[00:00:04] Speaker A: Id the future, a podcast about evolution and intelligent design.
Perhaps the most common evidence put forward to support evolutionary theory is the observation that organisms can adapt in particular circumstances or environmental conditions. We see them change, at least to a point. We're often treated to news stories and headlines about this or that organism evolving right before our eyes. Whether we're talking about classic icons of evolution like the peppered moths or the finch beaks, or new icons like E. Coli or guppies, we're told that even modest changes are evidence for the ongoing march of evolution. Hello, I'm Eric Anderson, and on this episode of Id the Future, I'm pleased to be joined by Doctor Emily Reeves. Reeves received a bachelor in chemistry with a minor in biology from northern Arizona University and a PhD in biochemistry and biophysics from Texas A and M. She currently collaborates on several research projects at the intersection of biology and engineering and is part of Discovery Institute's engineering research group. Alongside her research pursuits, she also serves as an active clinician specializing in nutritional genomics. Welcome, Emily.
[00:01:13] Speaker B: Hi, Eric. Thanks so much for having me on to talk. I'm excited to get into conversation with you today about adaptation and some icons of evolution.
[00:01:24] Speaker A: Absolutely. So, three years ago at our first conference on engineering and living systems, you'll probably remember I gave a presentation about adaptation and specifically argued that while we see many fascinating examples of adaptive change throughout the biosphere, there are limits to an organism's ability to adapt within a set of engineering operating parameters. And one of the examples I discussed was the work of David Resnick's team on Guppies, these beautiful little fishes that we all know from our childhood aquariums. So I'm super excited to have you on the show today because I know you've done a lot of additional work looking into these guppy experiments beyond what I did a few years ago. So I'm looking forward to learning a lot today.
[00:02:03] Speaker B: Sure. Yeah, I'm looking forward to talking about it.
[00:02:06] Speaker A: So before we dive into Guppy specifically, Emily, step back just a minute and set the stage. First of all, maybe tell us two things. Maybe tell us, first of all, why this concept of adaptation is so important within evolutionary theory. And second, if you'll pardon, I think it's fair to say that you came up through what I might call a standard biology and biochemistry training up through your PhD. And so, as an active member of our engineering research group, how has your view personally changed over the last three or four years as you've started looking at living organisms as deeply designed and engineered systems?
[00:02:41] Speaker B: Yeah, let me first speak to how my view has kind of changed in recent years.
[00:02:47] Speaker A: Sure.
[00:02:48] Speaker B: Yeah. So I did go through kind of, like, the traditional route, and I would say one of my first exposures to thinking about organisms as more, like, deeply designed systems came from reading Yuri Alon's book, an introduction to systems biology. And after I read portions and stuff of that book and really started thinking about it, it sort of made me really rethink and a lot of what had happened in graduate school, and just, I started thinking, like, oh, wow, if organisms are actually designed, then we need to understand more math, we need to understand more engineering concepts in order to do better biology. Like, it really struck me that, like, as a microbiologist or biochemist, like, I had been sort of so handicapped by not having some of those tool sets and not understanding, like, design motifs that we know from engineering, like integral feedback or feedforward loops, or, like, I had no knowledge of those things. So they could have been right before my eyes when I was, you know, studying the bacterial system. And I wouldn't. I would never have, like, even known what it was or recognized it. So, yeah, so that's like, I guess, some of the things that happened that really helped me realize, like, how important it is for biologists to learn more engineering, to understand more of these design concepts, because I really believe it can help us be much better biologists and biochemists.
[00:04:24] Speaker A: Yeah, that's great. Appreciate you sharing that.
[00:04:26] Speaker B: Okay. And then to your second point, or, sorry, your first point. As a young scientist, you know, I heard these confident statements, like, today, the theory of evolution is in about as much doubt as the theory that the earth goes around the sun, you know, by Richard Dawkins.
[00:04:43] Speaker A: Right.
