What is Evolution?

Evolution is famous. Most people have heard of it, and most people think they know what it is. But there are some popular misconceptions about it.

Okay, let's take a species. Any will do, it doesn't matter which. Now, no two of these animals are exactly the same, right? Maybe a different fur colour, or different markings, or a slightly turned up nose, or whatever. So that means that their DNA/genes (sorta like the recipe of that animal, how that animal is made) is slightly different in each individual animal. These small random[1] differences are called 'mutations' in the genes (a baby animal will again be slightly different from the mommy animal).

These differences sometimes aren't just in looks. One animal can be a bit quicker than another, or have a longer tail/better balance, or have a worse sense of smell. It can change the way the animal works/lives. If enough of these 'mutations' happen, the animal will become so different that it would be called a different species of animal.

[1] By the way, all these mutations/changes/differences (whatever you wanna call 'em) are random. I mean, you'll get most of the genes from the parents to the baby, but then there will be some little different ones that make the baby somehow different (like I said: different markings, slightly faster, etc.). We can't predict which will pop up, 'cause it's all by chance.

After many generations, some mutations spread throughout the entire population, while other mutations are still rare. Why is that? One reason is that some animals prefer mating with other animals with these mutations. So, if females of that species finds males with colourful fur attractive, it means that they'll breed more with the more colourful males, and more males in the future will have the 'colourful fur' mutation.

A more common reason is simply that some animals die because they have a mutation that doesn't work well, so they don't have a chance to pass on the mutation to their kids. If an animal has a mutation that makes it slower, it means predators have a better chance of eating it. Or there can be a mutation that makes it worse at smelling, so it can't tell if what it's eating is poisonous or not. You get the idea.

A lot of people think that 'evolving' happens to make the species better. This is so not true. What genes do is that they try make themselves as 'spreadable' and 'stick-able' as possible. Well, they don't really 'try', it just happens to be that genes that spread well and don't go away easily tend to stay with the species. Genes don't have a 'purpose' or 'try' to do stuff, it's just the way they work.

Anyway, about the 'evolution makes species better' idea: nooo. Sometimes, evolution even makes the species worse! For example, take the peacock. There was a trend in females liking large, elaborate tails (originally because a large tail generally means the peacock is healthy). So the males with bigger tails got to breed more. That made bigger and bigger tails... which, although is pretty, isn't too good for running away from foes. ... Or walking in general. >_>

This is why genes are called 'selfish'. They don't care if it makes the animal's life better or worse, it just 'cares' (remember that genes don't really 'care', they just are) about it itself being spread and replicated throughout the species.