Speaker 1 00:00:05 ID the future, a podcast about evolution and intelligent design.
Speaker 2 00:00:12 Welcome to ID the Future. We've often been taught that hemology is one of the best evidences for evolution, but what does the data really show? Hello, I'm Eric Anderson, and today I'm joined by Dr. Stewart Burgess. Burgess is Professor of engineering design at Bristol University in the uk. He's currently editor of two bioengineering journals and a lead designer for the British Olympics cycling team for the Paris Olympics. He was lead designer for the European Space Agency working on the meta top satellites. He has had two research fellowships at Cambridge University and published over 200 papers on the science of design in engineering and nature. Welcome Stewart.
Speaker 3 00:00:49 Thank you.
Speaker 2 00:00:51 Well, Stewart, we are today here at the conference on engineering and living systems. It's great to be across the table from you instead of calling from overseas.
Speaker 3 00:01:00 Yeah, it's, it is, it is very good to be here.
Speaker 2 00:01:03 Yeah. We're glad you could travel and be here in Texas with us and join us for this wonderful conference. So, one of the icons of evolution, if you will, that we often hear about is the pen didactal limb. And that has been put forward for decades as one of the great evol evidences of evolution. And in terms of a homology, one of the great examples of how the human hand or the human foot is similar to the whale fin and therefore this proves evolution. In fact, I had just pulled up a few minutes ago, I just searched pen didactal limb in Google, and the very first hit said this is from biology online.com. It says a limb with five digits, such as a human hand or foot, which are found in many amphibia reptiles, birds and animals, which can allow us to deduce that all species derived from one common ancestor. Well, first of all, it's not a deduction, but, we'll, we'll set that aside. It would be an inference, but why did you get interested in the topic of the pen didactal limb and in particular the whale fin?
Speaker 3 00:02:01 Uh, well, I'd seen in the media that it attracts a lot of attention. And I mean, just to give one example, in 2021, there was quite a famous photo where a scientist in Denmark, uh, he got a beak well, and he actually dissected the flipper mm-hmm. <affirmative>. And he brought out this quite dramatic structure, which was like a, a hand in fact similar to the size of a human hand. And there were headlines ran the world saying, oh, this proves that, uh, wells have this leftover trait from their kind of land ancestry. But I could immediately see that there were very good design explanations to this. So, uh, I felt very motivated to explain to people that this, this icon of evolution, it was actually a very weak argument. Mm-hmm.
Speaker 2 00:02:45 <affirmative>. Yeah. So there's a number of things we could talk about in terms of the pen didactal limb argument. You can look at the, the sizes and the shapes and those types of things. But what I wanted to focus on today, because it really goes to your area of expertise, is the structural engineering side. And so let's talk a little bit about what it takes to build something like this. But first, let's analyze the evolutionary argument. Why, why is this an argument that they put forward and why do you think it's a weak argument?
Speaker 3 00:03:11 Well, they're saying that this pen, tactile limb, you have this common structure with, uh, fingers, often five digits and the wrist and the elbow joint and the shoulder joint. So they're saying, surely this means that, uh, one creature is an ancestor of another, but what they're not doing is looking to see if this is actually the best design. So all of these different applications, they're not considering that at all. And not only that, but they're, for example, not looking at the whale flipper and saying, well, it, it would actually be better if it was this design and not that design. They're not, they're not doing those things. They're not analyzing the requirements. So it's quite a superficial argument that the evolutionist is putting forward.
Speaker 2 00:03:52 Well, surely no designer worth his salt would make both the human hand append didactal structure and the whale fan append didactal structure. Right. I mean, that seems, that's kind of the argument that's laid out. That's the way it's popularized is surely no designer would do that because there's no good reason for that. And so it must be a result of some evolutionary history.
