 So what is life? Well, this is a question that has received a great deal of attention. In fact, I have four humans up on the screen here who have written books basically titled What is life? The purpose of their books was to explore life and attempt to define it. My favorite one by far is Haldane in 1947 saying In his book entitled What is life? I'm not going to answer this question. I love that because dude it's a really hard question to answer and I think a big part of it is that we think it's easy It should be easy to define what is alive. In fact my oldest son took AP bio I think last year and we ended up in this like giant debate about Whether or not viruses are alive. I look forward to engaging in that debate with you all as well But when you look at like what some things we have an intuitive sense That they are alive like the crocodile if you came upon a crocodile You would know it was alive. You might not know If the crocodile were just chilling in the water like a log, you might not know he's alive But the second he makes this face at you, you're gonna know that he is alive You know here we have a like I love this picture. I think this bird is really beautiful Definitely we have a sense that yeah, this is alive this Elephant team like there's life here and we we look at it and we have Some affection or some we identify with these living creatures some living creatures we really identify with the whole primate crew like these are almost like family and we will talk about how that is Really close to being true, but the more similar critters are to us the more likely we are to feel like kinship and affection and cuteness, but you know what my my youngest son is a big fan of Insects and ants and raises cockroaches and cool things in his room We beg him not to let them out to Be in our house, but you know, we don't really identify as much like This may be a bit more of a stretch like what are the similarities that we have in common with like a butterfly But we'll learn in this class that we actually have a lot in common We also have a sense of things that aren't alive even though like I look at this waterfall this river and There's movement and there's change over time like there's definitely Activity happening with the water with the river itself with the waterfall But we have an intuitive sense that yeah, that's that's not alive even though it's doing some of the things that living things do Here's another picture of a waterfall. There's less life around this one That other that previous picture had tons of living critters green living critters around it But you know, you still would look at this and go. Yeah, that's not alive even though it's moving a desert Sands not alive. Like it's it's moving and it's changing It's dynamic, but it doesn't have the qualities of life, but Look at something like this like I actually have to refer what what is this thing? It's a crystal and crystals grow and they're minerals that change and and kind of expand and I look at this I'm like, oh my gosh, it looks kind of like a lichen. It becomes sort of Not easy not intuitive to decide it's beautiful and changing But for whatever reason and we're gonna look at those things it isn't classified as living this guy Mushrooms funguses are alive. I would argue that in that previous picture, you know, I I mentioned that it kind of looks like a lichen We'll just go back to it. This looks lichen-ish a lichen is a type of fungus and so You have to be careful when you like why is a lichen alive, but that beautiful ice crystal is not alive and How do we know that something is like what there's got to be some Characteristics that we can look at that are gonna tell us whether or not something is alive Some things we might be like dude. No, please. No, that is not alive or this is definitely not alive No, cannot possibly be alive when in fact all of those things are Absolutely alive. This is a shelf fungus that you know, what does it do? How does it change? How do we know that that is a living thing? I show you all of these only to say that it makes sense that there is Conversation that there is discussion that there is Debate about what makes something alive enough so that there are current interesting books and conversations happening about this topic We are going to attempt to get there We are going to attempt to get some definitions and the first thing we're gonna do is look at a quality of all matter but Something that's gonna help us define What life is and that's the hierarchical Organization of structures in all matter, but especially in living things