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In the first video on evolution, I gave the example

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of the peppered moth during the Industrial Revolution in

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England and how, before the Industrial Revolution, there

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were a bunch of moths: some were dark, some were light,

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some were in between.

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But then once everything became soot filled, all of a

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sudden, the dark moths were less likely to be caught by

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predators and so all of the white moths were less likely

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to be able to reproduce successfully, so the black

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moth trait, or that variant, dominated.

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And then if you came a little bit later and you saw all the

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moths had turned black, you'd say all

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these moths are geniuses.

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They appear to have somehow engineered their way to stay

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camouflaged.

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And the point I was making there is that, look, that

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wasn't engineered or an explicit move on the part of

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the moths or the DNA, that was just a natural byproduct of

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them having some variation, and some of that variation was

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selected for.

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So that example, that was pretty simple: black or white.

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But what about more complicated things?

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So, for example, here I've got a couple of pictures of what's

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commonly called the owl butterfly.

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And what's amazing here, and it's pretty obvious, as I

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probably don't have to point out to you, is its wing looks

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like half of an owl's eye.

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I can almost draw a beak here and draw another wing there

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and you can imagine an owl staring at us, right?

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And here, too, I could imagine a beak here and you would

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think an owl there, too.

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And so the question is how does something this good show

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up randomly, right?

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I mean, you could imagine, OK, little spots or black and

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white or grey, but how does something that looks so much

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like an eye generate randomly?

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Now the answer is-- well, there's a couple of answers.

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One is why does this eye exist, or this eye-like

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pattern or this owl-like eye's pattern?

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And there, the jury's still out on that.

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I read a little bit about it on Wikipedia and all of these

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images I got from Wikipedia.

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In Wikipedia, they said, look, there's two

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competing theories here.

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One theory is that this, even though to us humans, the way

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we see things, it looks like an owl's eye, that this is

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actually a decoy.

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When some predator wants to eat one of these things, they

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go for the thing that looks most substantive.

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So instead of going for the butterfly's body, which

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doesn't look that substantive, they go for

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the big, black thing.

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They say, oh, that looks like it's protein rich and it'll be

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a good meal.

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So they try to snap and bite at that, and if they bite at

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that, sure, the guy's wing's going to be clipped a little

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bit and it's going to suck, but the animal itself, the

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actual butterfly, would survive, and maybe it can

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repair its swings.

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I don't know the actual biology of the owl butterfly.

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That's one theory, and then the argument against it goes,

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well, no, if that was the case, then you would want the

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black spot even further back along its-- you'd want the

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spot way far away from the body.

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You'd want it back here instead of right here, because

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there's still a chance, if something chomps at this

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little black spot, that it'll still get the

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abdomen of the butterfly.

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Now, the other theory as to why this exists-- and, you

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know, who knows?

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Maybe it's a little bit of both.

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Maybe both of these are true.

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Maybe this offers two advantages.

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The other theory, and this is kind of the one that jumps out

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at us when we see this , is, hey, this looks like an owl.

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Maybe this is to scare away the things that are likely to

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eat this dude.

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And it does turn out in my reading that there are lizards

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that like to eat these type of butterflies, and those lizards

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probably don't like to be around birds or owls because

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those owls eat them, so that might be a deterrent.

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And then the other example, they said is, look, they tend

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to be eaten by this lizard right here-- this is what

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Wikipedia told me-- and that this lizard tends to be eaten

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by this frog right there, and that the eyes of this

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butterfly are not too dissimilar to the

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eyes of this frog.

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And, you know, we can debate whether or not that's the

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case, and if this was the predator we're trying to

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mimic, you could make an argument that maybe we would

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have had more green on our wing, but that's not the point

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of this video.

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But it's a fun discussion to have as to what is useful

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about this eye.

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But let's have the question: How did that eye come about?

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And when I say that eye, I mean the pattern on that wing.

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What set of events allowed this to happen?

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Because when I described evolution, and we know that

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everything in our biological kingdom is just a set of

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proteins and then stuff that maybe the protein-- but mainly

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protein, and that protein's all coded for by DNA.

