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Galapagos 2005: The Woodstock of Evolution
« on: 2005-06-28 09:08:39 » |
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This is Shermer's report on the recent Summit on Evolution in Galapagos.
The World Summit on Evolution - Galapagos 2005
The Woodstock of Evolution
by Michael Shermer, 2005-06-24
Charles Darwin famously described the origin of species as the “mystery of mysteries,” a phrase he cribbed from the astronomer John Herschel, whom Darwin visited in Capetown, South Africa during the five-year round-the-world voyage of the H.M.S. Beagle. The meeting happened a few months after Darwin departed the Galapagos islands, at which point he had not yet solved the “grand mystery,” despite the myth that Darwin first understood the mechanism of evolution in this magnificent archipelago. Darwin was, in fact, a creationist throughout the voyage, and did not accept evolution until he discovered natural selection a full ten months after leaving the Galapagos, when he was home working intensely on his collections. The Galapagos were an after-the-fact inspiration, and he could have kicked himself for not taking better notes while he was there.
(photo of attendees:
The World Summit on Evolution drew 210 evolutionary biologists to the Galapagos Academic Institute for the Arts and Sciences (GAIAS) in Puerto Baquerizo Moreno on the Galapagos island of San Cristóbal, hosted by the Universidad San Francisco de Quito.)
How appropriate, then, that the 2005 World Summit on Evolution was held at the very location where the Beagle first dropped anchor — Frigatebird Hill, on the coastal outskirt of the lively little fishing town of Puerto Baquerizo Moreno, on the island of San Cristóbal, one of a dozen major islands that make up the Galapagos archipelago, located on the equator and a province of Ecuador. The four-day conference (June 9th–12th) was held at the Galapagos Academic Institute for the Arts and Sciences (GAIAS), a high-tech facility flanked by low-tech homes and businesses. GAIAS is operated by the Universidad San Francisco de Quito, the host of the conference, which obtained additional support from the National Science Foundation (who paid the way for graduate students in evolutionary biology to attend), Microsoft (who provided computers and internet technology for GAIAS), UNESCO, and OCP Ecuador S.A., an oil conglomerate that provided additional funding.
I got involved in the conference planning in June of 2004, when I was on a Galapagos expedition led by U.C. Berkeley Darwin scholar Frank J. Sulloway, in which we explored the volcanic highlands of San Cristóbal. On the way home through Quito I met Carlos Montufar, the co-founder of the university who also happened to be a reader of Skeptic magazine, who invited me to speak on his campus. A year later Carlos and his colleagues turned an idea into a conference so successful that many veteran scientists, who have attended dozens of such gatherings in their careers, proclaimed this to be the finest conference they had ever seen. One even called it “the Woodstock of evolution.” It was a veritable Who’s Who of evolutionary theory, including William Calvin, Daniel Dennett, Niles Eldredge, Douglas Futuyma, Peter and Rosemary Grant, Antonio Lazcano, Lynn Margulis, William Provine, William Schopf, Frank Sulloway, Timothy White, and others.
(photo of Shermer at Pinnacle Rock:
Shermer and the pre-conference tour group visited Pinnacle Rock on the tiny island of Bartolome off of Santiago near Sullivan Bay, where Darwin visited in 1835. There were no sightings of Russell Crowe or any other masters or commanders.)
For the eight days before the conference Frank and I led a tour of the archipelago that included 14 conference members on a 120-foot three-masted sailing vessel named the Sagitta. With a boatload of scientific minds, it was an exceptionally stimulating experience, and our naturalist guide, Juan Tapia (every tour must have a licensed Ecuadorian naturalist), was put through his paces with a never-ending barrage of questions from this august group.
Day One : General Vision of Evolution
With 210 people in attendance (in a healthy blend of graduate students and professors), the conference began on a hot and humid Wednesday night with a lecture on the geological history and biological diversity of the islands by Carlos Valle, the first resident of the Galapagos to ever earn a Ph.D. This was followed by Frank Sulloway’s visually stunning presentation on his research project to document the ecological changes in the islands from his first visit in 1968 to the present (in which Frank has painstakingly hiked to the exact spots he stood decades ago so that photo comparisons are accurate and meaningful). Through before and after photos it became clear just how much damaged has been caused by such introduced species as goats, who have deforested entire mountains on some islands, thereby robbing the native species of a natural resource. Frank also debunked the myth that Darwin discovered natural selection in the Galapagos and became an evolutionist on the voyage. Darwin was a creationist from start to finish, says Sulloway, and he did not fully realize the importance of these islands until he returned home and began work on his extensive specimen collection. To his chagrin (once he became an evolutionist), Darwin realized that he had not recorded the island locations from which most of his specimens came from, and thus he had to rely on the notes taken by other Beagle crew members as well as the arch-creationist Captain Fitz-Roy.
