it was just selection.

Looking at wings, as per the topic, and using Archers outline of the changes required it's not that unreasonable, I believe, to see how it happened. The points he brings up are all concerned with selection.

It's not at all like winning the lottery 1000 times in a row. It's like winning the lottery once and having 1000 kids that you teach how to win. So they change the rules of the lottery. 1 of those 1000 kids figures it out, has 1000 more kids and teaches them how to win the new lottery and so on.

We are talking about millions and millions of iterations in evolutionary time. It really hard to visuallize these vast breadths of time and the changes that they can cause.