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The Wonder of Evolution

31 Post author: Eliezer_Yudkowsky 02 November 2007 08:49PM

Followup to:  An Alien God

The wonder of evolution is that it works at all.

I mean that literally:  If you want to marvel at evolution, that's what's marvel-worthy.

How does optimization first arise in the universe?  If an intelligent agent designed Nature, who designed the intelligent agent?  Where is the first design that has no designer?  The puzzle is not how the first stage of the bootstrap can be super-clever and super-efficient; the puzzle is how it can happen at all.

Evolution resolves the infinite regression, not by being super-clever and super-efficient, but by being stupid and inefficient and working anyway.  This is the marvel.

For professional reasons, I often have to discuss the slowness, randomness, and blindness of evolution.  Afterward someone says: "You just said that evolution can't plan simultaneous changes, and that evolution is very inefficient because mutations are random.  Isn't that what the creationists say?  That you couldn't assemble a watch by randomly shaking the parts in a box?"

But the reply to creationists is not that you can assemble a watch by shaking the parts in a box.  The reply is that this is not how evolution works.  If you think that evolution does work by whirlwinds assembling 747s, then the creationists have successfully misrepresented biology to you; they've sold the strawman.

The real answer is that complex machinery evolves either incrementally, or by adapting previous complex machinery used for a new purpose.  Squirrels jump from treetop to treetop using just their muscles, but the length they can jump depends to some extent on the aerodynamics of their bodies.  So now there are flying squirrels, so aerodynamic they can glide short distances.  If birds were wiped out, the descendants of flying squirrels might reoccupy that ecological niche in ten million years, gliding membranes transformed into wings.  And the creationists would say, "What good is half a wing?  You'd just fall down and splat.  How could squirrelbirds possibly have evolved incrementally?"

That's how one complex adaptation can jump-start a new complex adaptation.  Complexity can also accrete incrementally, starting from a single mutation.

First comes some gene A which is simple, but at least a little useful on its own, so that A increases to universality in the gene pool.  Now along comes gene B, which is only useful in the presence of A, but A is reliably present in the gene pool, so there's a reliable selection pressure in favor of B.  Now a modified version of A* arises, which depends on B, but doesn't break B's dependency on A/A*.  Then along comes C, which depends on A* and B, and B*, which depends on A* and C.  Soon you've got "irreducibly complex" machinery that breaks if you take out any single piece.

And yet you can still visualize the trail backward to that single piece: you can, without breaking the whole machine, make one piece less dependent on another piece, and do this a few times, until you can take out one whole piece without breaking the machine, and so on until you've turned a ticking watch back into a crude sundial.

Here's an example:  DNA stores information very nicely, in a durable format that allows for exact duplication.  A ribosome turns that stored information into a sequence of amino acids, a protein, which folds up into a variety of chemically active shapes.  The combined system, DNA and ribosome, can build all sorts of protein machinery.  But what good is DNA, without a ribosome that turns DNA information into proteins?  What good is a ribosome, without DNA to tell it which proteins to make?

Organisms don't always leave fossils, and evolutionary biology can't always figure out the incremental pathway.  But in this case we do know how it happened.  RNA shares with DNA the property of being able to carry information and replicate itself, although RNA is less durable and copies less accurately.  And RNA also shares the ability of proteins to fold up into chemically active shapes, though it's not as versatile as the amino acid chains of proteins.  Almost certainly, RNA is the single A which predates the mutually dependent A* and B.

It's just as important to note that RNA does the combined job of DNA and proteins poorly, as that it does the combined job at all.  It's amazing enough that a single molecule can both store information and manipulate chemistry.  For it to do the job well would be a wholly unnecessary miracle.

What was the very first replicator ever to exist?  It may well have been an RNA strand, because by some strange coincidence, the chemical ingredients of RNA are chemicals that would have arisen naturally on the prebiotic Earth of 4 billion years ago.  Please note: evolution does not explain the origin of life; evolutionary biology is not supposed to explain the first replicator, because the first replicator does not come from another replicator.  Evolution describes statistical trends in replication.  The first replicator wasn't a statistical trend, it was a pure accident.  The notion that evolution should explain the origin of life is a pure strawman—more creationist misrepresentation.