(photo of attendees:
Frank Sulloway makes an important new discovery in the islands, Galapagos Bears, soon to be reported in his scientific paper, “The Adventures of Darwin Bear.”)
Day Two : Evidence for Evolution
The first session the following morning began with a lecture on the origins of life by Antonio Lazcano, President of the International Society for the Study of the Origins of Life and a scientist at the Universidad Autónoma de México, who theorized that there were three sources for the primordial soup: a reducing atmosphere from volcanic outgassing, high-temperature submarine vents and fumaroles, and space — the 4.6 billion-year-old Murchison meteorite, discovered in Australia in 1969, for example, was loaded with amino acids, aliphatic and aromatic hydrocarbons, hydroxy acids, purines, pyrimidines, and other chemical building blocks of life. “The evidence strongly suggests that prior to the origin of life the primitive Earth already had many different catalytic agents, polymers with sequences of nucleotides, and membrane-forming compounds,” Lazcano concluded. This prebiotic soup led to a catalytic and replicative RNA world, which led to the DNA world of today.
UCLA paleobiologist William Schopf began his commentary on Lazcano’s lecture by quoting the U.S. Secretary of Defense Donald Rumsfeld:
There are known knowns. There are things we know we know. We also know there are known unknowns. That is to say, we know there are some things we do not know. But there are also unknown unknowns, the ones we don’t know we don’t know.
Translating Rumsfeld, Schopf asked: “What do we know? What are the unsolved problems? What have we failed to consider?” Schopf answered:
We know the overall sequence of life’s origin, from CHONSP (carbon, hydrogen, oxygen, nitrogen, sulfur, phosphorus), to monomers, to polymers, to cells; we know that the origin of life was early, microbial, and unicellular; and we know that an RNA world preceded today’s DNA-protein world. We do not know the precise environments of the early earth in which these events occurred; we do not know the exact chemistry of some of the important chemical reactions that led to life; and we do not have any knowledge of life in a pre-RNA world.
As for what we have failed to consider, Schopf suggested that the “‘pull of the present’ makes it extremely difficult for us to model the early earth’s atmosphere and the biochemistry of early life.”
In the discussion period University of Massachusetts theoretical biologist Lynn Margulis, in her inimitable rapid-fire style, hit Lazcano with a point-blank question: “In your opinion what came first, cells or the RNA world?” Lazcano answered:
If you define a cell as a membrane-enclosed system, then lipids-enclosed systems assisted in the polymerization of molecules, which led to RNA. Lipids and cells came first, then the RNA world.
Next up was Mikhail Fedonkin, head of the Laboratory of the Precambrian Organisms at the Paleontological Institute in Moscow, with a lecture on evolution in the Proterozoic and Archean Eons, which extend back to more than 3.6 billion years ago and cover the first microfossils and stromatolite fossils. Fredonkin suggested that a fall of global temperatures and the oxygenation of the biosphere due to photosynthesis played a major role in the dramatic change in the availability of heavy metals that he believes were crucial in the metabolic processes that led to the evolution of complex life. This metal-rich environment served as a catalyst: “Over 70 percent of known enzymes contain metal ions as a cofactor of an active site. Fast catalyzed reactions segregated life first dynamically and then structurally from the mineral realm.” Once prokaryotes gave rise to eukaryotes (through symbiogenesis — Fedonkin supports Margulis’ theory of the origins of modern cells), life was off and running, exploding in the Cambrian with complex hard-bodied organisms.
Stefan Bengtson, from the Swedish Museum of Natural History, commenting on Fedonkin, asked “Why did the build-up to the Cambrian ‘explosion’ take so long?” Noting that 99.99999% of all living species who ever lived have gone extinct, Bengston reflected: “We do not know because we have nothing else to go on. Life is an evolutionary bush, not an evolutionary tree, but our data based on extant life induce us to prune the bush into a tree, so we need more data.”