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I'm going to do future videos on DNA, but DNA is just a

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sequence of base pairs.

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It's a sequence of these molecules.

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And we represent adenine, and guanine and

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cytosine and thymine.

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Then maybe you have a couple of adenines in a row and some

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guanine and thymine.

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I'll do a lot more on this in the future, but the idea is

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it's just coded for by this sequence of these molecules.

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How do you go from a butterfly that has no eye to all of a

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sudden an eye that goes there?

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Obviously, just one change that happens

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from a random mutation.

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Maybe that G turns into an A or maybe this C and this T get

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deleted so everything-- that alone isn't going to develop

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this beautiful of a pattern or this useful of a pattern.

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So how do the random changes explain

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something that's this intricate?

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And this is my explanation.

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And obviously, I wasn't sitting there watching over

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the thousands or millions of years as these owl butterflies

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emerged, so this is just my theory of how natural

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selection does explain this type of phenomenon.

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You have a world where in some environment you have

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butterflies, and their wings look like-- let's say you have

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some butterflies that are generally like this.

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That's their wing, and it's a very bad drawing, but I think

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you get the idea, and there's just some general patterns.

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We've seen it before.

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There's variation.

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And the variation does show up from these little random

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changes in DNA.

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I think we can all believe that, that most of these

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changes are kind of benign.

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Maybe they just set up differently where a little

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pattern will show up or a little speck of pigment will

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show up with a slightly different color.

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And we even see amongst these owl

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butterflies, there is variation.

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This dude's wing is different than that guy's wing with the

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commonality that they do have these eye-looking shapes.

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And there's not just one; there's actually multiple.

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This guy has this other thing up here that looks

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interesting, and they have multiple things, but the one

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really noticeable feature is this eye-looking thing.

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So how do we go from this to an eye-looking thing?

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So the idea is you have some variation.

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One guy might look like that.

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Another guy, or gal, might-- just randomly, their dot might

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be something like that.

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Another gal or guy-- these wings are really badly drawn,

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but you get the idea.

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This is the butterfly.

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This is its antenna right there.

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That's its body.

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Another butterfly's patterns might look like this, right?

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And so, they're just random.

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But when they go into a certain environment for

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whatever reason, maybe one of its predators-- maybe that

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theory that these are supposed to look like eyes is true.

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And so, actually, maybe this guy just has a

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random pattern here.

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And so this guy-- and I'm not saying that it's like

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definitely better.

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They're both going to be found and killed by predators, but

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it's all probablistic, right?

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Maybe this guy has a 1% less chance of getting a predator,

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because when a predator just looks at him out of the corner

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of that eye, that little really hazy region kind of

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looks like an eye and the predator would be better off

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just not messing with it, and they'd rather go after the

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dude that looks like this.

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So it's just a slight probability.

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Now, you might, say, OK, what's 1% going to do?

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But when you compound that 1% over thousands and thousands

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of generations, all of a sudden, this trait might

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dominate because he's just going to be killed that less

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frequently, 1% less frequently.

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Now, maybe this guy has a similar trait, but his spot is

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closer to the abdomen.

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And here, it's a tradeoff, because maybe some predators

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get scared away by this concentration of pigment.

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And once again, I'm not saying that we're here yet.

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We're not at this very advanced, sophisticated

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pattern yet.

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We're at this random concentration of pigment that

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just shows up.

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So we see that people who have this concentration of pigment

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further away from their abdomen, they do well.

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But when it's too close, maybe some predators think that

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that's actually an insect and they want to eat it, so that's

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actually a bad trait.

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So what happens is this guy dominates, and so within this

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population, you start having a lot of variation, because he

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starts representing-- he's more likely to

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pass on these traits.

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And I want to make that point very clear.

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This isn't what happens over the course

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of an animal's lifetime.

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It's not like if somehow I experience something, or at

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least our current theory if I experience something, that I

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could somehow pass on that knowledge to my child.