Speaker 3 00:04:13 Well, if you are a designer, you are always looking for the optimal design for that particular application. And when I look at the, the well flipper, um, I cannot think of a better design than a five digit, uh, hand like structure. Because if you look at the requirements, uh, a pectoral, uh, fin, the, the, the flipper, it has to very precisely move into different shapes. Mm-hmm. <affirmative>. So what mechanism are you going to produce to produce those finely tuned, uh, shapes? Because whales have to maneuver very precisely. If a killer whale is following, trying to chase mm-hmm. <affirmative>, a penguin or a seal, uh, penguins and seals are very agile. Right. They can change directions suddenly. So the killer whale needs to move its flippers extremely precisely. And you need some kind of hand structure to change the shape of that flipper.
Speaker 2 00:05:06 So what do you mean change the shape of the flipper? I mean, a lot of us might think if we're not familiar with this, that you just have a flipper, it sticks out there, you can move the flipper. Sure. But what do you mean by change the shape of the flipper?
Speaker 3 00:05:18 Well, the flipper is a hydrofoil, uh, it's basically a control surface. Mm-hmm. <affirmative>. So on an aircraft you have control surfaces, um, on other systems you have control surface. Even when you're swimming, you have to move your arms in very specific directions to change direction. And the well relies on its flipper to do that. And you need to change the shape, length ways, but also even in a cross section mm-hmm. <affirmative>, uh, in order to get these fine precise movements to change the trajectory of the well.
Speaker 2 00:05:51 Okay. So just for our listeners, so we can understand a little bit, if I've got my hand and I hold it up with all the fingers together, you're saying that I could maybe cup the hand a little bit or, or bend some of the fingers in and have a different hydrodynamic shape if I do that?
Speaker 3 00:06:05 Yeah. Um, cupping is a good example, but also twisting, sometimes you need to twist the whole of the pectoral fin. You've gotta remember that, uh, the whale doesn't have many control surfaces. It can, it powers through its tail. Mm-hmm. <affirmative>, apart from that, it cannot change direction. And a whale is so heavy it would find it so hard to to, to change its movement. So these flippers are very, uh, a very essential part of the well, and they have to move very precisely.
Speaker 2 00:06:32 How large can these get? In some whales, if we're talking about a flipper,
Speaker 3 00:06:36 Uh, for the humpback whale, it can go up to 15 feet in length. Okay. Uh, and some of the forces on it can be over one ton. So we're talking of very big structures, uh, and very strong structures. And again, there, there's an important point here that in order to withstand a load of over a ton, you need very strong structures inside that flipper. And a bone with, uh, tendons and muscles is exactly the kind of solution that you need. Whereas a little fish might have tiny ribs in in their, in their fins. That's not any good as a design solution for a well, it needs these super strong structures.
Speaker 2 00:07:17 Right. Okay. So we've got some massive forces being applied to these fins, uh, in these larger whales. And wouldn't it be better if somebody might ask to just have one big strong bone that goes out all the way to the end so that you've got this huge, uh, strong structure that can support all this weight?
Speaker 3 00:07:35 Well, that certainly would be very strong, but the problem is you couldn't then get a nice curvature in that flipper. If you look at some beautiful pictures of, um, humpback whales, you notice how the flippers have a very smooth curvature when they, when they bend. You can only do that if you have multiple bones. And that's needed for hydrodynamic, uh, efficiency. And not only this, but uh, research papers are being carried out dissecting, uh, various well flippers to look at their musculature, their muscles and tendons. And to the surprise of some researchers, they found that well flippers are full of flexor muscles and extender muscles, the kind of muscles we have in our fingers that obviously being fully functionally used in these Okay. Uh, flippers. So the evidence is showing that flippers do need all of these finger muscles and movements.
Speaker 2 00:08:28 Okay. And this is a really important point kind of on the side of what we're talking about, but back to the icon, one of the arguments is, well, we've got some stuff that's vestigial. Is the term used or it's leftover? Maybe it's not really performing in important function cuz gee, you just got the fin out there. Why do you need five? We'll call 'em fingers. They're not fingers cause they're not human fingers doing what we do with our fingers, but we'll call 'em fingers for purposes of the discussion here. You've got five fingers out there in this flipper. They must just be left over detritus from the, uh, evolutionary history.
