Chris Kempes
speaker
209 appearances
1 recordings
1 series
first heard Jan 2025
last heard Jan 2025
Chris Kempes’s voice in public audio — every appearance, attributed to the second.
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And what's interesting is that pushes single-cell organisms to get bigger, and it pushes these spherical multicellular organisms to get smaller. Wait a minute. You've got to explain that. Yeah. So what's happening is the metabolic rate is decreasing.
And so it allows these single cell organisms to live the same lifestyle as sort of a larger size because they sort of don't have as much metabolic demand because everything is slower. And then these spherical organisms, as temperature decreases, they're facing increased viscosity, right? And so their life is a little harder for hunting. And so that's sort of pushing them to be smaller.
But then as the nutrients plummet, as the sort of total biomass starts going down, this pushes the multicellular organisms to get bigger and the single cell organisms to get smaller. And that's mostly a hunting effect of sort of gathering resources effect for the large spherical things. And so we think... this snowball pushes your multicellular organisms to get much bigger.
And as you start to get much bigger, you start to run into other physical constraints that would induce sort of more complicated geometries. And as you start to develop these complicated geometries, you start to discover things like sponges, we think. And then you find this multicellular architecture that's really stable and really beneficial. And when the world thaws out, you keep it.
You keep these multicellulars around.
Exactly. Yes, absolutely. Yeah.
Exactly. I think that's a new innovation. And you can imagine in a simple way why differentiation, what the calculus is of whether that's beneficial. So imagine I'm a sponge and I say, well... I have some reproductive cells and they, they sort of do the, you know, the reproductive bit of, of me and I have to grow and then I need things to feed that growth. Okay.
So now imagine I'm building a bigger, bigger internal sponge volume. And I just asked the question, if I add
a little differentiated cell that has cilia on the outside that drives fluid flow through the inside of me through these filters where I can capture prey and then eventually digest them do I get a return on investment for that you know every time I add one of these little cells with these little cilia which are just hairs that that move water um Is it beneficial to my total metabolism?
And so that's a case where, you know, maybe I have a few of those, maybe we're all that cell type. And then I say, okay, I make one of us reproductive and I keep all the other as sort of these gathering cells. Yeah. Now the reproductive cell doesn't have to keep around all these cilia, which it's not using, that's expensive. So I've differentiated to this one feature.
And now all of these ciliated cells don't need to try and reproduce. So I don't need to think about the downstream consequences of what molecules they have to carry around to be able to reproduce. I get efficiencies out of both of that, right? And that's sort of what differentiation is doing.
And I think that basic idea that when you take one thing that does everything and you split it up into subtasks that each do part of the thing but don't have to pay the cost of doing the other thing but still get the benefit from it, I think that's an idea that runs through economics, through biology.
It really is just sort of how economies of scale happen is through specialization and differentiation. And so I think that that idea is as true for a city as it is for a little sponge. And it's just about when you specialize, you don't pay you don't do all the things that you're not specializing in. So you don't pay the cost of trying to. Right.
And so, you know, I'm not currently paying the cost of trying to become a really good guitar player. which I know is not accessible to me. And so I happily consume really wonderful music from other people. And I get the benefit of that without needing to try to do it myself.
Yeah, I agree. I think development is astonishing, right? That you start off with one cell type and it divides and changes internal composition in terms of what proteins it has and what genes are turned on. And you go down this whole developmental cascade. There are ways to replicate where you don't do that, where you say, I'm actually just going to...
cut off a whole portion of the body that has all the different cell types already differentiated. And then all of those will replicate and rearrange and form a new functional differentiated body. There are a small number of organisms in different categories. I mean, small number of large multicellular organisms in different categories are able to do that.
Plants, to some extent, can, you know, sort of amazing, you can grow the whole plant back from enough of the right tissue excised from an adult plant. And planaria, you know, have all these strange things about them. how much they can replicate from bits. We had Michael Levin on the podcast talking about that stuff. Okay, great. Yeah, perfect.
There certainly are cases where you can do that, but it's interesting that it's not the norm for certain classes of complex multicellular organisms.
I mean, mammals are a relatively narrow taxonomic group, but we don't have any mammals that are just fully cutting themselves in half, and then every cell replicates and builds a second portion of its same tissue, and you get a whole new mammal that way. Right. Yeah, okay. No, plants are a large part of the world, and they're plenary everywhere, so it's a little bit of how you count it, but yeah.
Yes, absolutely. And I think that's actually the classic work that sort of re-kickstarted, re-kickstarted, that's a double rebooting, this sort of whole field and way of thinking. So those optimizations for the fractal geometry of vascular systems in mammals and plants are
Showing 161–180 of 209 · page 9 of 11
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