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What it says is if my DNA just happens to have just some

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variation that happens to be more useful or more likely for

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me to survive to reproduction and for my children to

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survive, then that will start to dominate in the population.

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So then the population, you're going to have variations

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within that.

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Maybe some guys, you know, it's going to get a little bit

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to look like that.

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Maybe another one's going to look a little bit like that.

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Maybe it has some spots there.

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You can kind of view it as the variation as "exploring." But

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I want to be very clear not to use any active verbs here

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because this is all being done really as almost a common

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sense process, where everything changes.

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The changes that are most suited are the ones that are

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going to survive more frequently.

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And then the next generation's going to have more of that and

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then you'll have variation within that change.

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And then this one might be like that, and

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maybe this is the one.

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These were good compared to that, but now when you're

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competing amongst themselves, this one is able to reproduce

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1% more than this guy or this guy.

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And so this guy becomes-- and maybe it's some combination of

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all of the above, and they mix and match.

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It's a hugely complex system.

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But then this guy represents most of the population, when I

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say this guy, I'm saying this guy's genetic information, at

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least as it pertains to his wings.

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And then you get variation amongst that.

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Maybe some of it, they have a little small dot and there's

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some dots around it.

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Maybe it's like this.

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Maybe one of them digresses and goes back here, but then

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he has trouble competing so he gets knocked out again.

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And then some other people have it back here.

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I think you get the point that this

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isn't happening overnight.

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These changes can be fairly incremental, but we're doing

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it over thousands of generations.

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So when you're talking about thousands of generations, or

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even millions of generations, even a 1% advantage can be

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significant, and when you accumulate those variations

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over a large period of time, you can get to fairly

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intricate patterns like this.

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So I just wanted to explain that, because this is often

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used as, sure, I can believe the butterfly moth or I can

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even maybe believe the examples of the antibiotics

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and the bacteria or the flu, because those are kind of

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real-time examples.

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But how does something this intricate show up?

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And I actually want to make a point here.

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We think this is more intricate because we can

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relate to it in our everyday lives.

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But if you actually look at a structure of a bacteria and

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how it operates or what a virus does to infiltrate an

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immune system or a cell, that's actually on a lot more

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levels a lot more intricate than a design.

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In fact, the whole reason why I'm using this as an example

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is because this is a fairly simple example as opposed to

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kind of explaining the metabolism of a certain type

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of bacteria and how that might change and how it might become

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immune to penicillin or whatever else.

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But I want to make this very clear that these very

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intricate things, they don't happen overnight.

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It's not like one butterfly was completely one uniform

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hot-pink color and then all of a sudden they have a child

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whose wings looked just like this.

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No!

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It happens over large periods of time, although there might

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be some little weird hormonal change that does this, but I'm

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not going to go there, but that is possible.

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But I just wanted to make this point because I think the more

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examples we see, the more it'll kind of hit home that

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this is a passive process.

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We're not talking about these things happening overnight.

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And it's actually really interesting to look at our

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world around us and look at ecosystems as they are today

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and try to think really hard about how something came to

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be, what it's useful for, why it might have

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been selected for.

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For example, are traits that occur after reproduction

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selected for?

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Well, probably not unless they affect the reproduction of the

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next cycle.

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For example, you might say, oh, well, the trait to be

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nurturing after your reproductive years, that's

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after reproductive years.

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No, but it helps your offspring reproduce.

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But we already see a lot of diseases, especially once we

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get beyond our reproductive and our child-rearing years.

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So once we get into our fifties and sixties, the

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incidences of diseases increases exponentially from

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when we're younger and because they're no longer being

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selected for, because it no longer affects our ability to

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reproduce, because we've already reproduced.

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We've already raised our children so

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that they could reproduce.

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So the only thing that happens at that point is now not being

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selected for.

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So anyway, hopefully, this video will give you a little

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bit more nuance on evolution, and I want to do a couple of

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videos like this, because I really want to make it clear

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that it's not making some wild claim that all of a sudden

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this appears spontaneously, that it really is a thing that

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happens over millennia and eons and very gradually.

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