If you'd been watching the primordial soup on the day of the first replicator, the day that reshaped the Earth, you would not have been impressed by how well the first replicator replicated.  The first replicator probably copied itself like a drunken monkey on LSD.  It would have exhibited none of the signs of careful fine-tuning embodied in modern replicators, because the first replicator was an accident.  It was not needful for that single strand of RNA, or chemical hypercycle, or pattern in clay, to replicate gracefully.  It just had to happen at all.  Even so, it was probably very improbable, considered in an isolated event—but it only had to happen once, and there were a lot of tide pools.  A few billions of years later, the replicators are walking on the moon.

The first accidental replicator was the most important molecule in the history of time.  But if you praised it too highly, attributing to it all sorts of wonderful replication-aiding capabilities, you would be missing the whole point.

Don't think that, in the political battle between evolutionists and creationists, whoever praises evolution must be on the side of science.  Science has a very exact idea of the capabilities of evolution.  If you praise evolution one millimeter higher than this, you're not "fighting on evolution's side" against creationism.  You're being scientifically inaccurate, full stop.  You're falling into a creationist trap by insisting that, yes, a whirlwind does have the power to assemble a 747!  Isn't that amazing!  How wonderfully intelligent is evolution, how praiseworthy!  Look at me, I'm pledging my allegiance to science!  The more nice things I say about evolution, the more I must be on evolution's side against the creationists!

But to praise evolution too highly destroys the real wonder, which is not how well evolution designs things, but that a naturally occurring process manages to design anything at all.

So let us dispose of the idea that evolution is a wonderful designer, or a wonderful conductor of species destinies, which we human beings ought to imitate.  For human intelligence to imitate evolution as a designer, would be like a sophisticated modern bacterium trying to imitate the first replicator as a biochemist.  As T. H. Huxley, "Darwin's Bulldog", put it:

Let us understand, once and for all, that the ethical progress of society depends, not on imitating the cosmic process, still less in running away from it, but in combating it.

Huxley didn't say that because he disbelieved in evolution, but because he understood it all too well.

 

Part of the sequence The Simple Math of Evolution

Next post: "Evolutions Are Stupid (But Work Anyway)"

Previous post: "An Alien God"

Comments (79)

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Comment author: Shakespeare's_Fool 02 November 2007 10:31:04PM 0 points [-]

Eliezer,

Could you -- perhaps in another thread -- discuss how "The Evolution of Cooperation" (as Robert Axelrod put it) fits or does not fit with Huxley's comment. Can Axelrod and Huxley both be right?

John

Comment author: Caledonian2 03 November 2007 12:06:56AM -3 points [-]

The wonder of evolution is that it works at all.

It's a process that, given certain rudimentary facts about existence, MUST occur. It's totally mindless, relies on trial-and-error, and is unspeakably powerful. You can't make designs better than it can - you can't even make designs as well as it can. At most, you can take incredibly complex systems it's created and point out a few places where you could put a patch to make things even better. You can do this by using a brain evolution is responsible for.

Evolution doesn't recognize your inherent 'specialness' at all. Nothing in the universe does, come to think of it, except a few other people. Almost the entirety of the universe is utterly indifferent to your existence: no stars in the sky heralding your birth, no suns dimming at your passing, no cosmic phenomena that mirror what you think, what you feel.

How that must vex you!

Comment author: jeff_gray2 03 November 2007 12:52:00AM 0 points [-]

caledonian

evolution is contingent. so are we. what's your point?

Comment author: Peter_de_Blanc 03 November 2007 12:52:21AM 12 points [-]

Caledonian, in reply to the first half of your post: some of evolution's designs are quite impressive, yes. They took billions of years to produce. Just wait until we've had a billion years to design stuff - then you'll be really impressed.

Also, your taunting is not useful. Stop it.

Comment author: Nick_Tarleton 03 November 2007 02:48:39AM 10 points [-]

What evolutionary algorithm, operating over a non-immense period of time, even comes close to what a talented human is capable of? It wasn't evolution that built your computer, although small parts of it (that humans are unusually bad at designing) may have been constructed by evolutionary algorithms.