Richard Fortey from the British Museum of Natural History was next in the lineup, in which he discussed the evidence of evolution in the Phanerozoic (from 542 million years ago till the present), emphasizing the importance of mass extinction events in resetting the direction of evolution, the importance of evolutionary arms races in driving morphological innovation, the relationship of climate change and changing geography to evolutionary change, and the extent to which evolution can be described as directional. With half a billion years of a solid fossil record, Fortey said we can track the evolutionary periods of creativity and crises. Stephen Jay Gould’s Wonderful Life stimulated a lot of new ideas about the Cambrian explosion of life, he continued, and it soon became clear that there were a huge variety of organisms difficult to classify, such as those in the Burgess Shale. But there are a number of Cambrian fossil beds, such as in China, where important phyla such as Chordata evolved. “But what does all this diversity mean?” Fortey asked.
There are today 30 living phyla. In the Cambrian, some claim that there were as many as 100 phyla, but the evidence does not support this. We now believe that morphological diversity did not explode as much as Gould originally suggested, although the explosion in evolutionary experimentation was real. By the time we get to the Cambrian, like at the Burgess Shale, the systems are very complex, such as trilobite eyes. Evolution was experimenting with many wondrous varieties, such as all the armor on the heads of trilobites.
Interestingly, despite the impact of the five biggest mass extinctions (Ordovician 439 Ma, Devonian 367 Ma, Permian 245 Ma, Triassic 208 Ma, Cretaceous 65 Ma), many organism groups passed through all of these extinction episodes safely, such as the cockroach. “What is amazing is not only the extent of loss, but how fast life bounces back,” Fortey concluded.
In the subsequent discussion session, Bill Schopf asked all the speakers the Gouldian question: if we reran the tape of life would we end up with something like what we have today? The collective response was that it depends on how the question is defined, as in “what do you mean by ‘something like’?” There is evolutionary convergence, so clearly some things would be preserved (like eyes and wings). The experiment has been run in that sense. Fortey said that such “what if” questions are meaningless, but that’s not true, since counterfactual history is a legitimate form of reasoning about cause and effect relationships.
Next on the roster was Peter Gogarten, a professor of molecular and cell biology at the University of Connecticut, who asked “Is the ‘Tree of Life’ a Tree?” When we are talking about prokaryote evolution, horizontal gene transfer between organisms allows us to understand genealogical relationships, he explained.
Over long periods of time gene transfer makes organisms existing in the same environment more similar to one another. This is most clearly seen in the case of organisms that live in environments that are otherwise inhabited by distant relatives only.
Thus, Gogarten concluded,
the boundaries between prokaryotic species are fuzzy. Therefore the principles of population genetics need to be broadened so that they can be applied to higher taxonomic categories.
Margaret Riley, a colleague of Margulis at the University of Massachusetts-Amherst, provided the commentary on Gogarten’s talk, suggesting that we need a modification of Ernst Mayr’s definition of a species to accommodate microbes. Mayr defined a species as: “A group of actually or potentially interbreeding natural populations reproductively isolated from other such populations.” The problem with applying this definition to microbes is that separate species are not truly reproductively isolated, and yet they still retain distinct features that keep them phenotypically apart. “Although horizontal gene transfer can and does occur, it does not obliterate the phenotypic groupings of organisms,” Riley concluded.
Australian botanist and itinerant surfer Geoff McFadden, from the University of Melbourne, lectured next on “Protists and Cellular Phenomena in Evolution,” opening with the semi-disgusting story of how Anton van Leeuwenhoek discovered the first protists by training his hand made microscope on his own diarrhoeal stool. Whatever it takes to get the data, I suppose, but I was glad that dinner was still hours away. Darwin apparently ignored protists, but Ernst Haeckel included them in his comprehensive tree of life, and Constantin Mereschkowsky was the first to appreciate the significance of protists in early eukaryotic evolution. A.F.W. Schimper noted that chloroplasts in plant cells very much resembled cyanobacteria, but the ultimate theoretical model was provided by Lynn Margulis: the key step was the endosymbiosis of cyanobacteria within a phagotrophic eukaryotic host, a process she calls symbiogenesis. In primary endosymbiosis, 1,000 genes were acquired by the nucleus from the incorporated cyanobacteria. In secondary endosymbiosis, there was a second round of gene transfer in which the eukaryote cell engulfs another plastid-containing eukaryote. Creationists and Intelligent Design theorists like to inquire how information can increase in a world filled with entropy and the decay of information. Symbiogenesis is one answer — incorporating the genome of other organisms. Lynn Margulis would have much more to say on this in her lecture the last day.