[00:04:43] Speaker B: And then in graduate school, I remember people saying, also repeating this, that nothing in science makes sense except in light of evolution by Theodosius Dostansky.
And these statements are designed, I think, to make people believe that the breadth of what the word evolution encompasses is a settled topic.
In my personal experience, in so many scientific circles, evolution without any nuance is just discussed as a fact.
And I think, of course, when the term evolution is used to mean adaptation, then it is a fact. Right. We all observe that bacteria adapt to the presence of an antibiotic and develop resistance. Nobody questions that. Yeah, but then there's a much smaller group of people that feel comfortable then extrapolating that into evidence that life emerged from non life. Prokaryotes turned into eukaryotes, and man came from monkeys.
[00:05:48] Speaker A: Yeah. And if you go back to, like, Dobzhansky's statement, which, first of all, is very self serving. But, you know, people kind of use that to almost equate biology with evolution, and that's a really dangerous mental mistake to make. If you think that. That everything in biology is evolution, then you're going to get off track pretty quickly.
[00:06:10] Speaker B: Yep. And part of that is because of, you know, there's lots of meanings of this word evolution and all of that, too.
[00:06:18] Speaker A: Yeah.
[00:06:18] Speaker B: So, yeah.
[00:06:20] Speaker A: So talk to us a little more about adaptation. There are some amazing examples of adaptation.
[00:06:24] Speaker B: Right, right. The degree of adaptation that we see is sometimes really mind bending. Right. But everybody agrees with it. And like I said before, adaptation is a fact. We see it all across life, and we observe it. But I want to make the point that adaptation doesn't constitute evidence that these entire organismal systems can or did emerge from an undirected process. These are separable things. And as an example of that, I want to say that engineers build adaptive systems all the time. And those adaptive systems that they build, they can more if and be flexible. And just because they morph in extreme ways or in ways that may even be hard to recognize that it's the same thing, that doesn't mean that those adaptive systems evolved. Right. They were human, engineered, designed from the top down.
And so as evidence for macroevolutionary changes, we keep being handed these examples of adaptation, but it's kind of flawed from the outset because designers can build adaptive systems, and it's especially flawed when the mechanisms of adaptation don't match up with the necessary mechanisms of darwinian evolution, which are random mutation and natural selection.
[00:07:42] Speaker A: Yeah, it reminds me, Philip Johnson used to say, I asked people for evidence of evolution. What is your evidence of all this creative power? And he says they would always come back with the finch beaks or the peppered moths or the bacteria and the antibiotics. So that's definitely still the case today, I think, in a lot of what we see. All right, so with that background, Emily, tell us about the example of adaptation you want to share with us today.
[00:08:06] Speaker B: Sure. So the example I want to talk about today is, as you mentioned already, the humble guppy, which is native to the steep mountain streams in Trinidad, which is an island off the northern coast of South America.
[00:08:20] Speaker A: Yeah. Awesome. So take us away. I'm picturing this beautiful mountain sea at the southeast, pointing to the west endings, just on the edge of the caribbean sea. Maybe we should go check it out. What did people observe in this location that they thought constituted evolution happening right before our eyes, as they said?
[00:08:38] Speaker B: So in these mountain streams, there are waterfalls that create these kind of natural barriers between different pools. And there was this man named Carl Haskins, and he documented that between upstream pools and downstream pools in these streams, the guppies that lived in these upstream and downstream pools had pretty strikingly different phenotypes. And so the guppies in the upstream pools where there was less predation, and we'll talk about that a little bit more in a minute, they were actually larger, bigger sized, and they had delayed time to sexual maturity, which means they could have hold, the females could have more eggs.
Now, the seemingly major difference between that upstream environment and that downstream environment is predatory fish. Upstream, there are fewer and different types of predators.
[00:09:32] Speaker A: And when was this?
[00:09:34] Speaker B: So the documentation of this, I believe, was in the 19, like fifties, sixties.