Speaker 3 00:08:58 Yeah. That, that's just not true because those five fingers are absolutely fully functional as shown mm-hmm. <affirmative> by the research finding that, that they're fully functional because you need to change the shape of that flipper and you need multiple digits to do that. And even applying some engineering analysis, you could argue that five digits is actually an optimal number because on the one hand, five digits gives you enough to make a smooth curvature in the, in the flipper. But not only that, it's a low enough number to give you strength in the bones. Cuz if you have too many little bones, the bones are not very strong, uh, because the stiffness of a bone is proportional to the cube of its depth. So that means it's better to have a small number of big diameter bones than a large number of small diameter bones. And so it turns out that five is actually an optimal, uh, number from both a stiffness and a curvature point of view.
Speaker 2 00:09:54 Okay. Let's dive into that just a little bit because, uh, wa I know you stated it, but walk us through again, just so we can understand. So if we have one large massive structure, it's gonna be very strong, but it's gonna lack flexibility, is that what you're saying? Yeah. And, and ability to make some of these fine movements. If we have a whole bunch, let's say 10 or 20 fingers instead of five, you've got lots of ability to make movements, but you gave us some math just a second ago. Talk us through that. Why would that not have the strength that you need for this tonnage that the, uh, whale is supporting through this?
Speaker 3 00:10:28 Yeah. Maybe to give you an example from an aircraft wing, uh, which is itself a controlled kinda surface mm-hmm. <affirmative>, it's recommended that you have these deep section ribs to stiffen up, uh, the wing, uh, because you get a lot of stiffness through having a very deep section. So if you've just got a certain amount of bone material, rather than using that to have lots of little bones mm-hmm. <affirmative>, you're better off having, uh, at least a few bones with a big diameter, which gives you that depth, which gives you that big stiffness as we often see in engineering, in, in all kinds of, uh, structures. And as I say, it so happens that five gives you this trade-off number. Engineering is full of trade-offs. Right. Uh, you, you are rarely just maximizing or minimizing something. You are getting the best compromise between two extremes. Mm-hmm. <affirmative>, and you know, whichever way you look at it, five is a good compromise from a stiffness point of view and a shape point of
Speaker 2 00:11:29 View. Okay. So if I'm trying to build a foundation of a building and I wanna sync up pier, I'm probably gonna use one big, uh, thick pier for that particular corner. If I'm trying to build, I don't know, something that's much more loose that's gonna flutter around like a, like a, a wing or something like that, it might be less, but in this case where we've got, but even the wings, a pedical actually <laugh>, you know, that would be another example of some movement there. But in this case you're saying that there's some optimality. So the story is that we had this leftover and that's based on this idea of homology and we see that there's similarities, but you're arguing that the similarities are due to a purposeful design. Right?
Speaker 3 00:12:08 Yeah. In engineering, it's well known that a common designer gives common design. So you could look at the design of the space shuttle and see bolted interfaces, nuts and bolts and bearings and other parts, and you'll see those very similar parts in a train, in a motorcar right. In a bicycle, it's very common to see common design. And going back to the bento ductile limb, you could compare a robot with a digging machine and a space robot arm mm-hmm. <affirmative> and find that they all have a shoulder, an elbow, and a wrist. Right. So this is a kind of a universal design. Engineers are tool to, if you, if you have an arm system, then you always have a shoulder, an elbow, a wrist. So for an engineer, it's very natural to see this, this universal design appearing in different parts of biology.
Speaker 2 00:12:59 Right. The other thing that I thought was interesting that you had mentioned, uh, earlier was this idea of the structure of the arm. And you see this both in the human arm and the whale limb, although there are some important differences we could talk about in a minute. And that is that you begin with one large strong bone and then that as you go toward the extremity, that turns into two smaller bones and then three smaller bones. And talk us through that a little bit.
