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Whether you slither, swim, or fly, it's all the same
December 30, 2005 3:36 AM   Subscribe

"[E]ven though you couldn't predict exactly what animals would look like if you started evolution over on earth, or it happened on another planet -- with a given gravity and density of their tissues, the same basic patterns of their design would evolve again." A new study models all forms of locomotion -- swimming, walking, flying by muscle or flying by 747 -- in one physics theory, and stultifies Stephen Jay Gould's conjectures about the "contingency" of evolution. [mi]
posted by orthogonality (62 comments total)

 
In America, Stephen Jay Gould was regarded as perhaps the most famous proponent of evolution. Biologists held him in less esteem: as John Maynard Smith explained
"Because of the excellence of his essays, he has come to be seen by non-biologists as the preeminent evolutionary theorist. In contrast, the evolutionary biologists with whom I have discussed his work tend to see him as a man whose ideas are so confused as to be hardly worth bothering with, but as one who should not be publicly criticized because he is at least on our side against the creationists."
One of Gould's strongly held beliefs -- a belief unsupported by any real evidence -- was in the contingency of evolution: he wrote "...history includes too much contingency, or shaping of present results by long chains of unpredictable antecedent states, rather than immediate determination by timeless laws of nature."

The new study undermines Gould: at least when it comes to movement, a single "timeless law" of physics models all forms of animal locomotion, even locomotion via airplane: "We found that all of the motors used by humans and animals for transportation have a common upper limit of mass-specific net force output that is independent of materials and mechanisms."

"From simple physics, based only on gravity, density and mass, you can explain within an order of magnitude many features of flying, swimming and running,... It doesn't matter whether the animal has eight legs, four legs, two, even if it swims with no legs."
posted by orthogonality at 3:37 AM on December 30, 2005 [1 favorite]


(How does this model get verified empirically?)
posted by Rothko at 3:44 AM on December 30, 2005


(We build-or-go-find Earth#2, with an identical gravity to Earth, terraform it, and then seed it with the basic primordial elements of life, and, then wait a couple million years -or- pray for ID to kick in? :)
posted by yeoz at 3:55 AM on December 30, 2005


Why is Gould getting dragged into this? He's mentioned once in the article, right at the end, in a single suspiciously general-sounding sentence.
posted by Ritchie at 4:05 AM on December 30, 2005


Biologists held [Gould] in less esteem

that's really not true. Gould's big book is held in very high regard by a number of evolutionary biologists I know (mainly working in evo-devo). Sure, Gould had his faults but evolutionary theory is a very quarrelsome field at the best of times.
posted by tnai at 4:06 AM on December 30, 2005


I'm not clear on what one view has to do with the other. The "timeless laws of nature" must be understood as the context of contingency -- gravity, the chemical properties of carbon, all of these are basic physical facts that haven't changed. (At least as far as we can tell.) Nothing at all makes sense if you don't do that, so we can assume that Gould did that, also.
posted by lodurr at 4:21 AM on December 30, 2005


Gould also led the lynching of EO Wilson. For that, Gould deserves whatever kicking around we can give him.

Actually, I thought of Gould's contingency before I read to the end of the article (really, I did!), and saw that Marden mentioned him. Gould's contingency was only one of his many overreachings, and I thought that controversy gives a "big picture" that this theory fits into. The theory is very interesting by itself, but even richer when it's put into context. And I always enjoying kicking Gould around.
posted by orthogonality at 4:24 AM on December 30, 2005


"Lynching" is a pretty strong term, but I'll assume you meant it metaphorically, to denote an attack on Wilson's reputation. The last time I checked, E O Wilson's reputation was in no danger from anybody, least of all Gould.

This all strikes me as so much sectarian squabbling. One side nitpicks the other sides metaphors until they can find a satisfying case for criticism. Once they have that, they can rise up on their hind legs like a bunch of little Rory Calhouns and yap across the imaginary sectarian boundary.