Humans are also functions of reality, unless you're a dualist. We have imperfect models, but evolution doesn't have a model at all, which is why it's stupid. Even if it did inerrantly respond to the immediate environment (and it doesn't - look at the effect of a sense of taste adapted to a very different environment, for instance), it necessarily can't plan for the future. You really sound like you're genuflecting at a sacred mystery, not being rational.

Re specialness: it's annoying to smugly point out things that people are already perfectly aware of.

Comment author: Caledonian2 03 November 2007 03:19:00AM -1 points [-]

It wasn't evolution that built your computer

Which one? Because my human-built computer is inferior is virtually every way to the one evolution produced. The only real advantages the electronic model has are that it's easy to make backups for it, and people have been writing viruses for it for a shorter period of time.

We have imperfect models, but evolution doesn't have a model at all, which is why it's stupid.

Its stupidity is still smarter than the most brilliant human.

it necessarily can't plan for the future

True. But it never fails to react appropriately to the local conditions, which humans are actually quite bad at doing. Neither are we very good at planning for or anticipating the future. But perhaps you don't consider triggering the Sixth Great Extinction to reflect poorly upon humanity's ability for forethought.

it's annoying to smugly point out things that people are already perfectly aware of

It is very important to point out things that people are already perfectly aware of but choose to ignore. The annoyingness is just a bonus. And as the readers of this site are already quite aware, the methods that make thought most powerful are those that are most antithetical to natural human modes of thought: logic and mathematics. Bayes' Theorem is smarter than the humans that use it. Funny, that.

Comment author: GreedyAlgorithm 03 November 2007 08:06:19AM 3 points [-]

To stay unbiased about all of the commenters here, do not visit this link and search the page for names. (sorry, but - wait no, not sorry)

So it seems to me that the smaller you can make a quine in some system with the property that small changes in it mean it produces nearly itself as output, the more likely that system is going to produce replicating evolution-capable things. Or something, I'm making this up as I go along. Is this concept sensical? Is there a computationally feasible way to test anything about it? Has it been discussed over and over?

Maybe we can do far better than evolution, but if we could design a good parallelizable "evolution-friendly" environment and see whether organisms develop that'd still be phenomenal.

Comment author: kamenin 03 November 2007 11:29:04AM 1 point [-]

Evolution resolves the infinite regression, not by being super-clever and super-efficient, but by being stupid and inefficient and working anyway. This is the marvel.

Stupid and inefficient is sometimes much better (and faster) than a meticulously designed process. If you've ever dealt with fitting of really complex data, a random walk is often suprinsingly more efficient than any of the refined fitting algorithms. In itself it's just stupid "trial and error" in endless repetition, just like evolution, with a little bit of organizing in the background.

Comment author: Tom_McCabe2 03 November 2007 03:23:38PM 9 points [-]

"Because my human-built computer is inferior is virtually every way to the one evolution produced."

From LOGI:

"Current computer programs definitely possess these mutually synergetic advantages relative to humans:

* Computer programs can perform highly repetitive tasks without boredom. * Computer programs can execute complex extended tasks without making that class of human errors caused by distraction or short-term memory overflow in abstract deliberation. * Computer hardware can perform extended sequences of simple steps at much greater serial speeds than human abstract deliberation or even human 200Hz neurons. * Computer programs are fully configurable by the general intelligences called humans. (Evolution, the designer of humans, cannot invoke general intelligence.)"

"Its stupidity is still smarter than the most brilliant human."

Taking the earlier example of the eye, we've already surpassed it in just about every way. We have cameras which can see in much dimmer light, and cameras which can look directly at the Sun without getting fried. We have cameras that can see in radio and gamma rays and everything in between. We have cameras with higher resolution and better-quality optics. We have cameras that can actually detect the wavelength of every incoming photon, rather than being limited to the three-axis human color system. And so on and so forth.

"If you've ever dealt with fitting of really complex data, a random walk is often suprinsingly more efficient than any of the refined fitting algorithms."

