Yeah but what IS evolution?

I first heard the word "evolution" in second grade, when I was introduced to Pokémon for the first time. It took me years to realize it was anything more than a level-up system in a game. But joke's on me, because evolution isn't a level-up system in a game. It's a level-up system in real life. 

Think about it. Evolution is, at it's core, change. It's really slow change, because it doesn't happen to just one individual (sorry, Pokémon). Evolution happens over time within a lineage of individuals, as each offspring is a little different from their parents, and passes on their differences to their offspring, who are even more different. So it takes a relatively long time (depending on what kind of thing is changing) for evolution to do anything noticeable on a large scale, because you have to wait generations and generations to see this change spread from one individual to an entire group of individuals. But that change, from a group being one way to a group being another way, is evolution. 

Of course, there's one more important question: who decides which changes happen? Long story short, the environment itself decides which changes happen. A bunch of different possible changes pop up all the time in different individuals. Some of these changes are bad. Some are good. The good changes are the ones that help an individual survive in their environment. The bad ones hurt an individual's ability to survive in their environment. Thus, the individuals with bad changes aren't going to survive as long as the individuals with good changes. Eventually, all the individuals with the bad changes are gone, and only the individuals with the good changes are left. And since these changes get passed down from parent to offspring, eventually every individual is going to have those good changes that they got from their parents. 

I call evolution a real-life level-up system because it helps groups of individuals (populations, as they're formally known), better adapt to the environment they live in. Of course, "level-up system" isn't a perfect analogy; evolved individuals aren't inherently stronger than the original species they came from. They're just adapted in a different advantageous way. 

A really smart guy called this complex system "Descent with Modification". He also proposed the theory of evolution. His name was Darwin; maybe you've heard of him. But the "theory" of evolution isn't as theoretical as you might think. 

Let me explain. About 200 years ago, an old guy said "What if species changed over time?" And everyone else was like "...bro." But they didn't really like it, because this old guy didn't quite get the mechanism of changes right. Fast forward to a few decades later, and two OTHER old guys were like "...What if that old dude was right, but also not quite right?" and this time, people were like "...bro," but in a good way. Those dudes were named Darwin and Wallace; they both came up with the theory of evolution on their own almost simultaneously. Buuuut Darwin got his published first, so he gets the credit. 

Anyways. Darwin's "theory of evolution" isn't a theory in the colloquial sense. Oftentimes people will use the word "theory" to indicate they have a hunch or guess. You might say, "I have a theory that my friend will like Swedish fish, because they like gummy bears." But Darwin, and indeed many scientists, don't use theory like that. Darwin's "theory of evolution" is a scientific theory. Which basically means that we have lots and lots of solid evidence of how a thing works, because we've tested it over and over again. Newton's "theory of gravity" and Einstein's "theory of relativity" work the same way. Any kid who's fallen over knows that gravity exists, but it's still called a scientific theory because it's a well-supported explanation of how the world works based on experiments and evidence. 

As I'm writing this out, I'm beginning to wonder if I somehow ruined Michi's assignment, because I didn't really decide whether evolution is a theory or a fact. I kind of decided that it was...both. I'm also beginning to worry that I didn't remember what a scientific theory is correctly, because I haven't read the book that introduced the idea to me in a long time. Buuuut, that book is at my parent's house, so I'm just gonna wing it. If I'm wrong, I'm wrong. All that matters is that I write with more confidence than I feel. Sorry, Michi!