If you take apart the argument that's being made in the lead link, it doesn't say anything that anybody (not counting Creation Scientists) wasn't already supposing, just without putting it in terms of some specific physical model.
posted by lodurr at 4:40 AM on December 30, 2005


Gould and Lewontin "The Spandrels of San Marco and the Panglossion Paradigm"* is probably the greatest and most important evolutionary-ecology paper published in the last century. So leave the man be.

* Gould and Lweontin (1979) The Spanrels of San Marco and the Panglossian Paradigm: A Critique of the Adaptationist Programme. Proceedings of the Royal Society of London, Series B, 205 no. 1161, 581-598.

evolutionary theory is a very quarrelsome field at the best of times

...a fact that should be shoved in the face of creationists at every opportunity. Biologists are no longer arguing about whether evolution is real. They haven't been for a century. Instead, we're arguing about the details, and efforts to drag us backwards are insulting and ignorant.

Enough of my gripes. These Gould/Maynard-Smith/Dawkins debates (and the Grime/Tilman debates, for that matter) are all fun and games, but I'm going to delve into the link, now.
posted by Jimbob at 4:44 AM on December 30, 2005


One side nitpicks the other sides metaphors until they can find a satisfying case for criticism.

Debates like these are great fun to delve into (well I find them so), but it is rather dissapointing, to see scientists combat each other not with experiments and analysis but with personalities. One has to wonder how seriously they take it - if the animosity moves beyond academic debate and into personal life, then it shames us all.
posted by Jimbob at 4:49 AM on December 30, 2005


This explains why all those exotic species taste like chicken.
posted by dances_with_sneetches at 5:17 AM on December 30, 2005


... if the animosity moves beyond academic debate and into personal life ....

I know that in some cases it does, and in others it doesn't. There are many examples of intellectual rivals who enjoy one another's companies; there are also many examples of scholars who guard their grants so fiercely that they'll work politically to hurt their rivals, who they see as competitors for funding.

And then there are still other cases where the battles get personal, for whatever reason, without there being any real financial motivation. It just means they're human.

What irritates me most is when the elders are pitted against one another by lesser lights in a sort of proxy battle. People hitch their wagons to a star, and rather than taking a controversial position on their own (hard enough to do if you have to do difficult, expensive research) they talk up the position of their de facto guru. I've had the impression that the Gould-Wilson conflict was something like this. Both are (were) eloquent, personable men of diverse interests with the respect of their peers, and an intellectual conflict between their views should have been, and probably was, useful. But the fact that people can feel the desire to poke one or the other with a sharp stick in 2006 says to me that the conflict passed beyond the intellectual realm into the political, and often the emotional.

.... why all those exotic species taste like chicken.

... or sneetch. [evil /]
posted by lodurr at 5:22 AM on December 30, 2005


This would be a much more interesting article if it included just the a teeny-tiny little itty bit of math showing what this splendid function looks like.

*sigh*
posted by warbaby at 5:57 AM on December 30, 2005


So, on the grand scale, if it walks like a duck and quacks like a duck, there's a very good probability that it is not a duck?
posted by weapons-grade pandemonium at 5:59 AM on December 30, 2005


According to most major governments, that is exactly the case. We cannot, after all, trust what our senses or feelings tell us- the media is right. The media is always right. Calling people's attention to the topic of ID v.s evolution (I do not want to start an argument) if evolution appears to be the case, and conclusive evidence shows that evolution is what occurs in nature, somehow this contributes to an ID argument. Don't ask me how.
posted by malusmoriendumest at 6:44 AM on December 30, 2005


Gould also led the lynching of EO Wilson. For that, Gould deserves whatever kicking around we can give him.

that seems quite a strange statement so i need to ask why?
because Gould criticised Wilson's writings and concepts doesn't mean that we should dismiss Goulds ideas outright (and give him that metaphorical "kicking"). Wilson is a great guy, i'm a big fan, but the last thing Biology needs is personality cults
(for example, PCR is a technique used everyday and quite essential to Biology today - it doesn't mean i'm going to outrightly accept the blatherings of Kary Mullis)
posted by tnai at 6:57 AM on December 30, 2005


This is a great article, and a fascinating finding. I especially liked the reasoning about the fish and gravity toward the end.