[00:09:41] Speaker A: Okay. Yeah. Because this got repeated a lot, I think, in one of the things that you wrote up. And by the way, we'll, we'll include some links to your write ups. So I think you mentioned in your write up that Miller had put this forward as a great example of evolution taking place. And of course, other researchers have as well.
[00:09:58] Speaker B: Yes, that's right. So, yeah, Kenneth Miller, he summarized these experiments in his book finding Darwin's God, and he described this as a kind of like an icon of evolution that we talked about where, you know, it's happening before our eyes. We see this very. We see a lot of evolutionary change in a short period of time kind of thing.
[00:10:22] Speaker A: Yeah.
[00:10:23] Speaker B: So the initial observation of differences between guppies and upstream and downstream environments by Haskins launched this series of beautiful experiments that were led by Professor David Resnick, who captured the guppies from the downstream pools and then moved them upstream. So he moved them from where predators were prevalent downstream to where the predators were rare.
And then what Resnec's team observed is that the guppies from the downstream pools underwent these rapid transformations when they were placed into that new upstream environment. And everyone assumed the rapid transformations from the guppies were due to this predator, direct predator based selection acting on random mutation. But then Resnick did some careful experiments over the past, like, 40 years. He's done like, 40 years of experiments, which shows that this actually turns out to be incorrect.
[00:11:17] Speaker A: Yeah. Now, when you say rapid transformation, what are we talking about? Because he's been working on this for several decades. But if I recall from one of the things I had read a few years ago, I mean, it was a matter of, what, a year or 18 months or something, they started noticing changes, or am I misremembering? That.
[00:11:34] Speaker B: Yeah. So when I'm using the term rapid transformation here, I'm using the term in the sense of what was expected based on, like, mutational, kind of like random mutational change. For instance, when the team calculated the rate of evolution, they initially used this unit called a Darwin, and they reported, you know, that the guppies. The guppies changed.
[00:12:00] Speaker A: I'm sorry, go ahead.
[00:12:02] Speaker B: Yeah, they reported, you know, that the guppies changed at this, you know, really, really fast rate.
[00:12:08] Speaker A: I remember a quote from one of the papers. This was, I don't know if it's the same paper you looked at, but the one I was doing for cells, they said something like, I won't pull it up right now, but they said something like, it happened a thousand times faster than we expected.
[00:12:22] Speaker B: Yeah, exactly. So they were calculating the rate of evolution based on a unit called the Darwin. And that is a unit that's really used in to calculate the rate of change in fossils. And so what they were saying is that the rate that the guppy is changing compared to the rate of change we see in fossils looks like it's really fast.
[00:12:45] Speaker A: Mm hmm.
[00:12:46] Speaker B: So it was in that. It was in that context. But we're not talking about like, oh, the guppy changed in like a day or two.
[00:12:52] Speaker A: No, no, no, no. But, but in a. Yeah, very rapidly compared with what we expected. Yeah. And of course, when they did this calculation and determined that the change was happening vastly faster than their evolutionary theory would have predicted, they decided maybe they should question evolutionary theory. Right.
Or did they say, oh, isn't evolution amazing? It happens faster than we thought.
All right, so how did they test this hypothesis?
[00:13:22] Speaker B: They realized that if the changes they were seeing in the guppies were due to predator based selection, that the smaller fish in the downstream pools should have a lower death rate.
But then they measured the death rates for both sizes of fish, juveniles and adults, and those rates turned out to be the same. So this means that the direct predator based selection was not responsible for the phenotypic changes.
[00:13:49] Speaker A: Yeah.
[00:13:50] Speaker B: And then Resnick's group gives a new name to what they were observing called density dependent selection.
And there's still kind of mystery around what is actually going on here, and we're going to talk about that in a few minutes.
But to directly quote from their 2019 review, they state, quote, we have shown that the agent of selection on the life history, behavior and physiology in low predation communities is high population density and the cascade of ecological effects that stems from it. Quote.