One of the best talks of the conference was delivered by the U.C. Berkeley paleoanthropologist Timothy White, in which he opened with a prediction made by Stephen Jay Gould in the late 1980s: “We know about three coexisting branches of the human bush. I will be surprised if twice as many more are not discovered before the end of the century.” A glance at the extant fossil record looks like Gould was right. There are at least two dozen fossil species in six million years of hominid evolution. But the bush is not so bushy, says White. The problem lies in the difference between “lumpers” and “splitters” in species classification, and the social pressures to publish extraordinary new discoveries. If you want to get your fossil find published in Science or Nature, and you want the cover illustration, you cannot conclude that your fossil is yet another Australopithicus africanus, for example. You better come up with an interpretation indicating that this new find you are revealing for the first time to the world is the most spectacular discovery of the last century and that it promises to overturn hominid phylogeny and send everyone back to the drawing board to reconfigure the human evolutionary tree. Training a more skeptical eye on many of these fossils, however, shows that many, if not most of these fossils belong in already well-established categories. White says that the specimen labeled Kenyanthropus platyops, for example, is very fragmented and is most likely just another Australopithicus africanus. “Name diversity does not equal biological diversity,” White elucidated.
White then concluded his talk with a fascinating discussion of the recent discovery of fossil dwarf humans on Flores Island in the Malay Archipelago, located on the outside of Wallace’s Line, meaning that even during the last ice age they could only have gotten there by boat. (White did note, however, that after last December’s tsunami people were rescued from large floating rafts of natural debris, so it is possible that the founding population of Flores rafted there by accident and not design.) Found in Liang Bua cave, the type specimen of Homo floresensis was dated at 18,000 years old, meaning that they had to be modern humans because all other hominid species had long ago gone extinct. But with a cranial capacity of only 300cc — about the same size as that of Lucy and modern chimpanzees — this means that they were able to fashion complex tools (and possibly boats) with tiny brains; the implication is that brain architecture, not size, is what counts for creating higher intelligence. A second published specimen put to rest the pathology hypothesis that Homo floresensis was a microcephalic human. The best evidence, says White, points to insular dwarfing, a rapid punctuation event out of Homo sapiens that led to a shrinkage of these isolated people. Such dwarfing effects can be seen on this and other islands, where large mammals get smaller (like the dwarf elephant), and small reptiles get larger (like the Komodo Dragon). The chances of any living members of this species still existing in the hinterlands of Flores are extremely remote, but some observers have noted that the indigenous peoples of Flores recount a myth of small hairy humans who descend from the highlands to steal food and supplies.
University of Cambridge professor Peter Forster, an expert in archaeogenetics, followed Tim White by showing how prehistoric human migrations can be traced by mitochondrial DNA (mtDNA) through the maternal line of modern humans. The mtDNA samples are taken through saliva cheek swabs, then dried to prevent molding before analysis is conducted in the lab. The process was first done in 1981, using the placenta of a woman in a maternity ward, and has since become a mainstay of researchers in this field. Forster outlined our migrational history over the past 200,000 years as follows: Between 190,000–130,000 years ago, a single female known formally as the “mitochondrial coalescent” but dubbed “mitochondrial Eve,” gave rise to every living human today. Between 80,000–60,000 years ago, a large population from the center of Africa migrated to all areas of Africa, as well as the area of present-day Saudi Arabia. This migration may have taken two routes, a northern one up the Nile and around the Red Sea, and a southern one across the narrow straight which, during the last ice age would have only been five kilometers across (Forster thinks the latter the most likely route). Between 60,000–30,000 years ago there was a great migration to Southeast Asia, Northern Asia, and Europe. Between 30,000–20,000 years ago, people spread throughout the rest of the world, including Australia, and between 20,000–15,000 years ago they migrated into North America, making their way into South America between 15,000–2,000 years ago. The final migration over the past 2,000 years saw the settlement of the Pacific islands.
The next lecture would have sent Darwinian fundamentalists into skeptical paroxysms, as Leticia Aviles, a zoologist at the University of British Columbia, summarized the evidence for “multilevel selection.” Darwinian fundamentalists (an intentionally pejorative term coined by Stephen Jay Gould) believe that the individual organism is the sole target of natural selection. Aviles said that below the individual, selection may occur at the level of genes, chromosomes, organelles, and cells. Above the individual, selection may occur at the level of social groups, demes, species, and multispecies communities. In that sense, Aviles said, “individual” depends on the frame of reference. She then applied multilevel selection to research on sex ratios, cooperation among non-relatives, and multicellularity. Social spiders are an example of group selection, Aviles continued. And sex ratios that depart from 1:1 cannot be accounted for by inbreeding alone, so group selection is here invoked. Likewise, the equilibrium of sex ratios is explained by both within-group selection and between-group selection. “When cooperation is not costly, groups, grouping, and cooperation evolve readily. But with increasing costs of cooperation, levels of cooperation decrease.”