As to Gould: Although I understand his use of the notion of contingency, I'm not sure that this finding so directly contradicts it. His essays on things like the panda's 'thumb,' for instance, suggest that there is plenty of room for physically optimum structures to arise because they are optimum. I'm not sure that saying that evolution would follow a different set of paths is the same as saying that there would be a completely different set of outcomes, that physical laws would not apply.

And, orthogonality, I know I don't have to tell you that nothing about this article validates sociobiology. Bashing this part of Gould doesn't any of that debate.
posted by OmieWise at 6:58 AM on December 30, 2005


Biologists are no longer arguing about whether evolution is real. They haven't been for a century. Instead, we're arguing about the details

exactly. if anyone is interested, Dawkins and Coyne write about some of the real controversies in evolution in this article.
posted by tnai at 7:00 AM on December 30, 2005


could someone with a great interest but a moderate amount of knowledge (read gould, diamond, wilson, etc) fill me in on the gould vs. wilson debate?

also, this might be a slight hijack, but what are some other good overviews/books of evo-bio for the layman?
posted by yonation at 7:01 AM on December 30, 2005


ach - that is, could someone with a lot of knowledge fill *me* in, me with the great interest but moderate knowledge...
posted by yonation at 7:02 AM on December 30, 2005


...a fact that should be shoved in the face of creationists at every opportunity. Biologists are no longer arguing about whether evolution is real... Instead, we're arguing about the details

Unfortunately, creationists tend to interpret that as "they can't even agree among themselves how it works". I happened across a "christian" section of a bookshop the other day (it was across from the "music" section for some reason) and was amazed how many "reclaim science" type books there were, making arguments that evolution, global warming, cloning, and various other avenues of science were all part of the same secular conspiracy...
posted by mdn at 7:37 AM on December 30, 2005


OmieWise writes "And, orthogonality, I know I don't have to tell you that nothing about this article validates sociobiology. Bashing this part of Gould doesn't [advance? apply to?] any of that debate."

You're right, of course, but it's more evidence that Gould, while a brilliant writer, was a poor scientist. He got a lot wrong: punctuated equilibrium, the Cambrian "explosion", contingency, and his fanatical stance against sociobiology. And much of what he got wrong seems to have been influenced by his Marxist beliefs.

Gould pretty strongly and consistently advocated general contingency even if he admitted that evolution would find local optima; and he argued if evolution were done over, the results might be completely different. The locomotion study I think shows that, given the same gravity, certain things -- i.e., locomotion -- can not be different, so I say it's a shot across Gould's bow.

And the way he went after Wilson, smearing him to the point where Wilson was shouted down and physically attacked, is just so beyond the pale. Read Segerstrale's book (see below) -- it's not especially partisan toward either, but the unvarnished truth suffices to effectively damn Gould.

And I agree, these general strictures on development are fascinating.


yonation writes "the Gould vs. wilson debate?"

A long and complex but very readable account (it's a page turner, really) is Ullica Segerstrale's Defenders of the Truth.
posted by orthogonality at 7:39 AM on December 30, 2005


I'm still unclear on how contingency is undermined by the existence of "local optima" -- or even generalized optima. "Contingency" does not imply randomness. It implies the existence of chance, which is kind of hard to argue with.

At a theoretical level -- discarding the political context of "who's a marxist and who's a better marxist", e.g., Lewontin v. Chomsky -- it's very easy to reconcile a lot of these problems. It's when the issue is understood at the political level that the problems arise.

As for Gould's alleged offenses against Wilson, they still ought have no bearing on a discussion of the merits of theory. "Kicks" ought not enter into it, unless we're discussing either ethics or the social history and historiography of science, and I'd like to think that wasn't supposed to be the point of the posts.
posted by lodurr at 7:59 AM on December 30, 2005


stultifies?
posted by blue_beetle at 8:13 AM on December 30, 2005


warbaby, try this. Lots of math in that one.
posted by Grod at 8:15 AM on December 30, 2005


Curiously, do you suppose this same theory would somehow account for the need by certain species to base their existence upon supernatural forces?
posted by deusdiabolus at 8:16 AM on December 30, 2005


Grod writes "warbaby, try this. Lots of math in that one."