So they also moved downstream guppies.
So they moved the downstream guppies into upstream environments in three to four separate streams. So this sort of represents independent experiments. And for each of those independent experiments, they observed the same allele frequency shifts for all those experiments. So what this means is that the rapid transformations are not due to random mutation because. Right. What are the chances of you get the exact same random mutations in three to four separate times?
And other experiments they conducted also confirm this.
So the phenotypic differences come from standing genetic variation that exists in the population of the downstream guppies.
[00:15:09] Speaker A: Right. And do you remember from the papers when you say they moved from three to four downstream environments to upstream, is it within the same stream in four different streams? Or did they actually cross streams? Do you remember?
[00:15:21] Speaker B: It's different streams, I believe. Different streams.
[00:15:25] Speaker A: All right, so they are ruling out this traditional view that was there for a long time, that this was predator based selection.
[00:15:35] Speaker B: Yeah, direct predator based selection. Right.
[00:15:37] Speaker A: And they're coming up with something called density based selection. So they still think that natural selection is the driver here. Is that what's going on?
[00:15:44] Speaker B: That's right. Yeah. So these repeatable parallel changes, they're often considered an incredible display of natural selection.
[00:15:52] Speaker A: Of course.
[00:15:53] Speaker B: Yeah. Many scientists think that the standing genetic variation. Right, which is enabling these phenotypic changes ultimately rose from random mutation as well. Of course, the mechanism that's now maintaining that standing genetic variation. So you have a situation where random mutation and natural selection are being attributed as both the ultimate cause under either the direct or indirect hypotheses for how the predators were shaping the guppy evolution.
And my question is really, like, is this fair?
[00:16:30] Speaker A: Yeah, I think Gould might disagree. You know, the whole contingency idea, you know, if you see something that is happening rapidly, repeatedly, you're probably not talking about traditional evolutionary theory. So what else are they coming up with? What do they think this standing genetic variation is doing here?
[00:16:51] Speaker B: Reisnik's work shows that the standing genetic variation was already baked in within the downstream guppy population. And that leaves no room for random mutation now, because the variation was baked in, this places the novelty generation back into history, further back in history, into a setting where there's less direct access to the environmental pressures that the variation is responding to.
[00:17:22] Speaker A: Exactly.
[00:17:23] Speaker B: So what a lot of people, I think, were really curious about and these experiments were set out to answer how, why, and how fast does adaptive evolution happen in the real world? Well, we're kind of left in a place where that's not actually being answered because there's nothing being answered here about genetic novelty.
Yeah. So, thus, the guppy transfer experiments, they don't really provide favorable evidence for darwinian macroevolution. Instead, they demonstrate population dynamics, which is where preservation of genetic diversity amongst the population means that individuals within it represent different optimizations for unique environments. The essential question, you know, that most people are curious about what is the source of that, of the. Of the genetic novelty here. That question remains unanswered.
[00:18:21] Speaker A: Yeah, and that's super fascinating, Emily, because, you know, the traditional view says you've got sort of this population and everything's the same until there's some mutation that causes a difference, and then that may or may not get picked up by natural selection. I mean, even if you go back to, like, what, the finch beaks or the peppered moths, I mean, that's sort of the view that you have. And yet it appears that there's some variation within the population the whole time. And certainly in this case, that appears to be. To be the case. So how do you get a situation where the population has some variation within it and.
[00:19:00] Speaker B: And it's maintained and that. That.
[00:19:01] Speaker A: Yeah.
[00:19:02] Speaker B: You know, that that population is maintained. Right. That you don't. That you don't lose it? It's a very fascinating scientific question.
[00:19:10] Speaker A: Right, exactly. Because then what it allows the population to do is, of course, you know, life or death happens at an individual level, but it allows the population to rapidly respond to environmental challenges and keep going as a species. And one of the things that we don't need to talk about, we don't need to talk about might in detail. But one of the things that I had mentioned earlier that we talked about is the design parameters.
