Before we really dive into evolution and natural selection, we just want to think about how we talk and think about organisms. And so this is going to lead us to contrast two types of thinking: typological and population thinking. So let's start out by talking about typological thinking. Typological thinking is when you have sort of one ideal or one sort of idealized form to which we compare other things in the world. And this is an idea that sort of came from Plato, the ancient Greek philosopher.
And when we think of that one ideal, when we go out into nature and we see variation, well, we're going to think of variation as a deviation from that ideal. All right. To give an example of this, we're going to look at some lions. So if I sort of picture a lion in my head, this is kind of my idealized form for a male lion. But of course, if you go out into nature and you look at lions, you're going to see that there's actually a lot of variation out there.
These are all sort of variants of manes of lions. You have some that have dark manes, some big old dark manes that go way under their belly. You have some males that actually don't grow manes at all. So typological thinking says, well, all this variation, that's not really what a lion is. A lion is this idealized form, and those variations, that's just sort of a deviation from that ideal.
Now, if we take this approach, that means that a species description is going to be unchanging over time. And importantly, it does not include its diversity. All right. So now let's contrast that to population thinking. Well, in population thinking we're going to start out by saying that variation from all individuals is important.
So now if I wanted to find what a lion is, I don't think of, you know, in my mind's eye, what is a lion. I need to go out and I need to find all the lions or at least the representative subset of lions. So I start with the group of lions, and I look at all this variation. And that's how I define my species.
Now from all this variation, I can take an average, and I might get an average and say okay this is my average lion. But we want to be really clear here. What is average in population thinking? Was average or typical? It depends on the variation.
Right? There is no lion that is average in every single way, that is typical in every single way. This average lion in population thinking, it's really more of a statistic. So when we use this way of thinking, well, yeah, we can have an average, but we acknowledge that the variation is real. This means that a species description will change over time and very importantly includes its diversity.
All right. Now you may look at this and say, like, okay. Yeah. Well, that makes sense. Why would we ever do typological thinking?
But we do forms of typological thinking a lot. It's a common way to think, and it's a common way to think in biology. Now when you hear in genetics when we say something like the gene for hemoglobin or in physiology when we say the human heart, we're usually thinking of sort of a single standard form of that and not really worrying about the variation at that time. Now that's a typological way of thinking that helps us out because we really just want to understand how these things work at one level, and we can worry about the variation later. But for evolution, it is really important.
To understand evolution and natural selection, we must use population thinking. We must focus on that variation. All right. Examples and practice to follow. I'll see you there.