The whole thing is free?
posted by orthogonality at 8:17 AM on December 30, 2005


Well, I've never read Gould's work, maybe that's a good thing. The stuff they talked about here seemed pretty common-sense, that there would be one 'ideal' amount of strength used in flight, or walking.

Its like how most walking animals have a 'natural speed' related to the pendulum speed of their legs. Evolution is going to evolve toward an ideal, not away from it.
posted by delmoi at 8:35 AM on December 30, 2005


No, no, no!

Evolution doesn't evolve toward anything. It just eliminates organism that are less fit.

In fact, evolution of a particular trait often does stop when it reaches "good enough": e.g., Baldwin Effect. As the simulations show, the real evolutionary value of the Baldwin Effect, is that it gives good (but not too good) genes...."
posted by orthogonality at 8:41 AM on December 30, 2005


My back rubbing skills have ceased to evolve. They must be good enough enough.
posted by maxsparber at 8:55 AM on December 30, 2005


Do I stutter?
posted by maxsparber at 8:55 AM on December 30, 2005


It doesn't really work against Gould's conjecture that there are general physical constraints on the movement, speed, etc. of organisms. Yes, survival may require speed to elude predators, but... "It doesn't matter whether the animal has eight legs, four legs, two, even if it swims with no legs." They provide an envelope within which the details are (contingently) filled in.
posted by lathrop at 9:12 AM on December 30, 2005


This explains why all those exotic species taste like chicken.

I thought they all tasted like dinosaur?
posted by wah at 9:28 AM on December 30, 2005


I wonder which fictional creatures this rules out.
Is the vermicious knid forsaken?
Is it goodnight for Phillip Pullman's wheeled, square cows?
Is Cthulu terrifying because he offends terrestrial mathematics?
posted by putzface_dickman at 9:40 AM on December 30, 2005


I read last week that you have to push 14 pounds of air out of the way for every square foot of anterior surface area when you take a step. I can't say that it's true, but it's interesting.
posted by putzface_dickman at 9:44 AM on December 30, 2005


Um, this doesn't invalidate Gould at all. How do you interpret Gould's argument to mean that the universal laws of physics would not supervise evolutionary processes? IIRC, Gould's "contingency" argument was simply a restatement of the well-known principle that evolution has no "direction" and more complex organisms are not "better" than less complex organisms in any meaningful sense.

evolution would find local optima

This isn't true at all. Biological evolution doesn't find the optima of anything. Exactly what do you think is being optimised? And how can 'evolution' find anything? Do you think it's a single coherent or intelligent process analagous to, say, Newtonian's model of gravity? On the face of it, this seems like a total nonsense statement. The fact that species have evolved mechanisms to reduce the expenditure of energy lost to movement says absolutely nothing about the essential nature of evolution. Should we just discount and ignore all the cases where evolution didn't result in so-called local optima? These sorts of wild leaps of the imagination are fine, but don't pretend they're anything more than fantasy. Please don't project your wishful thinking on to science.

The locomotion study I think shows that, given the same gravity, certain things -- i.e., locomotion -- can not be different, so I say it's a shot across Gould's bow.

Not really. Let's assume--even though it's an enormous assumption--that it is the case that all species in all times and all places will meet the criteria of the given formula. (How you can make this assumption, based only on a study of mechanical motion on the planet Earth, I don't know, but let's take it as a given. I'll have to investigate this further but, on the face of it, I don't see how these guys get away with insisting that their law is indeed a bonafide universal law of physics. I suspect the reason they're so insistent on this fact is precisely because it's not clear at all how a universal law of physics can be universal when it doesn't involve universally identical elements like electrons or point masses. I see a lot of handwaving on this point in the article and it definitely isn't obvious.) Now it seems such a principle would be analagous to a principle that states that all species in all times and all places will evolve to respect the law of gravity or a principle that states that no species will ever evolve whose land speed exceeds that of light. In other words, it seems this principle will allow you to set some descriptive limits on any species as physical beings but it provides no information about the evolutionary mechanism itself. Thus, there could be two evolutions, an A1 evolution which is totally contingent and a B1 evolution which isn't, and both would produce end results in accordance with this principle and yet be totally different in every other way. In fact, I would make the stronger argument that, in the case of an evolutionary process guided by some sort of deity (which is what I suspect you really want anyway), the principle is a null statement.
posted by nixerman at 10:01 AM on December 30, 2005