I like to view the parameters within which an organism can operate like a gravity well, if you will, where the organism tends to be at a particular stable location and get. Can get perturbed, but it tends to go back to the norm when the environmental condition has changed back from whatever the challenge was that it was experiencing at the time. And having this standing variation within the population seems to me to be a really interesting and valuable way to rapidly do that.
[00:20:04] Speaker B: Yeah, yeah, exactly. Yeah, that's. And, Eric, I think you've done some great thinking and how the gravity well model is a good kind of way of thinking about the adaptation. We see that when we see an organism adapting to something, it's not that that organism is actually evolving, but that instead that organism is actually adapting to stay the same.
[00:20:28] Speaker A: Exactly. Yeah. It's battling valiantly to remain a guppy. It's not in the process of turning into a goldfish or a whale or something else, which is the evolutionary story, right, over time.
[00:20:40] Speaker B: Right?
[00:20:40] Speaker A: Yeah, exactly. And that's what we see in all these cases. I mean, again, whether you go back to the peppered moss or the insects and the insect type insecticide or the bacteria and the antibiotics, even Lenski's experiments, every single one of these evolutionary icons, what we see is that the organism has the ability to temporarily adapt to environmental challenges while ultimately resisting fundamental change. These guys are still guppies, and there's no evidence that they're ever on their way to being anything other than guppies.
[00:21:10] Speaker B: Right. And this fits so well with the engineering model that would predict that guppies are designed with operational parameters for different traits, like. And some of those being, like, time to sexual maturation. Right? In the case of the guppy, size, color, et cetera. And those operational parameters are set by an overarching design logic.
[00:21:32] Speaker A: Right.
[00:21:32] Speaker B: One way to think about an operational parameter is as a variable, right. That's designed to change within predefined limits in a system. I don't know, Eric, if you have any examples of that that you like to share, you have maybe more background on that than me.
[00:21:50] Speaker A: I think that the ones that we do see are, like, even all the classical examples that I mentioned, that what we see in E. Coli or what we see in the peppered moss or the finch beaks, or even if you look at, you know, the plants that you put in your yard, if you give them, you know, different nutrients or different sun or different water, there's a lot of variation that happens. But in all the cases, they're responding to those challenges in a way that is within those parameters. As long as they stay within the parameters, they get to keep living. And once they drop outside of their variables, out of their parameters, then they die. And it's really pretty straightforward, actually, in that sense.
[00:22:30] Speaker B: Yeah. And another way to maybe think about this is engineers, when they design something, these variables, they want them to be able to change or be adjusted for optimality. So one example that I can kind of wrap my head around is, like, the angle maximum on the front wheels of your car.
The designers, they want that to be able to, like, maybe if it's a race car where you're going really fast, maybe you can't change it quite as much. But then maybe if you're, you know, using, like, an ATV or something, it can change more so that you can make a really tight turning radius or whatever, so.
[00:23:15] Speaker A: Right, exactly. Yeah.
[00:23:17] Speaker B: The variables can be changed depending on the design requirements.
[00:23:22] Speaker A: Yeah, I like that example. In fact, a few years ago, I bought an suv which had a higher wheelbase than my wife's car, and was annoyed by the fact that the turn radius was so much wider than hers. She could turn with a much wider radius. And they obviously didn't set the radius as tight for my car because they didn't want a higher. A car with a higher center of gravity tipping over.
[00:23:47] Speaker B: Yeah.
[00:23:48] Speaker A: At a high speed. So that's a great example. I like that.
[00:23:51] Speaker B: Yeah.
[00:23:51] Speaker A: So, all right, so let's talk about these guppies and what Resnick's doing and how some of these variables could be maybe tuned to. To produce adaptation in something like these guppies.
