Posted By Caulimovirus on April 24, 2007
“Evolution and the Song of Creation”
.: I just returned from a lecture given by Simon Conway Morris called, “Darwin’s Compass: How Evolution Discovers the Song of Creation.” I read about it in today’s Lariat, and the fliers in the science building certainly piqued my interest:
ABSTRACT: Is evolution a random, open-ended process without inherent predictability? â€œRerun the tape of life,â€ claimed Stephen J. Gould and the outcome will be entirely different: no humans, for example. I will argue the exact reverse. Evolution is far more predictable than generally thought, whether we are talking about molecules or societies. This means human-like intelligence is very probable, perhaps inevitable. So this not only indicates a deep structure to evolution, but also reopens the question posed by Fermi: where are the extraterrestrials?
.: I was skeptical about his conclusions before going, and I remain so, but the talk was certainly interesting, and I appreciate some of the things he said.
.: Before the lecture started, I made a little bet with some friends:
Me: I’m going to keep a tally for every mention of Stephen Jay Gould and Richard Dawkins; who do you think he’ll mention more?
Friend 1: I’m thinking Gould. He’s mentioned right there in the abstract, and it’s mainly his science that Conway Morris disagrees with.
Friend 2: Me too. Gould seems far more likely.
Me: Ah yes, but keep in mind we’re at Baylor. He might tailor his talk to fit the audience, and mentioning Dawkins in a negative fashion will surely work to his favor.
.: From what little research I did beforehand, I know that Conway Morris is a theistic evolutionist who latest book, Life’s Solution: Inevitable Humans in a Lonely Universe, argues against both Gould’s and Dawkins’s views of evolution. For Gould, evolution is all about contingency and expansive diversity with no possible chance for predictability of outcomes. For Dawkins, modern evolutionary theory undercuts the most powerful arguments for the existence of a creator God. Throughout the talk, Gould’s views were more often critiqued than Dawkins’s, who was barely mentioned. (The final tally, by the way, was two for Dawkins and six for Gould.)
.: The whole of his lecture consists almost exclusively of one fascinating topic: evolutionary convergence. That is, two different lineages independently evolving similar traits. Birds evolved from a wingless ancestor, as did Bats. Of course, bats did not get their wings from birds; they simply evolved on their own. Conway Morris argues that convergence is a predictable consequence of certain constraints inherent in evolution. For example, the vast majority of possible configurations of a certain trait or pathway simply won’t work. He gave one example of trying to reach a certain protein sequence where there are 120 possible mutation pathways. Of the 120, only 18 are viable. The other 102 are non-possibilities. If that protein served a basic life function, such as capturing a stray election for energy or breaking down a common molecule, then, he argues, you would expect to see it over and over again in distinct lineages.
.: As for running the tape of life backwards, Conway Morris concedes that if certain historical events were changed — say, a stray asteroid didn’t hit the earth 65 million years ago — then of course we’d see something different today. But he argues what we would see would have several similarities with what we have today. A few of the features he covered in depth were the following:
Eyes. Both fish and cephalopods have camera-like eyes, which superficially resemble each other a great deal. Both types of eye have transparent lenses and retinas, and both evolved independently — another remarkable example of convergence. Yet he was also quick to point out some major differences. The cephalopod eye has the photoreceptors on top of its blood vessels, while the vertebrate eye has it backwards (a somewhat clumsy arrangement, actually — imagine having thin red lines painted all over your car’s windshield). Also, in vertebrate eyes, the nerves all converge into one stalk (the optic nerve) as they travel to the brain; in cephalopod eyes the nerves are more like roots, which consequently restricts eye movement.
.: Conway Morris seems to be willing to ignore these differences and suggests that evolution approaches a more idealistic, “platonic” form of the eye. Never mind the small differences, he argues, it’s the big picture that’s important. The basic scheme of the camera eye is incredibly effective and therefore it’s unsurprising to see it appear in nature more than once. It’s certainly true that the camera-like eyes create a more detailed picture of surrounding environments than the compound eyes of insects and other such creatures, but there are many independently evolved compound eyes as well, and species with such eyes seem to be doing perfectly fine here on Earth.
Limbs. He showed a slide of octopus tentacles and a human arm, noting that they “couldn’t be more different” in appearance. But in terms of behavior, one can easily see convergence: octopuses, by means of special electric signals, create an artificial three-sectioned arm comparable to that of a human arm. Why does it do this? Because it turns out the three-sectioned limb is the more efficient setup, mechanically speaking. To me, this really stretches the concept of convergence. (You’ll thank me for avoiding any “out on a limb” puns here.) In a sense, evolutionary processes certainly can find idealized forms for mechanical structures. An example that immediately springs to mind is the structure of blood vessels, which Richard Dawkins mentions in this clip from The Blind Watchmaker (fast forward to about 4:10).
.: But tentacles and arms are still very different things, despite this one mechanical similarity. I think it’s safe to conclude that, in another world, the three-sectioned limb will surely show up here and there, but if something as distinct as an octopus’s tentacle is considered convergent with a human arm, then Conway Morris’s “inevitable humans” are an amorphous lot indeed.
Teeth. Two different lineages of mammals evolved saber-teeth: one was a placental mammal, the other was a marsupial. Eutheria and Metatheria diverged quite a bit ago, but these particular saber-toothed species closely resemble each other to an uncanny degree. This one isn’t as impressive as the the camera eye example; it’s actually quite mundane. These are just two animals whose ancestors walked around on all fours biting other animals to death. Those same ancestors also independently evolved larger teeth so they could more easily bite other animals. Okay. And other animals didn’t evolve crazy-large teeth.
.: Conway Morris wants to argue against the idea that humans are mere flukes of evolutionary history — my guess because he doesn’t like the implicit denigration of our species as “nothing special” — and he does so by pointing out several motifs in life’s history, then concludes that human-like creatures must result from an evolutionary process. After all, certain features of humans appear in other animals, so it’s inevitable that if the tape of life were run again all those features would coalesce into a roughly humanoid figure. But at the same time, compound eyes, segmented bodies, and wings all independently evolved in other lineages. Why bother singling out humans? His book might as well be subtitled Inevitable Dragonflies in a Lonely Universe.
.: All of that said, I really did enjoy most of the talk. Simon Conway Morris is an engaging speaker, and he’s really quite funny to boot. He was also careful to point out directionality and predictability in evolution need not at all imply teleology. We’re in the natural world; things are going to operate by natural law, so he reasoned. This was significant, I thought, because there was a special guest visitor in the audience which made the quote all the more appropriate: William Dembski.
.: I was actually quite impressed by Dembski’s appearance: not once during the entire presentation did he make a single fart noise. He even got to ask a question, too! It was something about the convergence in the pre-biotic world, and how Conway Morris was overstating the case on abiogenesis and blah blah blah western science has abandoned God blah blah blah I don’t work at this university anymore blah blah blah why do I claim to be a mathematician when I don’t publish anything mathematical? blah blah blah my God I’ve wasted my life blah blah blah. I was hoping for more fun from Dembski, but he left before the Q&A session was over.
.: All in all, tonight was really quite a treat. Not only did I get to attend a lecture by a distinguished member of the Royal Society, but I also got to sit a mere three aisles behind one of today’s biggest intellectual losers. I wish I brought my camera.