See http://sl4.org/wiki/KnowabilityOfFAI. Only in AI would people design algorithms that are literally stupider than a bag of bricks, boost the results back towards maximum entropy, and then argue for the healing power of noise.

Comment author: Erik2 04 November 2007 09:59:20AM 2 points [-]

"Only in AI would people design algorithms that are literally stupider than a bag of bricks, boost the results back towards maximum entropy, and then argue for the healing power of noise."

I do not have the time to go through it now (which probably means I never will remember to do it) but I can offer a small observation.

When training neural networks, there is a very good reason why adding a random element improves the performance: it avoids getting stuck in suboptimal local minima. Training a network can be seen as minimizing errors on a surface in weight-space. This surface usually is littered with local minima of various sizes, so a deterministic training rule gets stuck while a stochastic one can get kicked out of them. Of course, one has to be careful not to add too much of a random element; this is usually done by using small steps in the training.

I do not know if this adds anything as once the training is complete, the net constitutes an algorithm that is deterministic. The point however is that optimization methods that (necessarily) rely on local information usually performs better with an element of noise.

Comment author: Mike_Johnson 05 November 2007 02:31:12AM 2 points [-]

Interesting series of articles. I like the theme.

Just a small observation-- you may define the origin of life outside the domain of evolution, but I think you could just as easily bring it under the umbrella of evolution, with discussion of replicator precursors such as chemical epicycles and whatnot. I see your point, but I think distancing evolution from such a question might be seen as 'passing the buck'.

Comment author: Nato_Welch 07 November 2007 06:55:22AM 6 points [-]

Would it be too hard to believe that the very first replicators actually went extinct several times before the right accidents occurred in the right circumstances to give rise to sufficiently hardy descendants?

Certainly, the first replicator that gave rise to us might be seen as marvelous - but the first replicator //period// may have been plain pathetic.

Comment author: Tim_Tyler 04 June 2008 09:40:39PM 1 point [-]

Dawkins agrees with Huxley.

He describes nature as "the ruthlessly cruel process that gave us all existence", and describes the process that made us as "wasteful, cruel and low".

He says that nature gave us a brain capable of "understanding its own provenance, of deploring the moral implications and of fighting against them".

He describes humanity as: "the only potential island of refuge from the implications of [evolution]: from the cruelty, and the clumsy, blundering waste."

However, there is no special reason for thinking these guys are right - either about the desirability or the realistic possibility of rebellion.

Comment author: Dov_Henis 30 December 2008 04:12:36PM -3 points [-]

Evolution is biased at genes replication routes, at their alternative-splicing-steps junctions

A. A reply to one of my posts:

"Dov, you write: Life's evolution is not random. It is biased, driven by culture.

Be sure you understand that Darwin did not say that evolution is random. He said that evolution is not random. It is driven by natural selection."

B. I never wrote anything that Darwin said. Here, again, is what I say and wrote:

Culture is the universal driver of genetic evolution

The major course of natural selection is not via random mutations followed by survival, but via interdependent, interactive and interenhencing selection of biased genes replication routes at their alternative-splicing-steps junctions, effected by the cultural feedback of the third stratum multicells organism or monocells community to their second and prime strata genome-genes organisms."

Dov Henis (Comments From The 22nd Century) http://blog.360.yahoo.com/blog-P81pQcU1dLBbHgtjQjxG_Q--?cq=1

Life's Manifest http://www.the-scientist.com/community/posts/list/112.page#578

Comment author: Nwallins 06 November 2010 01:25:22AM 1 point [-]

But to praise evolution too highly destroys the real wonder, which is not how well evolution designs things, but that a naturally occurring process manages to design anything at all.

Yes, but this "naturally occurring process" suits itself very well to automation and discovery.

So let us dispose of the idea that evolution is a wonderful designer, or a wonderful conductor of species destinies, which we human beings ought to imitate. For human intelligence to imitate evolution as a designer, would be like a sophisticated modern bacterium trying to imitate the first replicator as a biochemist.

It's certainly not a wonderful designer. But it can be an efficient way solve problems without human decisions. Human intelligence should not imitate evolution as a designer, but machine intelligence may well benefit.