[00:24:03] Speaker B: Yeah. So there's a couple different models from the engineering perspective, that could tune variables. Right? Like, let's say, like when you're looking at the guppy, maybe the color of the guppy, the, you know, the age to sexual maturity. Let's think of those as variables. Right. And then let's think about what are some different mechanisms, design mechanisms, that might exist to tune those based on the environment the organism is living in. And so the model which currently has the most support and is favored by Rhiznec and other groups data involves what we have kind of already talked about, which is where there's genetic diversity in the population.
That means that certain individuals within a population represent different optimizations for a unique environment. And you can think of this as kind of like a normal distribution where individuals on one tail of the distribution are not well suited for, let's say, the downstream environment. But if you move them in the. Into the upstream environment, gradually their alleles become more dominant, because it's just they're optimized for that environment. So in this model, the population's architecture includes diversity, and the diversity is different. Optimizations for unique environmental situations.
[00:25:33] Speaker A: Right. And it could be relatively complex. I mean, if you had a situation where there's a bunch of variables, right, you could have a variable per ph, you could have one for temperature, you could have one for color, you could have one for something else. So there could be lots of these variables working together. We're not suggesting that it's as simple necessarily, as you only have one variable for this organism. But in some of these cases, I think Brian even had some examples where just a couple of tuning knobs, as he called them, two or three variables were able to make really significant phenotypic changes in the stickleback fish. So it'd be interesting to see what we find out with the guppies as more research happens.
[00:26:08] Speaker B: Yep. Yeah. And a second hypothesis for what's the mechanism that's tuning these variables is that there is a sensing mechanism.
And how that would work is that in response to, let's say, environmental inputs, that somehow triggers some kind of germline allele reprogramming. And so this would rely on an organism sensing changes in the environment and then some kind of triggering internal programming of allele frequency in the next generation. And I really want to emphasize here, this is a hypothesis. There's not a known mechanism for this that's been, like, worked out that I'm aware of, but there is, I think, quite a bit of evidence that something like this may be happening. So, for instance, like you mentioned before, cichlid fishes, stickleback fish, Drosophila Darwin's finches, all of these organisms have a similar pattern to the guppy of these repetitive, parallel changes in specific traits in independent experiments. And when you look genetically, they're actually having the same allele frequency shifts. Shifts. That's how we know it's not random mutation. Right. Because independent experiments are happening, and we're seeing the same allele, allele frequency changes. So we know it's not random mutation. But. And I found when I was, you know, reading about the guppies, and I found this one study that had, I think it was, like, from 2023. It's very recent. They actually reported that there were substantial differences in germline mutation rates among three separate guppy families. And I think that seeing that kind of finding is expected on a model where maybe certain individuals within the population are being programmed for adaptation via, like, some kind of directed change, while others are not. But there's a lot more research. Right. That's needed to. This is just a hypothesis and kind of my musing, but I think a couple questions that can really, we can think about that might help us answer this is, for instance, can we identify a sensing signaling mechanism that drives these changes in the guppies? Like, are there pheromones that the fish are sensing that detect their density? And when they realize, like, oh, there's more fish around, then they say, oh, well, we don't actually need to.
We can have a longer time to sexual maturity now.
And I think one way to do this might also be to transplant guppies that are lacking the alleles that are thought to be required for upstream change, and then observe, like, just transplant those guppies. Right. And see if the adaptations still happen. You know, if there's no directed change, no kind of programming like that happening. Then we shouldn't see those.
Those fish shouldn't be able to adapt.
[00:29:09] Speaker A: Yeah. So let me, let me dig into this a little bit. I don't, I don't know if you know this from the paper, but let me just ask the questions and we can chat a little bit. So when they took the guppies from the downstream pools and moved them upstream, were they testing them for any genetic particular traits at that point, or were they just taking organisms and moving them?
[00:29:30] Speaker B: I don't think that they have specifically only moved certain guppies with certain genetics.
[00:29:38] Speaker A: Okay.
[00:29:39] Speaker B: Yeah.
[00:29:40] Speaker A: And then are they tagging them? So they.
