 Hi. Just in case you're wondering, this is a general biology course. And so biology is the study of life. This is our first content-based lecture that we are going to engage in. And our whole purpose in this lecture is to define, dude, what are we going to study in this entire class? And the answer is life, because biology is the science of life. Now, I feel like, dude, I hit the jackpot, because I, being a biology instructor, is like the coolest thing ever, because you get to learn all about living critters, and there's like, whoa, it's going to blow your mind how many different kinds of living critters there are. And really, I mean, we're going to start this whole thing off by going, well, what is a living critter? What is life? How do we know if something is actually alive or not? It's kind of surprisingly a baffling question, because I think that everybody is like, dude, I know what's alive and what isn't alive. For example, this very lovely little, I think it's a pigeon. This very lovely little fancy pigeon. Don't you like want one of those? It looks all cute and fluffy and cute. Don't you like its hair? Okay, they don't, it's not hair. It's a feather, because it's a bird. It has a little head thing that looks really cool. You know it's alive, right? And if it fell down, you would know that, okay, it's probably dead now. And it's not something like it doesn't take you a long time to figure out if something is alive or not alive. You know that, dude, even though a waterfall is moving, the water is moving over all these rocks, you know that the water itself isn't alive. How do we know this? We just kind of have an intuitive sense. We know that this thing, talk about great hairdo, this is some awesome squirrel that had, that this thing has hair, because it is a mammal. But look at those ears. Dude, that's awesome. And then even to things like this is an animal, it's a little bit less like cute and cuddly, but it's really pretty. And in fact, this little jelly-friendly jelly friend has eyeballs, well, eyeballs. It has eye spots all over it for picking up light. The study of life is so diverse and so cool, and we could literally spend an entire semester on every single day's topic in this course. Before we dive into all the coolness, which is inevitable, we must do. We must dive into the coolness. We need to kind of like figure out, okay, what is it, what are the characteristics that help us determine that all those things that we just looked at are actually alive? And there are five characteristics that in general people have agreed that if something has all of these characteristics, then it probably is alive. However, it's a little bit tricky because life is something called an emergent property. I'm going to write that down for you. Let's define an emergent property, an emergent, emerging. That makes me think of like something that's coming out of the swamp. Like the swamp thing is emerging out of the murky swampy murk. And you didn't know that it was there before because it just looked like a swampy murky murk. But now the swamp thing is there, and it emerged out of there, whatever. An emergent property is a property that didn't exist before, but when you put together several pieces, several parts, you get this new thing. Life is an emergent property that comes out at the cellular level of organization. So before you put parts and pieces together to get a cell, things are not alive. Things are only alive if they have a cell as part of their makeup. An emergent property, you know, cells are made out of proteins and fats and nucleic acids and lipids. And if you put all those together, you get life, which is a property that those things by themselves don't have. Think about a chocolate chip cookie. If you take, you know, flour and sugar and eggs and chocolate chips, you'd all eat all those things without even, you don't have to put them all together, although they're better when you mix them all together. Flour by itself, yeah, that's not so tasty. But if you put them all together, you stir up all those ingredients and then you bake them in the match, or don't even bother baking them. The magic of chocolate chip cookie dough, that's an emergent property because the flour by itself really didn't taste like a chocolate chip cookie, but when you put them all together, you get something amazing beyond. Consciousness is an emergent property of like brain and human organism, which let's not go to the world of consciousness because I am a biology person, not a philosopher. When I was walking down the hallway on campus the other day, and a philosophy student came up and asked me, is it possible, I shouldn't even tell you this story because I can't even remember exactly how she phrased it, but actually, do you know everything in your brain, like you know all the knowledge in the world, and then a teacher or a course or something like unlocks the knowledge that's already in there, or do you actually like learn new things and like build your brain from the outside end, or do you build your brain, like your brain is already built and you just unlock the pieces, which has nothing to do with life. It's just saying the complexity of consciousness. There's actually philosophical questions that we could dive into. There's also philosophical questions about the properties of life that we could dive into. We're not going there. Instead, we are going to take a look at the five characteristics of life, and we're going to see where we're actually going to cover each of those characteristics throughout this entire course, knowing that life really is rather tricky and challenging to define. Are you ready to investigate the characteristics of life? Hierarchical organization first.