All right, so I think this is where we're going to end up. Any questions at all on that subject we talked about last time? All right, so really what he showed, or what he discovered, is that there was this descent with modification, right? And this is what gives the unity for... They have this descent with the model girl.
So some organism has a baby and then that baby is slightly different from what is from the parents, right? And because of that, there's a little bit of differences in there, but there's still this unity between all of these. They have things that are in common.
You see all these commonalities throughout the semester. And it doesn't matter what the organism is, there is a lot of reason. And then, natural selection actually acts on that as some modification. The best organisms that can survive in that environment. So, there aren't any really known things about DNA.
Basically, the individuals are suited for their environment. The time on the critiques that we... Basically, the time was, how are these traits passed down from parents to offspring?
And because we didn't know anything about genetics or DNA, we set the time, the speed that we had here, but we wanted to understand what it was like. This population of organisms, right? And there's all these variations that they have.
Too many offspring that are produced, okay? These variations are the deceptive complication. You have too many of them that are produced, right? You have all these environmental factors, these variations, okay? There's a competition because you have too many, okay?
So when we saw them are going to survive and be able to reproduce, then they passed those traits on and they're getting these evolutionary adaptations that work best in the environment. So with natural selection you do get just a bunch of very interesting adaptations that can be very useful. So you have like the bath bomb.
You can just sort of normal find that same bone. Horses have that same bone. Moles have it. We still have the same bones in the same places.
The shapes of those bones, the function of those bones are different. We've actually talked a lot about evolution up to this point, but one of the things that we haven't done is we haven't known what evolution is. So, can we ask you, what is evolution? Okay, so there's incentive and reduction.
Alright. Change in the DNA. Yeah. That's exactly what we did. So, you have a change in the genetic sequence or a change in the DNA of the population over time.
That's what evolution is. ...change in the DNA of the population over time. So, question number two. Does evolution actually happen? Would you think yes or no?
Are you going to give me 10 yeses? Alright. So my guess is, are you just saying that because I'm your biology teacher and...
But yeah, actually, evolutionary can happen. What about de-evolution? Can that happen?
Well, you sometimes hear about de-evolution. De-evolving. So you have evolution, and then you have de-evolution. So let's think about it.
Who says that de-evolution can happen? I don't know. Okay.
Who says de-evolution cannot happen? You. So the answer is really no.
De-evolution is... There's no set path. Yeah, there's no set path for what evolution is. It doesn't have a direction that it's going. So evolution is just change, genetic change, in a population over time.
And whether you, you know, if you want evolution, that's still just genetic change in a population over time. So de-evolution is really just evolution. Okay?
What about number four? Can we actually see evolution occurring? We can't see it.
It does take some time, but we can't actually see it in the real world. So, here's a Pomeranian. They're small, right?
They didn't always used to be small little dogs. They used to be kind of big dogs. Not even that long ago. So this was a painting made in 1893 of this dog. You can see that in not that long of time, there's how much they are.
Small little dogs. So that is genetic change in a population over time. So German Shepherds.
German Shepherds did not exist before the year 1899. There was no such thing as a German Shepherd before that. Into existence in 1899 by this guy. And so that is obviously a change, a genetic change in population.
Corn, for example. So plants, right? Plants also evolve. And corn, there's no such natural corn on the planet.
Natural corn does not exist on the planet. The corn, or the predecessor to corn is this plant here called chiasinte. And over many, many years, native people harvesting the chiasinte and replanting only the biggest kernels, the biggest seeds over many, many years.
There is blue corn now too, yeah. Local agriculture. crop by Native Americans in Mexico.
These people are harvesting corn. Notice the tall stalks, the large ears that grow. You can pull these off and each ear has hundreds of kernels.
Corn was originally developed by these people's ancestors who recognized the potential of a wild plant to give rise to a useful agricultural crop. Interestingly, that wild plant, Teosinte, looks very different from modern corn. So the seeds look completely different. The overall architecture of the plant also looks quite different. Wild Teosinte has a bushy-like appearance.
Corn grows in these tall stalks. So very dramatic alterations in the architecture of the plant, really all of its features, bushy or tall, and its seeds as well. That's all. No natural corn on the planet.
Here's sort of a classic example of a way of explaining, you see this as a textbook example. So you have this population of insects here, they kind of live in this dark background. There's these variations in color, right, so some of them are very dark and they blend in with the background. Some of them are, you know, lighter and so they kind of stick out a little bit.
And so those lighter colored ones get eaten by birds or their predators, that kind of thing. And then only the darker ones now that are left reproduce. And then any white ones that are left that are going to stick out for generations, in the space, are going to be much darker because they're going to match the background and stick out.
