Tag: human evolution

Why the evolution of humans was NOT inevitable; BioLogos peddles more dubious science

May 13, 2009 • 7:21 am

Over at that hilarious goldmine of accommodationism, Francis Collins’s BioLogos website (generously supported by The Templeton Foundation, they have posted an answer to the question, “Did evolution have to result in human beings?” Now if you know anything about this history of faith/science accommodationism, you know that the answer has to be “yes”, at least if you construe the question to mean “Did evolution have to result in a rational, highly intelligent being that was capable of apprehending and worshiping its creator?”  If God is running the evolutionary process, as the accommodationists maintain, then the evolution of humans (who are, after all, the goal of this process — the one species made in God’s image) could not have been left to chance.

And so, religious biologists like Kenneth Miller and Francis Collins, and “science-friendly” theologians like John Haught, have maintained in their writings that evolution would inevitably have coughed up an intelligent rational creature like Homo sapiens.  In other words, contrary to the assertions of Stephen Jay Gould, if we re-ran the tape of life, something humanlike would always appear.  Religious apologists always contend that the evolution of what we will call “humanoids” was not a continent process: it was built by God into the very fabric of evolution.

Of course, this is not a scientific belief.  For one thing, it makes humans different from other creatures.  The faithful don’t go around maintaining that the evolution of squirrels or cockroaches was an inevitable outcome of the evolutionary process, because according to Scripture God didn’t make rodents of insects in His image.  So God stuck his hand in, somewhere, to make humanoids appear.  That is creationism, pure and simple.  Or, he designed the process with the foreknowledge that humans would appear, which is also creationism, since no evolutionist really thinks that the process was jerry-rigged from the outset to produce certain life forms.

Second, if you do believe in a naturalistic and materialistic process of evolution in which God didn’t interfere, then the appearance of humans doesn’t seem likely at all — and certainly not inevitable.  Higher intelligence and rationality evolved only once, so it certainly isn’t something like eyes (whose morphology evolved independently dozens of time).  The idea that “convergent evolution” shows that humans were inevitable is deeply fallacious.

Yet BioLogos uses this argument — a favorite of the religious paleontologist Simon Conway Morris –to show that (surprise!) something like humans WAS inevitable in evolution.  After disposing of Gould’s contingency argument, they then approvingly reiterate Conway Morris’s “convergence” argument:

Humans: Inevitable, Intentional

Simon Conway Morris presents a different perspective, arguing humans, or a human-like species, are actually an inevitable part of evolution.  Morris is not proposing a different mechanism for human evolution, merely a different observation of its possible outcomes.  Morris would agree that any slight difference in the history of human DNA would result in a different evolutionary path.  Unlike Gould, however, Morris argues each of those possible pathways would inevitably lead to something like the human species.  Morris writes:

“The prevailing view of evolution is that life has no direction — no goals, no predictable outcomes. Hedged in by circumstances and coincidence, the course of life lurches from one point to another. It is pure chance that 3 billion years of evolution on Earth have produced a peculiarly clever ape. We may find distant echoes of our aptitude for tool making and language and our relentless curiosity in other animals, but intelligence like ours is very special. Right?”

“Wrong! The history of life on Earth appears impossibly complex and unpredictable, but take a closer look and you’ll find a deep structure. Physics and chemistry dictate that many things simply are not possible, and these constraints extend to biology. The solution to a particular biological problem can often only be handled in one of a few ways, which is why when you examine the tapestry of evolution you see the same patterns emerging over and over again.”

The patterns Morris mentions are also referred to as convergences in the evolutionary process.  In his most recent book, Life’s Solution, Morris gives many examples of physical traits or abilities found repeatedly among different species.5 Normally, such similarities are understood asthe result of common ancestry.  However, the species in Morris’s examples are known to be distantly related.  In many cases, not even these species’ common ancestor shared the same trait.  The implication is that several different species have independently developed similar traits.

The examples of convergence range across many levels of biology.  One popular and straightforward example is the human eye.  It turns out that several other species share a nearly identical visual system to that of the human eye, including the octopus.6 However, humans and octopuses have separate predecessors, neither of which shared this characteristic.  Two very different evolutionary paths arrived at the same visual system.  If Gould’s supposition is correct, and there was an infinity of other possible outcomes, then this example of convergence is all the more improbable.  Morris’s argument, conversely, is that the laws of nature allow for only a few solutions to any particular problem.  It appears the eye has developed independently at least seven times over the course of evolutionary time.

