Skip to content Skip to sidebar Skip to footer

Widget HTML #1

Defining Life - Science With Tom #1

 Did you know that 30 percent of humans are walking around with a deadly bacteria living on their skin? Living things all around you. No. I mean literally. all around you - on your hair, in your nose, in your armpits. every surface you touch ever. Most are neutral or good but a few baddies like Staphylococcus aureus can wreak havoc in your body... but only if they can make a past your skin. Thank goodness for Lauren Popov. Before I could ask her about bacteria, we started with what I thought...


Should have been an easy question. TOM: What is the definition of life? LAUREN: That's your easy question? Tom - that's not an easy question. Sounds straightforward. Let's go to the dictionary. What do we need to do? So some biologists define a living thing as having certain traits. I guess is one way of thinking about it. So like a laundry list? Yeah, so think of a rock And think of your beloved cat, Stretch. I'm sorry to bring up Stretch. (TOM: I miss that cat). TOM: And I'm sorry you brought him up too. It's a little emotional LAUREN: OK don't think about Stretch. Think of a squirrel. Squirrels grow from baby squirrels to bigger squirrels. (Sure). Rocks don't necessarily do that. Ahh, I've heard of something called accretion - where rocks can be a bigger over time Okay.


Squirrels move. ooooh, that's true. but rocks also move over time - geological time that's true. Squirrels take in energy and metabolize it and excrete waste. I don't think rocks really do that. But I think that this demonstrates the whole problem with the trait definition of life. is that certain non-living things appear to have some of these traits. TOM:That's true. Like fire. Fire grows. Living things reproduce. You could say fire reproduces. Fire's not alive. Okay but that's another problem with these traits, is that I'm a living thing. I'm sure of that. I'm pretty sure you're a living thing too. And I have never reproduced. Are you sure about that? I am pretty sure. Yes, I'm pretty sure.


So how does this work? There's this list of traits, but I don't have all of the traits? Well, there's another way of thinking about what's alive. actually it's one of my favorite stories. It all started with a Dutch man - one of my heroes. Antonie Van Leewenhoek. He was a regular guy. He was a grocer. He was a janitor, actually. In City Hall. He had a srange hobby where he was really into grinding glass. He made the best lenses in the world. He was seeing things that noone in the history of the world had ever seen before.


And he started to look at things from everyday life under these lenses he was making. Like stuff from his grocer store. And actually even scraping his teeth - his nasty teeth - cuz back then they didn't brush their teeth ever. So it was really gross. TOM: brushed my teeth right before this interview. I'm glad because we're standing kind of close to each other.


He called them "animacules." TOM: Animalcules? LAUREN: Like, tiny animals. He called them "wretched little beasties." He's one of the fathers of microbiology And this guy was the first guy, in the history of humanity, to know that there were little microscopic living things? And he was a janitor in city hall. And a grocer! He worked really hard. Isn't that crazy! He sees these things and he's just amazed.


So what does he do? He starts writing letters to the greenest scientific minds in the world. He starts sending these letters to the Royal Society in London. TOM: That's how Robert Hooke found out about it! Yeah! And Robert Hooke, if you've seen "Cosmos" lately, with Neil De-Grasse Tyson. LAUREN: Oh, love it. Great show. They had Robert Hooke in a different historical anecdote and he was like this Disney villain They never showed his face and he looked like a little witch. He was the bad guy, but but he also had to do with some cells, right? So Robert Hooke, he looked at cork. It reminded him of monk's cells. TOM: Monk's cells? LAUREN: Yeah like jail cells TOM: cells that they lived in. LAUREN: Yeah, and he coined the term cell. But what I'm trying to tell you is that the cell is the basic unit of life. And so there are living things in the world that are multicellular collections of cells. TOM: Boom! You're looking at one. Cells make tissues. You'll get into that.


Yeah. We sure will. But there are also living things that are just one cell. Like what? Like bacteria. What's your favorite bacteria? Staphylococcus aureus. Do I have any Staphylococcus aureus on me? It is highly likely. We here in the science teaching establishment - I don't know about you scientists - We believe in evidence. LAUREN: I believe in evidence too. That's great. TOM: So prove it to me that I am made of cells and that I have a bunch of little unicellular things living on me. Let's do an investigation! Investigations are a critical part of science. To make a claim you need data. And to get data, you need to investigate. So our first investigation was a cheek swab inside of my mouth to see if I was made of cells. Then we looked at whether there was that nasty Staphylococcus aureus living in my nose picking region. So Tom, these are your cells. That's the nucleus right there. Four cells? Yeah several cells probably.


And do you see these little guys floating around? That's the size of the bacteria compared to a human cell. I have to admit This is some pretty impressive evidence that I am, in fact, made of cells AND that there's a bunch of little unicellular creatures living inside me. Ok, so we don't have time to look at the stuff that's growing in my nose. LAUREN: it will take a little while to grow. But I'm curious about staph. We have here some Staph aureus which we've engineered to glow green so that we can see it in our experiments. These are the very images we're going to show mark, and see what he says. Oh I can't wait to see what Mark says.


Mark, what's up man? It's good to see you. Let me show you an image right here. Now what does this look like to you? MARK: Blue dots. Like little puddles of water. And a mountain. Maybe trying to make the mountain grow? Right on, Mark. Thank you for sharing that. So this is Lauren's description of that same image. What you're looking at here is a picture I took on the microscope of a piece of human skin. The blue puddles of water are actually the nulcei of the skin cells. And the red are the boundaries of those cells. You can see the bacteria here as green dots. And the bacteria are actually growing and invading the skin. By infecting my skin culutures with bacteria that have different properties I can figure out what bacterial properties are important for them to be able to grow and invade and infect your skin.


Uhhh, whoa. First off, I tested negative for Staph. Yes! Second, I am so grateful to scientists like Lauren. The more we understand about the biology of how Staph survives and reproduces on our skin, The better we can design interventions to prevent those nasty infections. Before we get to the music video, I want to alert you to some supplementary videos we have for this episode.


There's "Science Vision", where Lauren explains her unique microbiologist perspective on the world. There's "Reading Framebow," where Lauren and I recommend a book about this history of microbiology. There's a bonus conversation about Lauren's previous love - viruses. And we've got a playlist featuring some of my favorite videos on the subject of defining life. Without further ado... shoutsout to Lou Reed, A Tribe Called Quest, and Danny Brown: "Is it Livin'?" As you noticed, there is not yet a "Verse Two" to Is it Livin'? It's up to you to write it. Yeah, kid! In the back of the class not paying attention. I mean you! Click on the music video link right there to see the full video and full instructions. Now as we grow Science With Tom on YouTube, it is super helpful to us if you subscribe to the channel If you comment with your questions for Lauren or me.


Name your cat "Science With Tom." Share this with your favorite science teacher or science student. And remember, with so much to think about, so many questions to ask, and so many resources available to us. If you stay bored in this world, you may be boring. See you next time..


Read More: What’s the Best Diet? Healthy Eating 101