Speaker 3 00:13:24 Yeah. So this is another design feature of the tactile limb, which, which is really an optimal, uh, feature for, for two reasons. With most limbs, you want to twist them in the case of the human arm, if you have a screwdriver, you turn the whole arm. In the case of a well flipper, they also want to twist that mm-hmm. <affirmative> flipper, when you're twisting, you want to gradually do the twist through multiple joints through gradually increasing the number of bones. So it's optimal for twisting, but also if you are transmitting compression loads, uh, it's always better to do that going through one bone, then two, then three, then four. Uh, you are reducing your sheer dresses and reducing the chances of buckling. So from a structural point of view, that's exactly what you would expect to see. So again, that will be a reason for this common layout, the humerus bone, the, the radius bone, the wrist, and then the five digits.
Speaker 2 00:14:24 Ok. So sounds like it's a pretty optimal design choice, uh, in terms of the pen didactal limb for what the whale needs as well as for what we need. Is there, is there any other aspects of optimality that you wanted to bring out or I
Speaker 3 00:14:36 Think that covers it, but just to make the point that, uh, if it was true that the whale had this leftover relic of design, it would be easy to propose a better design. Mm-hmm. <affirmative>, but I've not heard anyone propose what would be a, what would be a better design for the whale flipper.
Speaker 2 00:14:53 Okay. So the evolutionists have commonly said, Hey, no engineer worth their salt would do this. It doesn't make sense in the whale. There's a better design. But you haven't heard any <laugh>?
Speaker 3 00:15:02 No, I'm still waiting.
Speaker 2 00:15:04 Yeah. That seems to be part for the course. I wanted to ask you one more thing about the whales. The other aspect of the whale, uh, physiology that's often put forward as a vestigial organ. Maybe not so much a homologous, but well, I guess partly homologous, but certainly as a vestigial organ that's useless is the pal pelvic bone structure. Yeah. Uh, tell us about that a little bit.
Speaker 3 00:15:25 Uh, uh, yeah, there have been some claims that you can see relics of, uh, leg bones coming outta the side of Okay.
Speaker 2 00:15:32 Yeah. Of,
Speaker 3 00:15:32 Uh, yeah, Wales. But in 2014 in the Harvard Gazette researchers admitted that they now realize they're not vestal at all these bones in inside the Wales near where the pelvis would be. They actually, uh, help support organs in, in fact, the reproductive organs of wells where everything is large in a, in a, in a well. Um, so they realized they, they're fully functional, they're not vestal at all. So that came out in 2014, but sadly since then, there are a lot of biology books. They haven't corrected that. Right. And they still wrongly stating these as, as best of your
Speaker 2 00:16:07 Parts. Yeah. Okay. So relatively recent data, but it certainly shows that when you don't know what something is doing, it's a bad idea to assume it's not doing anything.
Speaker 3 00:16:15 Exactly.
Speaker 2 00:16:16 Mm-hmm. <affirmative>. So another concept that you talked about is this idea that you proposed of extreme homology. What do you mean by that?
Speaker 3 00:16:23 Uh, so what I mean by that is some rather extreme cases where things are so similar, you could only really explain it by planning. So one of my favorite examples are marsupial uh, rats and placental rats. Uh, so in Australia you can find a marsupial rat and it looks from the outside remarkably similar to placental rats mm-hmm. <affirmative> that you get in America or Europe. And the analogy I would give would be two, say BMW motorcars. One is an EV car, the other is an IC engine car, but on the outside they look almost identical. Now that requires planning an engineer plan, the fact that you had identical body showers, but inside was completely different.