Comment author: Douglas_Reay 19 February 2012 06:03:43PM 2 points [-]

There's a useful metaphor for this process, from a computing technique mathematicians sometimes use to find approximate solutions to numeric problems called "simulated annealing". Consider a graph with high points (called "maxima") and low points (called "minima") like this one:

IMAGE

Sometimes you know the equation, and can just solve it. But, at other times, the situation is like having a black box with some dials to twiddle, and a single output (which you want to be as big as possible). One way to search for the dial setting that produce the biggest output would be to set the dials all to zero then start systematically searching through all the possible settings, but that might take years. If the graph is simple, you can usually find the answer much faster by noting how large the output is for ten different random settings, then concentrating your search near the random setting that had the largest output and making some smaller random changes, narrowing down on the best of those, and then making some last very small changes to fine-tune your solution. This process is known as "simulated annealing" and the amount of random noise you use to vary the solution at each stage is known as the 'temperature'. You start off at a high 'temperature', making big random jumps, then slowly cool things down, making smaller and smaller changes:

IMAGE

If you lower the 'temperature' too fast, you can get stuck at a local maxima. To make the shift to a different maxima (perhaps a higher one), you'd have to increase the 'temperature' again.

Dawkins goes into details in his book "The Greatest Show on Earth" about how DNA isn't a blueprint - rather it is a series of instruction on how to do 3D origami. And the earlier an instruction is in the sequence, it harder it is to vary yet still come up with a functional end shape. (This is why there are local maxima that evolution finds it difficult to vary away from to perhaps better solutions that a designer could have found - such as not routing a nerve in a Giraffe's neck down via the heart before returning half way back up it again.)

Comment author: Ghazzali 26 April 2012 06:57:55PM 3 points [-]

If all science must be in theory falsifiable, and evolution is good science, can you give me some parameters or predictions that if they were found to be true would hurt the theory of evolution?

What would scientists need to find in the future that would seriously do damage to the theory?

Comment author: Desrtopa 26 April 2012 07:08:22PM *  12 points [-]

The standard snappy answer to this one is "fossil rabbits in the precambrian".

More generally, if we found fossils of organisms with complex adaptations which reliably dated to a time before those adaptations could plausibly have occurred (because the necessary precursors didn't exist,) then that would be a strong indication that our understanding of the development of species is wrong.

Comment author: faul_sname 26 April 2012 07:12:31PM 4 points [-]

Any number of things. One example would be traits appearing in advance of conditions that would make them favorable e.g. a deep ocean fish developing legs or a reptile developing wings while it is too heavy for the wings to increase the length of its jumps. Another would be one species adopting traits of another through direct transfer of genes, rather than through separate evolutionary lines e.g. a snake using a variety of venom that was previously only in spiders.

I could probably come up with several hundred examples, if you really needed that many. None of them are particularly likely though: there is a huge weight of evidence behind modern evolutionary theory, which means it is almost certainly true.

Comment author: thomblake 26 April 2012 08:29:53PM 10 points [-]

There is at least some sense in which the general pattern of evolution is not falsifiable - but to precisely that extent, it's not science. There is a mathematical certainty that an evolution-like process would occur in a system with random heritable changes that can selectively help or hinder reproduction. For a theist to deny evolution exists in general, they would have to insist God actively stops it from happening every day (or deny that random heritable mutations occur, or deny that they can help or hinder reproduction).

Comment author: [deleted] 26 April 2012 08:43:32PM 2 points [-]

There is a mathematical certainty an evolution-like process would occur in a system with random heritable changes that can selectively help or hinder reproduction

But this doesn't make it unfalsifiable, strictly speaking, because it can still be tested like any other empirical claim, similar to how one might "test" 2+2=4.

Comment author: thomblake 27 April 2012 01:40:04PM 1 point [-]

Sure, that.

Comment author: Bugmaster 02 May 2012 10:50:44PM 1 point [-]

Thus, finding some evidence that random mutations are not actually random, but part of some global pattern, might reduce our confidence in the theory of biological evolution (as per Ghazzali's original challenge, above).

Discovering evidence for some sort of Lysenkoism would also work, but might be harder to achieve, since all the evidence we'd found so far points in the opposite direction.