[00:29:42] Speaker B: I want to caveat that by saying there are 40 years of experiments here, over 100 papers.
[00:29:47] Speaker A: Fair enough. We're looking at a few very specific studies here. So that's a good caveat. So they're moving. I'm talking about Resnick's work that you've reviewed here. So they're moving some guppies from the downstream to the upstream. And are they tagging them so they know which ones are which are they then just coming back and looking at the overall population?
[00:30:06] Speaker B: Yeah. I'm also not 100% sure on that. Like, when they, when they measured the death rates in the guppies, they did have a way to mark them, that mark. They have a mark and recapture method. So they do have a weight ability to do that. But I'm not sure that they were. They did. They definitely don't do that all the time.
[00:30:29] Speaker A: And as far as we know, they weren't looking for specific genetic traits before the move. Okay. All right. But you've raised some questions that could be answered kind of under a design framework. You know, can we look for a sensing mechanism? Is there a signaling processing mechanism? Is there different things within the environment that could potentially be triggering this or act as environmental challenges that they're checking for? So there's a lot of research that could be done right under a design framework to try to continue to work on this.
[00:30:59] Speaker B: Yep, that's right. And Rhiznext group, they've done amazing work. I mean, 40 years of research on these populations, 100 papers, like, they've done really detailed, careful, careful studies on these fish.
[00:31:12] Speaker A: Well, let me ask one more question again. If you. If you don't recall from the papers, that's fine. But so when they move these up from the downstream to the upstream, there's. There's greater population density, is that what they're saying? Because there's fewer predators.
[00:31:28] Speaker B: Exactly. There's fewer predators. And so the population density of the guppies increases in the upstream environment.
[00:31:35] Speaker A: Sure. Okay, fair enough. Then why would population density cause slower maturation? Right? I mean, is there. Are they claiming that there's some lack of food, or are they claiming that there's something in the fact that there's. I mean, you understand what I'm saying? There's got to be a causal connection. And it seems like just saying, well, it's natural selection is not a causal connection.
[00:31:59] Speaker B: Yeah, I mean, when they have. So one benefit of having, like, slower time to sexual maturity is they actually, the females are able to carry more eggs.
[00:32:11] Speaker A: Oh, yeah, I get that. There's benefit in that aspect.
[00:32:16] Speaker B: Right.
[00:32:16] Speaker A: I'm saying, why would population density cause slower sexual maturation?
I mean. Yeah, there's no logical reason necessarily, why those are tied together, correct?
[00:32:28] Speaker B: Yes. Yeah. Yeah.
[00:32:30] Speaker A: Okay, interesting. All right. And you're not aware that they had addressed that?
[00:32:34] Speaker B: I haven't. I didn't read anything specific to that topic.
[00:32:38] Speaker A: Okay. Okay. All right. Well, let's, let's set that aside for a minute. Let's talk a little bit more about this, you know, design engineering model and how we could differentiate or the kinds of questions that we might be looking for as we look at adaptation. So again, typically, if we're talking about a design engineering model, we expect the adaptation is going to be regulated. It's going to be based on specific parameters, it might be reversible, and it's going to be probably a predictable feature, which is very different. All of those things are very different, at least from the traditional darwinian view that it's random, it's contingent, it takes a long time, it's probably not repeatable, Gould said. And so it's a very different approach there. And then the other thing that we focus on, and you and I have talked about this, of course, is that we're really looking at the organism as the agent of change here, not the environment. It's the organism that decides whether it's going to move in a particular direction or adapt in a particular way, rather than viewing the environment as exerting quote unquote, pressure on the organism. And it's that design of that organism that determines what stimuli the organism is able to track and respond to. If it doesn't have that ability to respond to a stimulus, it won't. Right?
[00:33:55] Speaker B: Yeah, yeah. Those are great points, Eric. I also would add that environments do not possess agent like capabilities of kind of like selecting which organisms will breed. So. Right. The environment isn't like a breeder in the sense of like, oh, I'm gonna get a dog that can chase sheep faster kind of thing.