The highlight of the second day was the lecture by the husband and wife team Peter and Rosemary Grant, both from Princeton University, made famous by Jonathan Weiner in his 1994 book The Beak of the Finch. Every year for the past three decades the Grants have parked themselves on Daphne Major, a tiny volcanic plug of an island 120 meters high and a kilometer long to study Darwin’s finches and the process of speciation.
Three million years ago an ancestral group of finches flew out to the Galapagos during a time of very active plate tectonics and the creation of the island archipelago. When this founder population arrived it encountered a very different environment from the one we see today: there were only five islands and the temperatures were much higher. Over the last three million years of fluctuations in global temperatures, there has been an overall net cooling of the islands. But when these little finches arrived 2.75 million years ago there was a permanent El Niño and the islands were warm and wet, during which there was an explosion of speciation. First came the warbler finch, then the tree finch (of which there are now five species) and then the ground finch (of which there are now six species). Following Ernst Mayr’s theory of allopatric speciation (where a founder daughter population breaks away from the parental population), the first finches landed on San Cristóbal, then migrated to Espanola, then to Floreana, then to Santa Cruz, and finally made their way back to San Cristóbal. Along the journey the finches adapted to local conditions. Finches in highlands developed larger beaks to break hard beetles and seeds. Finches in lowlands evolved smaller beaks for eating small seeds and succulents. As an opportunistic species, some of these finches also ate sea turtle eggs and sucked the blood from blue-footed boobies. Different adaptations to different islands lead to speciation.
The strongest environmental factor the Grants have observed is the rainfall pattern over 30 years on Daphne Major. Arriving in 1973, the Grants immediately witnessed a draught that wiped out 85 percent of the population of two species of finches (the ground finch Geospiza fortis and the cactus finch Geospiza scandens). From 1975 to 1978 there was almost no rainfall and natural selection operated rapidly to change beak size. In 1983, an El Nino rainfall produced an abundance of plants and trees and cactus fruit, all covered by vines. Two years after the El Nino event, the island dried out and the large seeds were replaced by small seeds, leading to a favoring of small pointy beaked birds. Beak shape, beak size, and body size all changed in parallel. The Grants summarized four lessons they learned about natural selection on Daphne:
1. It is an observable, measurable process in a natural environment.
2. It oscillated in direction.
3. It occurs when the environment changes.
4. It has evolutionary significance.
The Grants have made another important observation on a reproductive isolating mechanism in finches: song. Song is learned during a short sensitive period early in the life of a finch (between days 10 and 30), while still in the nest and being fed by their fathers. Only the males sing. A few learn variations on the song. Rosemary recounted an endearing story about a finch who got a cactus spine stuck in its throat that made its song more croaky; his sons subsequently learned the new croakier song, as did their sons, and so on through the generations, a clear example of a meme.
The Grants are heroes among evolutionary biologists, and their mere presence lifted the conference to a higher status, which was reciprocated the final day of the conference when they were awarded honorary doctorates from the Universidad San Francisco de Quito.
Day Three : Field Work
(photo of Post Office Bay:
Post Office Bay on the island of Floreana where, for centuries, sailors left mail to be picked up by ships going in the appropriate direction.)
The third day was allocated for field trips to locales I had previously visited, so I took the opportunity to SCUBA dive off Kicker Rock, a volcanic plug sticking straight out of the ocean that is choc-a-block full of marine organisms of numerous species and colors, and bisected by sharks swimming through a ten meter slit in the rock, making this one of the top choices of divers in the archipelago. I was certified to dive back in the Devonian (1972) but it had been an epoch since I last dove (1988) and at 60 feet down on the first dive I made the mistake of looking up — suddenly I had this crushing sense of anxiety, which subsided when I surfaced and descended slowly, staring at the wall and suppressing my vertical receptors. Darwin described and illustrated Kicker Rock, but until modern technology made it possible for humans to stay under water for extended periods, most evolutionary theory was based on surface-dwelling creatures.