Mutation tends toward efficiency. Duh.
posted by Smedleyman at 11:09 AM on December 30, 2005


nixerman writes "On the face of it, this seems like a total nonsense statement.[...] These sorts of wild leaps of the imagination are fine, but don't pretend they're anything more than fantasy. Please don't project your wishful thinking on to science. "

nixerman, I really appreciate your contribution (not only because it supports my own understanding). At the same time, I find that these kinds of rhetorical additions end up diminishing discussion. orthogonality may be wrong (I'm not saying he is, but he may be), but he's discussing this in good faith. It's so hard to read tone here and there is already so much sniping back and forth, that it would really be nice to confine it to the places where people seem to feel it cannot be avoided. Just to be clear about my own tone: I'm neither trying to scold you nor to be excessively moarlizing, just stating a preference about a couple of lines that really stood out in what I read as an otherwise stellar comment.
posted by OmieWise at 11:14 AM on December 30, 2005


I'm no friend of Gould, but I don't see how this relates to his contingency thesis. This "universal law of locomotion" seems to be incredibly broad and permissive if it can account for the movement of amoebae, humans, and jet engines. There's still plenty of room for contingency. The law seems to clamp down on potential phylogenetic pathways in the same way that other staples of the biological environment - like gravity or the presence of heat - clamp down. The contingency thesis surely isn't challenged by gravity, and I don't really see what's different about this locomotion theory.

Nixerman's post is very good. Hostile, but good.
posted by painquale at 11:25 AM on December 30, 2005


This would be a much more interesting article if it included just the a teeny-tiny little itty bit of math showing what this splendid function looks like.

Well, they have a truly marvelous demonstration of this function; however, due to poor web design, the margins are too small to contain it.
posted by MikeKD at 11:36 AM on December 30, 2005


OmieWise, I use the term 'nonsense' in the philisophical sense, as in the statement literally doesn't make sense (to human beings). It's not meant as an insult. As for my other comments they're not meant to be hostile. I'm sorry if it comes across like that. I have a lot of respect for orthogonality and I very much look forward to his various evolution posts. He does seem to have a "moralistic" view of evolution--which is why I so often end up disagreeing with him--but he's also rather knowledgeable about the subject and is always interested in learning more so discussions are usually enjoyable. You can't hear it of course, but my comments are usually made in a 'sporting' tone rather than an outright agressive tone.
posted by nixerman at 11:48 AM on December 30, 2005


From the article: "From simple physics, based only on gravity, density and mass, you can explain within an order of magnitude many features of flying, swimming and running," added James Marden, professor of biology at Penn State.

Within an order of magnitude? WTF?
posted by neuron at 11:48 AM on December 30, 2005


Smedleyman: Mutation tends toward efficiency. Duh.
Efficiency is contextual. Efficient at what? To what end? Relative to what?

Certainly if you look at what the evolved system (e.g., an organism) ends up doing, then by definition it will evolve to be efficient. Is that what you mean? Something on the lines of "things are what they are, duh"?
posted by lodurr at 12:00 PM on December 30, 2005


nixerman writes "You can't hear it of course, but my comments are usually made in a 'sporting' tone rather than an outright agressive tone."

Excellent, that was my hope, thanks for clarifying.
posted by OmieWise at 12:01 PM on December 30, 2005


Put another way: If you work backward from the result, the result is always going to seem inevitable (or efficient). If you work forward, you will always be dealing in probabilities (i.e., contingencies); the probabilities are constrained by physics. No conflict with any hypothetical universal law of locomotion.
posted by lodurr at 12:04 PM on December 30, 2005


I appreciate Omiewise's call for civility. But I don't really take nixerman's over-the-top stuff personally; like OmieWise, I'm glad to see him contributing to the conversation and to our understanding.