The traits of the organisms themselves are actually seem to be responsible for the change. And then organisms are problem solving entities. They are not passive objects. Right. Just being shaped by the environment.
And then finally, these operational parameters that we see in organisms, they have a limited range. So I know we said this before, but organisms adapt to tolerate an environment, but they're adapting to stay the same. They're adapting not to die.
It's more of like the design model, I would say.
[00:34:54] Speaker A: Right, right. Okay. Well, this has been super fascinating. So just to kind of wrap up here a little bit and summarize what we've talked about with Resnick. Great work on this. So I guess what we're seeing is that he argues and agrees that what we're seeing is not attributable to random mutation, that piece of the traditional story.
Instead, what he's seeing is that there's rapid, repeatable, reproducible shifts that we can see in this situation when they move them from a lower, from one environment to another environment.
And he's arguing that the reason for this is because there's differences in the genes that are already in the population. And he calls this density dependent selection. But how does this also tie in to the general theory of evolution, in your view, Emily?
[00:35:44] Speaker B: Yeah. So I think that the results from these guppies experiments, it really poses problems for the grand evolutionary hypothesis, because here. Right. The guppies are an example of we're seeing rapid adaptation. This has been called an icon of evolution, and not only an icon of evolution, but it's been called like an icon of macro evolutionary change like these, you know, the kind of change that's necessary, supposedly, to take one organism to being a different organism.
But when we really, but when we really dive into the details, the mechanism of what's going on here, we realize that the source of genetic novelty in what's allowing these organisms to change is still completely unknown.
It's built in. What we see is that what's allowing these organisms to change so rapidly is built in, and it's reproducible. So it's not darwinian at all, where it's random mutation and natural selection. Random mutation has been eliminated as the cause for the rapid parallel changes in the guppies. And that's huge, right?
[00:36:54] Speaker A: Yeah.
[00:36:55] Speaker B: Darwinian evolution relies on random mutation as its driving mechanism. And then predatory driven selection, which is a form of natural selection, has also been eliminated as a possibility. So we're kind of left at this place where the question that really, you know, gets at the heart of what a lot of people think these kinds of experiments show really hasn't been answered. And that is, you know, where is the genetic novelty that's enabling this adaptation?
Where is it coming from? All we know from Rasnek's experiments is that it exists in the population.
We don't know where it came from.
[00:37:36] Speaker A: Right. That's, that's really great. I like how you summarize that, because here we are at the end of his 40 years of experiment and now 60 years after the initial observation, and we still don't really know exactly what's going on. But one thing we do know is it's not random mutation and it's not predatory driven selection. So those two proposals are now gone.
[00:37:59] Speaker B: Right.
[00:38:00] Speaker A: So now we're still left to say, okay, where did the novelty come from? And is it possible that there's some engineering based approach here either in sensing the environment or at the very least, in maintaining this genetic diversity within the population?
[00:38:14] Speaker B: Right, right. Yep.
[00:38:17] Speaker A: Awesome. Well, Emily, thank you so much for being here today. We're going to link to your two recent write ups at Evolution news for anyone who wants to dive a little bit deeper. But really appreciate you being with us today to help us understand more about this topic. This is such an important topic of adaptation. Really appreciate it.
[00:38:32] Speaker B: Yeah. Thank you so much, Eric. It's my pleasure.
[00:38:35] Speaker A: Thank you for listening to this episode of ID the Future. To learn more about the adaptive capabilities of living organisms and the remarkable design and engineering behind these systems, join us again at ID the future or on our YouTube channel Discovery science, and help us share these important messages by sharing a link with a friend. For id the future, I'm eric Anderson. Thanks for listening. Visit
[email protected] and intelligentdesign.org. this program is copyright Discovery Institute and recorded by its center for Science and Culture.