I was slated as the keynote entertainment for Saturday night, and gave a lecture on Intelligent Design creationism. Since I certainly did not need to explain evolution to this eminent group, I focused instead on the IDers own works, beginning with their intellectual leader (these are slides from my Powerpoint presentation):
Baloney. (I used a stronger descriptor this evening.) The fact is that virtually all Intelligent Design creationists are Evangelical Christians who privately believe that ID and God are one and the same. There is nothing wrong with that, but if they would at least be honest about it I would respect them more. In point of fact, this is just a public façade constructed for public school consumption. In other venues they are forthright. For example:
Thus, in its relation to Christianity, intelligent design should be viewed as a ground-clearing operation that gets rid of the intellectual rubbish that for generations has kept Christianity from receiving serious consideration.
—William Dembski, “Intelligent Design’s Contribution to the Debate over Evolution: A Reply to Henry Morris,” 2005
The objective is to convince people that Darwinism is inherently atheistic, thus shifting the debate from creationism vs. evolution to the existence of God vs. the non-existence of God. From there people are introduced to ‘the truth’ of the Bible and then ‘the question of sin’ and finally ‘introduced to Jesus.’
—Rob Boston, “Missionary Man,” Church & State magazine, 1999, quoting Phillip Johnson
As I also demonstrated in my talk, IDers are disingenuous about their “science.” They are not doing science and they know it. To wit:
Because of ID’s outstanding success at gaining a cultural hearing, the scientific research part of ID is now lagging behind.
—William Dembski, “Research and Progress in Intelligent Design,” 2002 conference on Intelligent Design
We don’t have such a theory right now, and that’s a problem. Without a theory, it’s very hard to know where to direct your research focus. Right now, we’ve got a bag of powerful intuitions, and a handful of notions such as ‘irreducible complexity’ and ‘specified complexity’—but, as yet, no general theory of biological design.
—Dr. Paul Nelson, “The Measure of Design,” Touchstone magazine, 2004
To drive home the point, I show that even Christian biologists have no use for ID, as in this observation from Dr. Lee Anne Chaney, Professor of Biology at the Christian-based Whitworth College, from their house publication Whitworth Today, 1995:
As a Christian, part of my belief system is that God is ultimately responsible. But as a biologist, I need to look at the evidence. Scientifically speaking, I don’t think intelligent design is very helpful because it does not provide things that are refutable — there is no way in the world you can show it’s not true. Drawing inferences about the deity does not seem to me to be the function of science because it’s very subjective.
I then summarized the cognitive style of ID thusly:
1. X looks designed.
2. I can’t think of how X was designed naturally.
3. Therefore X was designed supernaturally.
This is the old “God of the Gaps” argument: wherever there is a gap in scientific knowledge, God is invoked as the causal agent. This is comparable to the “Plane problem” of Isaac Newton’s time: the planets all lie in a plane (the plane of the ecliptic). Newton found this arrangement to be so improbable that he invoked God as an explanation in Principia Mathematica: “This most beautiful system of the sun, planets, and comets could only proceed from the counsel and dominion of an intelligent and powerful Being.” Why don’t IDers use this argument any more? Because astronomers have filled that gap with a natural explanation.
I also summarized ID in practice thusly:
1. Scientists do not accept ID as science.
2. Therefore ID is not taught in public school science classes.
3. I think ID is science.
4. Therefore I will lobby the government to force teachers to teach ID as science.
This is what I call the “God of the Government” argument: if you can’t convince teachers to teach your idea based on its own merits, ask the government to force teachers to teach it. By analogy, in the early 1990s, I published a series of articles applying chaos and complexity theory to history. It is, of sorts, a theory of history, and I had high hopes that historians would adopt my theory, put it to practice, and perhaps even teach it to their students. They haven’t. Maybe I didn’t communicate my theory very clearly. Maybe my theory is wrong. Should I go to my congressman to complain? Should I lobby school board members to force history teachers to teach my theory of history? See how absurd this sounds? I particularly like this approach to ID because most IDers are Christians, most Christians are politically conservative, and most conservatives are in favor of small government. In fact, I close my lecture with an analogy between natural selection in nature and the invisible hand in the economy, where both produce design complexity without a top-down designer. Since most conservatives understand and support the workings of free markets, they should intuitively embrace the analogy.
(photo of Peter Grant and Daniel Dennett:
The World Summit on Evolution included a veritable Who’s Who of evolutionary theory, including, pictured here, Darwin finch expert Peter Grant (left) and philosopher and evolutionary theorist Daniel Dennett.)