...predators in town. And then you end up with things that look like this. The mossy, mooch-tailed gecko that blends in with the street life. You can see it. You've got stuff that looks like this.
So what are these guys? Two seahorses that... Perfectly look like coral, as they are blue.
Physical appearance that is selected for, right? Really anything that is a genetic complex. You have us doing a mating dance, and this mating dance is actually, much of it is very genetic, there's a strong genetic component to this mating dance.
So if this, if one of the birds didn't know how to do this mating ritual, what are its chances of reproducing? Probably not so bad. And the train is going to be selected out very quickly.
All and only though. Pass that on to the next generation. So he looked at Finch, there are looking Finches, right?
And so he basically said that these Finches derived from an ancestor, the Finch that lives anywhere else in the world. ...niches and all that kind of stuff. And so, you can set up this tree like this to say, okay, here's the power of the ancestor, and here's kind of how they split it off into all these different types of tensions on both sides of this.
There's kind of an interesting thing, if you look in here, the next step of your work in video are going tensions on both sides. Preview question. The idea that genes are on chromosomes and chromosomes are passed on to the next generation.
That was the central idea of Darwin's theory of natural selection. True or false? False.
You didn't know anything about DNA or genetics or any of that kind of thing. That's Ritter-Mendel. The whole chapter. He was a contemporary, but he was much lesser known. Not only discovered so much later, certainly Gregor Mendel knew of Darwin.
What about this? Individual organisms can evolve. Individual organisms cannot evolve. The definition of evolution is a genetic change in the population over time, right?
So, natural selection works on the individual organism and changes the genetic population. Yeah, so one creature will have a mutation, and if that mutation is beneficial, then it can have babies and pass that on to the next generation. Alright, so what about this?
What's the difference between evolution and natural selection? So yeah, so alright, evolution is, like you said, the genetic change in a population over time. It's the mechanism by which evolution occurs.
So let's look at now, we're going to change gears, and look at basically the scientific method. So, it says here in Science and Green, bolded capital letters, every assertion regarding the natural world is subject to challenge and revision. Question everything except nothing.
Sometimes if you've heard the phrase, well, science on this is settled. For our specialties, it's never settled. The science is subtle.
It doesn't understand science, or it is deliberately lying to you. Okay? So it's one of the two.
So the science is never subtle on any thing. You should always question everything. Okay?
That's not it. So here is the scientific method. Right?
And in lab we talk about this. So if you've had lab, you've done this. If you haven't had lab yet, I've got it tonight.
We'll talk about it again. So, this is the steps, right? So, first of all, you're going to make some observations, okay? Then you're going to ask questions. Questions will lead you to answer that question, and that question is called a hypothesis.
So, choose this question. Then you have predictions, okay? And a prediction would be like a if-then statement. So, if I do this, then it should happen, okay? And you can test those predictions, test your hypothesis in controlled materials.
That is essentially the whole process. We're going through it fairly quickly here because we're going to talk about it more obviously. One thing to just kind of point out is your... These observations are not the same as these observations.
These initial observations are what make you do the experiments in the first place, and go through the scientific method. You report your findings, or you report these observations here that you find, and then these findings then become the observations for the next round of the scientific method. Okay?
That's how it works. So in lab, I focus a lot on the control experience part, testing your prediction, testing your hypothesis. So in this, I'm going to focus a little bit more on the hypothesis part. So a hypothesis is an answer to a question, essentially.
So, a hypothesis really just needs two things. It needs to be testable and it needs to be falsifiable. You need to be able to test a hypothesis. If you cannot test it, then you basically come to an end.
You can't go through science to the ground, through your spectator. So, you have to be able to test it. And then you have to be able to falsify it.
By falsify it, I mean you have to be able to show it's wrong if it's wrong. If your hypothesis is incorrect, you have to be able to show that your hypothesis is incorrect. It doesn't mean that you have to show that your hypothesis is incorrect. If it is incorrect, you have to be able to show it. So, failure to falsify a hypothesis does not prove that hypothesis.
Falsifying your hypothesis, essentially if your data support your hypothesis, that does not prove that hypothesis. In other words, Hypothesis can never ever be never. Three exclamation points. You cannot prove hypothesis, period. Because there can always be an experiment later.
So, one experiment does not prove anything. In fact, in science, you can't really prove anything. In mathematics, you can prove things, you can do a proof. In science, you cannot prove it.
So, in science, this or whatever... So laws, Newton's laws and all that kind of stuff, those are also not proven. So you have Newton's law, Newton's law, and you get a new theory.