There are a couple of places, though, where either nixerman is really misunderstanding me, or I'm really misunderstanding him:

nixerman writes "in the case of an evolutionary process guided by some sort of deity (which is what I suspect you really want anyway)" and "He does seem to have a 'moralistic' view of evolution-".

I'm not looking for any deity, and while I may be moralizing about Gould's treatment of Wilson, I don't think my view of evolution is moralistic.

The reason I like evolutionary psychology (sociobiology) is that it has great explanatory power: in brief, if you want to understand what Man is, understand the environment in which Man evolved, and treat Man as a biological machine adapted by evolution to be fit in that environment.

The other thing I like about that, is that it moves even farther away from the Creationist idea of Man as a "special creation", separate from "the animals". Wilson (and the evo. pysch. folks) are just saying, examine Man as you'd examine any other animal. Nothing special at all: if Bower Birds, Beavers and Bees have evolved behavioral "tricks", some of them stereotyped (a beaver confined to a bare cement enclosure will nevertheless go through the motions of building a dam), the sociobiologists are saying, "look to see what "tricks" man has evolved, and expect many of those to be unconscious and stereotyped. Yes, man can talk and reason, but those aren't "special" those are just (perhaps more elaborate or more elaborated) "tricks".

I'm definitely not looking for a Creator, or any "morals" in evolution! (Nor am I looking to use evolutionary theory to justify any political or moral scheme; as OmieWise pointed out in the torture thread, morals are just about things being wrong, regardless of efficacy.) I just want to see biological machines, doing (reductively) tiny, simple things, governed by physical laws.

I want that because it's not "special", it requires no gods or souls or magic, just matter in motion. Which makes it clean and elegant and self-sufficient -- and beautiful.


As to the linked article, of course I liked it because it's got that genericity : no animal is "special": all are governed by the same constraints. It's more than just as empty as, as nixerman claims "a principle that states that no species will ever evolve whose land speed exceeds that of light" -- it's a formula that shows an upward bound of work done for all sorts of specialized forms of locomotion, regardless of their material construction to a few simple factors,. And it even works for human built machines, like jet planes. I love it for its utter lack of any call for "special creation" or "special rules".
posted by orthogonality at 12:25 PM on December 30, 2005


Well, it's a self-link, but the Gould/Dawkins etc controversy is covered in some depth in my book the Darwin Wars. I don't know what GHould made of it, but it was nicely reviewed by his chum Steven Rose, and Dawkins thinks its fair to his ideas.
posted by alloneword at 1:05 PM on December 30, 2005


Well, it's a self-link, but the Gould/Dawkins etc controversy is covered in some depth in my book the Darwin Wars. I don't know what Gould made of it, but it was nicely reviewed by his chum Steven Rose, and Dawkins thinks its fair to his ideas.
posted by alloneword at 1:08 PM on December 30, 2005


It seems to me this is a question of scale. Contingency must exist on a moecular level. There are other nucleoside bases and amino acids that could have been used in DNA, RNA and proteins. Especially if one considers life evolving in a slightly different molecular environment. However, if you agree with their findings contingency does not exist on the organismal scale with regards to parameters of locomotion. Interesting, but not all that stunning.
posted by batou_ at 1:19 PM on December 30, 2005


Gould is on record as stating that sea life may not ever get out onto the land in repetitive evolutionary Earth trials.

This is one of the stupider conjectures I've seen in science.
posted by Heywood Mogroot at 1:19 PM on December 30, 2005


alloneword writes "the Gould/Dawkins etc controversy is covered in some depth in my book"


I liked you on CNN. Sorry you got bumped for Gloria Vanderbilt's kid. If you send me a free copy of your book, I will send you a free Firefox extension.
posted by orthogonality at 1:22 PM on December 30, 2005


Duur, that was JM Smith:
In Gould's "replay from the Cambrian" experiment, I would predict that many animals would evolve eyes, because eyes have in fact evolved many times, in many kinds of animal. I would bet that some would evolve powered flight, because flight has evolved four times, in two different phyla; but I would not be certain, because animals might never get out on the land.
apologies to the Gould
posted by Heywood Mogroot at 1:24 PM on December 30, 2005


“Certainly if you look at what the evolved system (e.g., an organism) ends up doing, then by definition it will evolve to be efficient. Is that what you mean? Something on the lines of "things are what they are, duh"? “- posted by lodurr

The strongest survive. Duh.