Day Four : Setting the Agenda for the Next Decade]
The final day of the conference began with a completely unorthodox lecture by Cornell University evolutionary theorist William Provine. From the projection booth he provided periodic voice-over commentary on text slides we were supposed to read to ourselves (“I don’t read slides” he proclaimed), but for which he left on the screen for a few fleeting seconds inadequate for reading (and compounded with loud music that forced him to shout into the microphone). The gist of his talk was that we need a new theory of evolution, after which he listed 11 problems that included this statement:
Natural selection does not shape an adaptation or cause a gene to spread over a population or really do anything at all. It is instead the result of specific causes: hereditary changes, developmental causes, ecological causes, and demography. Natural Selection is the result of these causes, not a cause that is by itself. It is not a mechanism.
Provine’s White Whale is the theory of random genetic drift, and it tasks him. It is not random, he said.
The random assortment of chromosomes at meiosis is deterministic. What is the deterministic random number generator that produces random genetic drift? Random binomial sampling. Substitute inbreeding for random drift and then everything makes sense. Frequency of alleles at an individual locus drift, that is, they change in frequencies randomly. Linkage and recombination are ignored. Random drift is independent at each locus. When population size is small, the random drift is greater. Inbreeding and random drift are measured by the same variable, the inbreeding coefficient, F. Inbreeding increases frequency changes.
After providing numerous examples, Provine then concluded:
Random sampling from the allele pool doesn’t exist. The ‘gene pool’ is a bad term. There is no such thing as a gene pool for a population or species. Sewall Wright’s model requires each chromosome be cleaved at each locus each generation. This is a hopeless requirement. Random drift must be distinguished from inbreeding. Inbreeding effects stem from pairing chromosomes together with themselves, thus rendering them homozygous. Recessive traits are often revealed. Random drift must also be distinguished from founder effects. Founder effects lead to inbreeding effects, but not random drift because the new population is so small.
Since this is all beyond my pay scale, and since no one challenged him or even had a question in the discussion session, I privately canvassed the evolutionary theorists present for their opinion. With the exception of Lynn Margulis — who said she thinks that Provine is basically right even if he doesn’t communicate it clearly — no one else present thought that there was any merit to Provine’s challenges to modern evolutionary theory.
Next up was Niles Eldredge from the American Museum of Natural History who co-founded (with Stephen Jay Gould) the theory of punctuated equilibrium, which he nicely summarized in the first part of his talk that challenged Darwinian gradualism. But his primary focus was on Darwin, explaining that he practiced both Baconian induction and hypothetico-deduction. “At first Darwin was just collecting data, letting nature come to him, and then he formed hypotheses that could be tested.” From his reading of Darwin’s letters and notebooks, quotes from which he presented to the audience, Eldredge concluded that Darwin converted to evolution during the Beagle voyage. I asked Frank Sulloway about this later, and he said that this is absolutely false, adding that someone once asked Darwin if he became an evolutionist during his voyage, to which he unequivocally answered no.
University of Arizona evolutionary biologist Richard Michod delivered one of the finer lectures of the conference, clearly and succinctly outlining his research on Evolutionary Transitions in Individuality (ETIs). What is an individual?
In Latin it means indivisible; in philosophy it means distinct in space and time; in biology it means genetic homogeneity, genetic uniqueness, autonomy, and physiological unity.
Evolutionary individuals include genes, gene networks, prokaryote cells, eukaryotic cells, multicellular organisms, social groups, and mating pairs (sexual populations).
Evolution occurs not only through mutational change in populations but also during evolutionary transitions in individuality, when groups become so integrated that they evolve into new higher-level individuals.
Michod focused on two such ETIs: (1) asexual to sexual, (2) unicellular to multicellular. “Natural selection at any level requires heritable variation in fitness,” Michod explained.
Fitness has two basic components, fecundity and viability, and resources invested in one component often detract from the other, leading to trade-offs in fitness components. Fitness trade-offs gain special significance during ETIs. For example, in unicellular individuals, the same cell must contribute both fitness components; however, in multicellular groups, cells may specialize in one component or the other, leading to the specialization of reproductive and vegetative functions. As cells specialize, they relinquish their autonomy in favor of the group; as a result, fitness and individuality are transferred from the level of the cell to the level of the group.
Michod’s talk was the perfect lead-in for the penultimate lecture of the conference by the acknowledged star of the weekend, Lynn Margulis, famous for her pioneering research on symbiogenesis. Margulis began graciously by acknowledging the conference hosts and saying, “This is the most wonderful conference I’ve ever been to, and I’ve been to a lot of conferences.” She then got to work, pronouncing the death of neo-Darwinism. Echoing Darwin, she said “It was like confessing a murder when I discovered I was not a neo-Darwinist.” But, she quickly added, “I am definitely a Darwinist though. I think we are missing important information about the origins of variation. I differ from the neo-Darwinian bullies on this point.” She then outlined the basis of her theory of the origin of the cell nucleus as a fusion between archaebacteria (thermoplasma) and Eubacteria (Spirochaeta). “We live on a bacterial planet,” she reflected.