In the 1600s when Newton had developed his laws, his common law, they were a little bit looser with their terminology back then. In the coming two years though, they just kept calling it a law. Einstein's theory of general relativity is more correct.
So, there you go. There are... Some things that are outside the bounds of science. Okay?
So supernatural explanations are outside the bounds of science. Like I said, there's a ghost. Also faith-based explanations are outside.
Why? Let's do the first one. Why are supernatural explanations?
Why is that outside the bounds of science? You can't test it, right? Because, say, well, if a ghost did it or whatever, right?
So, you're like, okay, well, let's see if the ghost does it this time. Oh, good, we want to do it this time. Okay, so you can't test it, you can't repeat it. So, it doesn't happen.
I'm not saying that either one of these is necessarily wrong, I'm just saying that you can't use the scientific method to find out faith-based explanations. Thank you. You can't falsify it, right? You must be accepted.
So, to be a hypothesis has to be testable, has to be falsified. These two reasons, right, these two things, supernatural explanations and faith-based explanations, are outside of my system. There are so much different ecstasies here.
I want you to tell me if they are a viable phenomenon. So here, this first one, there is an invisible gorilla in your room right now. Let's just stop.
How successful? Can you test for that? It is a viable hypothesis. We can quickly test it and falsify it.
But, we can say that this gorilla cannot be seen, can't be heard, can't be felt, can't be touched, but still it's here no matter what. No, because now we can't test it. So, the sky outside is gleaming with purple stars.
Is that a good hypothesis? I get it, right? Because we can go outside and we can test it. We can falsify it. Does blood pressure decrease when people sleep?
Question it. This is, okay, what about if people get sufficient amounts of vitamin C, then they won't get scurvy? Who says it's a hypothesis? Very good hypothesis. Okay.
Who says no? You said no, why not? That's a prediction. That is, that's a prediction.
It's an if-then statement. If-then statements are... So an if-then statement is a prediction, it's not a hypothesis.
Remember, a hypothesis has to be in the form of an answer to a question. Alright, what about this? Regular interaction with pets improves the health of the elderly.
Who says yes? You said no. See, I think it's not a great hypothesis.
My problem with this hypothesis is that it's difficult to test because it's not specific enough. So he said it lowers the blood pressure on the eyes, slows down the heart rate of the elderly. Okay, that's good. It just improves the health.
What does that mean? It improves the health. That means you find a little bit better to be included in the process. Excessively high temperatures cause people to act immorally.
Yeah, so you need to, again in this case, define what you mean by immoral and more specific. So if you said, causes... ...the streets or something like that. And, and yeah, so does this kind of help understand the difference between a hypothesis? What's a good hypothesis?
Alright. So, does a hypothesis have to be true? No. It doesn't need to be true, right? But, does it need to be backed up by data?
No. Not to be backed up by data. The reason it doesn't need to be backed up by data is because if you look at the order of the scientific method, a hypothesis comes... Experience.
So you do not have data yet. For your hypothesis, it really is just a best guess. Okay? So, no data necessary for a hypothesis. Okay?
This needs to be testable. This needs to be testable, falsifiable, and completely normal. Alright, so we talk about these terms, so we talk like, in just sort of normal everyday life, we have these terms, right?
I mean, we could say hypothesis, we can say theory, and just sort of normal conversation, okay? But in science, those definitions are very specific. So, in everyday conversation, a hypothesis and a theory are pretty much the same thing.
You can say law. You really need the same thing, okay? But in science, a hypothesis and a theory are very, very different, okay? So a theory is very broad in scope, okay?
A hypothesis has to be very specific, okay? A hypothesis is general enough to be used in the field. It is, in this case, supported by a large body of evidence.
So you do need data to back up a theory. So, true or false, the scientific theories have lots of data to back them up and they must be accepted and cannot be refuted. That is false, right?
Everything asks a question. I had a friend who was, when I was a postdoc, sit on the bench next to me, and he goes, yeah, I'm so skeptical, I'm not even 100% sure that the sun is going to come out tomorrow. You know, it's that kind of stuff that you've got to, you've got to be mad, and questioning everything in science.
That's what's truly about these guys. Alright, so which of the following statements here is a hypothesis rather than a theory? D, yeah. So, manner is composed of atoms.
Yes, that is definitely a theory. Living things are made of cells. Yes, that is a theory.
That is a cell theory in biology as a matter of fact. Modern organisms are descended from pre-existing life forms. Yeah, that's the theory that I'm going to show you. Female birds prefer to mate with male birds.
There is a map. Any questions on chapter 2? Move on.
Chapter 2. Chapter 2, we're going to start talking about Tennessee.