Clear the Mud

An email was sent to PZ Meyers, a prominent researcher and vocal opponent of anti-evolutionists. The question subtly shocked me and yet didn't surprise me at all:

How does a tree know how to "evolve" it's seed to fly on the wind?
How would a lizard "know" that it needed to develop camouflage to
survive?

I can't imagine who any plant or animal other than human would have
the ability to "know" and as well as pass it along via DNA to future
hundreds of thousands of generations?

The super-quick answer, by the way, is: No one knows or thinks about needing to "evolve". No more than hydrogen "knows" how to condense into stars or we "know" how to grow from baby to adult.

All things follow some combination of rules: of Physics/Mathematics, of Chemistry, of Biology.

In the case of natural selection, the rules, in their most direct form, aren't that complicated once they are spelled out.


Also, the question is a fair one. But only in a world where few understand the basics of biology. There's a lot of people that share blame for this - scientist and non-scientist alike. But the fact is, it is a situation that now exists which needs to be addressed.

And - I really, really want to point this out - not knowing a thing is NOT something to feel bad about, especially when you're willing to ask questions. Yes, there's occasionally some stuck up snot who'll lord his or her pool of knowledge over you like it was a badge of honor. But that's because they are jerks.

Knowing what you don't know, and asking to find answers, is how everyone learns.

So, as I tried to do in a comment on that post... I want to try a simple summary of the concept of natural selection: Feel free to tell me if I have screwed something up here, by the way.

1. We're all random mutants:
(Which I touched on in part 1 and part 2)
Essentially every animal, plant, or whatever, is born with a number of mutations. Many, if not most, of which don't do much one way or the other. Additionally, which particular mutations each one has is basically random. One will have a mutation in this part of the DNA instructions, another will have a mutation in a different spot of the instructions, and so on.

2. Natural challenges are thrown at populations all the time:
(Which I touched on here in general and here with a specific case)
Nature constantly throws challenges at populations: Way too hot, too cold, lack of food, too many predators on the ground, a poison or toxin seeps into the environment, lake water levels shrink, water levels rise and invade areas that were once land, a massive eruption drastically alters the environment of the planet, an asteroid strikes ... really just think of something bad, and it probably already happened more than once in the world. And these are just the really drastic ones. More subtle challenges - many at any given time - happen pretty much continuously.

3. Any given challenge of nature makes some DNA mutations more beneficial than others:
If individuals have DNA changes that allow them the ability to thrive better under the conditions created by natural challenges, then they and their descendants will carry those changes forward. Those that have less ability to thrive under those conditions will be lost and take their genes with them.

4. The longer the challenge lasts, the more the beneficial changes set-in and develop:
Sometimes a severe natural challenge arises but only briefly (imagine there being a horribly bitter winter one year which really takes a toll on all the animals in an area. But then for many years afterward, the winters return to normal). In these cases, while the genetic changes - say an increase in hairiness - may have helped some survive over others, the removal of the severe pressure removes the need for that specific changed DNA.

The longer a specific challenge lasts (for example, it's not just cold for a winter, but a new ice age begins) the more this selective filtering will happen. First, the ones having the original beneficial mutation will remain the most able to survive. Then, as new mutations occur, there are new random DNA tweaks.

Again, while the new mutations are random (as they always are), it is the tweaks that continue to improve survival within this prolonged stressful environment that will endure in favor over the others - even over the tweaks that FIRST allowed them to survive. The longer this pattern continues. the more apparent the physical changes - ones that have become continuously better at their special function - will be.

5. No one knows this is happening to them:

All of this is due to constant pressure - to be more warmer, more able to hop or fly from tree-to-tree, more able to see better, run better, etc, etc. And it's all happening under all all our noses. Even we humans, with the ability to think in detail, don't know the environmental challenges that will be thrown at us tomorrow and which particular traits will help us get through them.

No one knows it's "time to change". Change happens. And sometimes a useful change happens at the right time. And so the change sets into the population. But, rest assured, no one is aware of it. What they - we - are aware of is that we are living our lives the best we can.

And that's enough of a responsibility right there. without worrying about "how to evolve". Frankly, I'm happy I don't have to worry about that.

I've got enough on my plate as it is.