The cell is the fundamental unit of life. A minimal cell has DNA, mRNA, tRNA, rRNA, amino acylating enzymes, polymerases, sources of energy and electrons, lipoprotein membranes, and ion channels, all contained within a cell wall, and is an autopoietic (self-regulating feedback) system.
The biggest break in life, she explained, was between the prokaryotes (cells with nucleoids: monera, prokaryota; archaebacteria, eubacteria) and eukaryotes (cells with nuclei: protoctista, fungi, plantae, animalia).
In this framework, Margulis continued, all of life’s history can be divided into three major eons: Archean (3,500–2,500 million years ago), Proterozoic (2,500–540 Ma), and Phanerozoic (540–0 Ma). “Most evolutionary biologists deal with the Phanerozoic, which is like saying that history began in 1909 when the Ford Motor Company opened shop in Dearborn, MI,” Margulis quipped. The major steps in evolution involved symbiogenesis, which Margulis described succinctly as “the inheritance of acquired genomes” and more formally in its relationship to symbiosis, “the long-term physical association between members of different types (species).” The problem with neo-Darwinism, Margulis concluded, is that
Random changes in DNA alone do not lead to speciation. Symbiogenesis — the appearance of new behaviors, tissues, organs, organ systems, physiologies, or species as a result of symbiont interaction — is the major source of evolutionary novelty in eukaryotes — animals, plants, and fungi.
There were no direct challenges to Margulis in the discussion period that followed, so I once again queried a number of the experts in this area after the lecture. The overall impression I received was that Margulis goes too far in her rejection of neo-Darwinism, but because she was right about the role of symbiogenesis in the origin of the first eukaryote cells, they are taking a wait-and-see approach. One scientist added that since Margulis was to receive an honorary doctorate that afternoon, it seemed inappropriate to challenge her in this venue.
The final talk was delivered by evolutionary biologist Joan Roughgarden, from Stanford University. Evolutionary skepticism must have been in the air, for on the heals of Margulis’ pronouncement of the death of neo-Darwinism, Roughgarden proclaimed the death of Darwin’s theory of sexual selection. Darwin said that males have stronger passions than females, that females are coy, and that females choose mates who are more attractive, vigorous and well-armed. “People are surprised to learn how much sex animals have for purely social reasons (including same-sex sexuality in over 300 species of vertebrates),” Roughgarden explained,
and how many species have sex-role reversal in which the males are drab and the females are colorfully ornamented and compete for the attention of males, and that most plants and perhaps a quarter of all animal species have individuals that cannot be classified as male or female.
In response, University of Georgia evolutionary biologist Patricia Gowaty noted that Roughgarden is right in identifying the exceptions to Darwin’s theory and that there is much we still do not know, but added that since Darwin’s time much has been learned about mate selection and competition that should not be dismissed.
Conclusions
(photo of Frank Sulloway and William Schopf:
As an aside to the conference, UCLA paleobiologist William Schopf (left) assisted Frank Sulloway in photographing ecological changes in the Galapagos since Sulloway first visited the islands in 1968.)
In the end, what can be said about the state of evolutionary theory today? SUNY evolutionary biologist Douglas Futuyma, who wrote the book on evolution (literally — he is the author of the best selling textbook on evolution biology), opined after a particularly contentious exchange, “I am tempted to quote from Gilbert and Sullivan’s The Mikado: ‘I am right and you are right and all is right as right can be.’” Futuyma explained that he had agreements with everyone on some aspects of the various debates and controversies under discussion, but that in the end more research and more data will resolve some issues and open up new ones.
Herein lies science’s greatest strength: not only the ability to withstand such buffeting, but to actually grow from it. Creationists and other outsiders contend that science is a cozy and insular club in which meetings are held to enforce agreement with the party line, to circle the wagons against any and all would-be challengers, and to achieve consensus on the most contentious issues. This conclusion is so wrong that it cannot have been made by anyone who has ever attended a scientific conference. The World Summit on Evolution, like most scientific conferences, revealed a science rich in history and tradition, data and theory, as well as controversy and debate. From this I conclude that the theory of evolution has never been stronger.
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