Speaker 2 00:17:08 We've got a car that's selling well, people like the look of it, they like the feel of it. We wanna keep that the same, but we're gonna completely swap out the engine. Uh, probably make changes in the drivetrain, probably a hundred other things. There are a thousand other things that you have to do to make that happen, but it looks like the same car basically until you look at the tag on the back and realize, oh, it's an ev
Speaker 3 00:17:28 Because it had very good aesthetics. Mm-hmm. <affirmative>, it was selling for good aesthetics. Right. The intelligent designer creates this beautiful, uh, placental rat mm-hmm. <affirmative>, and then thinks, well, let's have the identical body shell, uh, and make it up a marsupial one. Right. For a bit of fun, for good aesthetics. And I think that's very hard to explain by evolution, because if things change so much on the inside, how could the outside just so very similar. Right. So, so that's what I would call extreme homology.
Speaker 2 00:17:57 Okay. Interesting. Is there anything in the molecular realm that's similar to that? You're talking about organisms at this level, but
Speaker 3 00:18:03 Yeah. Well, I've done some literature surveys and, uh, was so fascinating to find that this, these similar structures are found in molecular biology and proteins, for example, you can find, uh, very similar protein structures in very different situations in different creatures. And even within one creature, the same protein structure, um, acts as part of the, for example, in a bird one protein that, uh, does something in the lens of the bird is also doing something in, uh, some digestive cycle. Right. Uh, so it's, and I think some of the researchers have been astonished to find some of these, uh, similarities. But as I was saying before, this is what you'd expect from a common designer reusing solutions in different applications. Mm-hmm.
Speaker 2 00:18:53 <affirmative>. Yeah. I think one of the researchers used the word moonlighting. We think this yes. This protein that we thought was doing X, we now I found out it's doing y So they said it's moonlighting as y, but it's
Speaker 3 00:19:02 Got a day job and then
Speaker 2 00:19:04 That job. Right. Exactly. But it's, but it's a, uh, a structure that is valuable and can be reused for a different application. Yeah. In the same organism even. Okay. Interesting. Well, anything else that you wanna share with us? Um, with respect to this idea of homology? Do you think the idea of homology is, is something that points toward design generally, or points toward evolution generally? I mean, do you have a feel for, for where that argument is going as we get more data coming in?
Speaker 3 00:19:31 I think it's a really fruitful area of research. Okay. And especially as engineers and our collaborating more with biologists, I think this is an ideal area to come out because in the past, biologists, biologists not knowing engineering, uh, maybe didn't know how to tackle this whole area of biology mm-hmm. <affirmative>, but now engineers are so often getting involved. I think it's a really good area for, for researching.
Speaker 2 00:19:55 Yeah. Well that's a very interesting approach because I think even for folks who've been skeptical of evolution or in the design, uh, movement, we often hear homology and we think, okay, uh, we don't agree with the storyline or the narrative that's been attached to that and that homology is something that we kind of need to defend against or attack. And what you're saying is yeah, that's fair enough in terms of the evolutionary story, but there's actually good reasons for similar structures in different types of situations, different types of systems. And so we can kind of take that on the, on the offensive if you will, and say, look, there's reasons why a design would make sense in this case, and maybe we need to revisit some of the, these homologies that have been classic, you know, icons of evolution to use Jonathan Well's term and see if there are good design reasons for these. And maybe it even becomes, uh, then a, an icon of design rather than an icon of evolution.
Speaker 3 00:20:46 No, that's exactly right. We need to articulate it and we need to get design experts in particular fields to articulate why that is actually the best design for that application.
Speaker 2 00:20:56 Excellent. Well, Stuart, thank you so much for being with us today. We're really, uh, glad you were able to fly all the way over here and participate in the conference. We really appreciated your contributions and the talks that you shared. So thanks for being with us.
Speaker 3 00:21:07 Thanks. It's great to be here.
Speaker 2 00:21:09 Thank you for joining us for this episode of ID The Future, to hear more about the important work carried out by scientists that shows evidence for design in nature and helps us better understand our own origins. Join us again here at ID the Future, or on our sister YouTube channel, discovery Science for ID the Future. I'm Merri Anderson. Thanks for listening.
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