Yea. The whole concept in the peice seemed recursive.
More or less what you said: “If you work backward from the result, the result is always going to seem inevitable (or efficient).”

Seems to be the flaw in explicating those kinds of “strongest survive” ideas. Well, no shit, if they survive, then they were the strongest.
posted by Smedleyman at 1:40 PM on December 30, 2005


This discussion made me think of Wolfram's "A New Kind of Science." Here is a discussion of Gould's "sea shell" dissertation and a broader discussion of Wolfram's ideas and Darwinism.
posted by sp dinsmoor at 4:00 PM on December 30, 2005


I've often wondered what things would be like if nature invented the wheel. I'm imagining creatures with flywheels for hearts and wheel joints.
posted by Dag Maggot at 4:22 PM on December 30, 2005


Dag Maggot writes "I've often wondered what things would be like if nature invented the wheel."


Google on this, and you'll see that the IDers wonder about it too.
posted by orthogonality at 5:00 PM on December 30, 2005


Dag Maggot - I've often wondered what things would be like if nature invented the wheel.

Nature did invent the wheel. Motile bacteria have a flagellar connected to a rotory motor.


posted by Meridian at 5:17 PM on December 30, 2005


Heywood Mogroot: Gould is on record as stating that sea life may not ever get out onto the land in repetitive evolutionary Earth trials.

This is one of the stupider conjectures I've seen in science.
[doubletake /] Ummm.....why? Seriously, what's stupid about that? It sounds like probability 101 to me: The dice may never come up snakeeyes. (But probably will.)
posted by lodurr at 5:18 AM on December 31, 2005


..."The question was: How could a theory including gravity apply to swimming fish?" Marden said.

...Although fish are neutrally buoyant, they still have to push water out of the way to move forward, he said. That water raises the surface – a phenomenon that is often imperceptible as it may be spread across an entire lake, stream or ocean.

"The water can only go up because the bottom and sides of the channel are rigid," Bejan said. "That bulge, however undetectable, is the fish's footprint."

Fish must, therefore, work against gravity to lift an amount of water equal to their own mass for each body length they move forward.


Ehm... not exactly. They have to displace an amount of water with equal volume as theirs. This implies a mass equivalence only if their density is the same (which I presume it more or less is). And "lifting" is wrong. The same effort would be required even if the fish swam in a container with all walls fixed. More importantly, thinking about it, I wonder if the researchers imply that density (of water) is proportional to the work required - I think not. I'd guess that viscosity is the major factor here, and so is the "shape" of the fish... so either the article oversimplifies or something else is meant here that I can't understand...

And I can't see how this has anything to do with Gould's contingency. Here's a related essay of Gould's in which he acknowledges that of course the physical constraints are important...
posted by talos at 5:27 AM on December 31, 2005


I've often wondered what things would be like if nature invented the wheel.

doesn't a wheel have to be separate from the axle? if a creature like a mammal were to have a "wheel", it would have to have its own circulatory system, etc, wouldn't it? maybe some kind of osmosis thingy between the rotating part and the axis could make it one animal, but it'd be a lot more complicated than walking limbs, and a lot less useful (people in wheelchairs are generally less able than people with legs...). Wheels are good for moving around dead weight, but for a self motivated animal, they wouldn't be much of a plus.
posted by mdn at 1:38 PM on December 31, 2005


The wheel could be non-living material, like a fingernail, or antler that doesn't need a circulatory system.

Wheels for locomotion might not be that efficient, but I bet it could be useful for internal organs - particularly pumps.
posted by Dag Maggot at 7:26 PM on December 31, 2005


what are some other good overviews/books of evo-bio for the layman?

i'd recommend "what evolution is" by Ernst Mayr.
PZ has a good evolution book list here.
posted by tnai at 9:56 AM on January 1, 2006


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