Human Significance

To see evidence for human significance, one need only consider Morris’s examples of convergence for many of the traits that are particularly relevant for human-like beings.  These examples include basic senses like balance, hearing and vision, as well as highly advanced features like the human brain.  Morris argues that evolution does not pose any threat to human significance.  Characteristics such as a large brain capable of consciousness, language and complex thought would inevitably have to emerge from the evolutionary process. Morris writes:

“Contrary to popular belief, the science of evolution does not belittle us.  As I argue, something like ourselves is an evolutionary inevitability, and our existence also reaffirms our one-ness with the rest of Creation.” 7

The exact anatomical features of this ultimate sentient being might not be precisely specified by the evolutionary process, however.  This thought can be unsettling to anyone who imagines our particular body plan is part of the imago Dei, or image of God. Despite the marvelous paintings in the Sistine Chapel, there is no reason to think that God the Father has a physical body that looks like ours.

God’s Sovereignty in the Evolution of Humans

Belief in a supernatural creator always leaves open the possibility that human beings are a fully-intended part of creation.  If the Creator chooses to interact with creation, he could very well influence the evolutionary process to ensure the arrival of his intended result.  (See Question 14 about Evolution and Divine Action.)  Furthermore, an omniscient creator could easily create the universe in such a way that physical and natural laws would result in human evolution.  (See Question 19 about Fine-Tuning of our Universe.)

Although the unpredictable mutations of DNA can make any species appear entirely accidental, Simon Conway Morris also puts forward strong arguments in favor of the inevitability of creatures that have the attributes of humans.  From this perspective, it seems the evolutionary process itself might be geared toward human life.

So it goes. (By the way, have a look at the last paragraph of this page where BioLogos suggests that the evolution of humanoids ON OTHER PLANETS was  improbable. (As expected, they take this stand because theologists can’t see God sending Jesus careening from planet to planet to save every species of alien).

The Argument for the Inevitability of Humanoids is perhaps the most popular argument (ranking with The Fine Tuning of Physical Constants) used by accommodists to show that evolution and God are not in conflict.  But the argument is simply wrong.  Nobody can say with assurance that the evolution of humanoids was inevitable.  The only honest response is “We don’t know” (and I would add “what we know about evolution tells us that it was probably not inevitable.”)

I attacked this argument in my New Republic essay “Seeing and Believing,” and for those who haven’t read it, or who don’t wish to plow through the link to find it, I’ll reproduce it here. This was a review of two books, Kenneth Miller’s Only a Theory: Evolution and the Battle for America’s Soul, and Karl Giberson’s Saving Darwin: How to be a Christian and Believe in Evolution.

III.

In Finding Darwin’s God, his earlier book, Miller proclaimed a universal theism: “Remember, once again, that people of faith believe their God is active in the present world, where He works in concert with the naturalism of physics and chemistry.” Giberson clearly agrees. And where do they find the hand of God in nature? Unsurprisingly, in the appearance of humans.

Giberson and Miller assert that the evolution of humans, or something very like them, was inevitable. Given the way that evolution works, they claim, it was certain that the animal kingdom would eventually work its way up to a species that was conscious, highly intelligent, and above all, capable of apprehending and worshipping its creator. This species did not have to look perfectly human, but it did have to have our refined mentality (call it “humanoid”). One of Miller’s chapters is even titled “The World That Knew We Were Coming.” Giberson notes that “capabilities like vision and intelligence are so valuable to organisms that many, if not most biologists believe they would probably arise under any normal evolutionary process…. So how can evolution be entirely random, if certain sophisticated end points are predictable?”

Reading this, many biologists will wonder how he can be so sure. After all, evolution is a contingent process. The way natural selection molds a species depends on unpredictable changes in climate, on random physical events such as meteor strikes or volcanic eruptions, on the occurrence of rare and random mutations, and on which species happen to be lucky enough to survive a mass extinction. If, for example, a large meteor had not struck Earth sixty-five million years ago, contributing to the extinction of the dinosaurs–and to the rise of the mammals they previously dominated–all mammals would probably still be small nocturnal insectivores, munching on crickets in the twilight.

Evolutionists long ago abandoned the notion that there is an inevitable evolutionary march toward greater complexity, a march that culminated in humans. Yes, the average complexity of all species has increased over the three-and-a-half billion years of evolution, but that is because life started out as a simple replicating molecule, and the only way to go from there is to become more complex. But now complexity is not always favored by natural selection. If you are a parasite, for instance, natural selection may make you less complex, because you can live off the exertions of another species. Tapeworms evolved from free-living worms, and during their evolution have lost their digestive system, their nervous system, and much of their reproductive apparatus. As I tell my students, they have become just absorptive bags of gonads, much like the students themselves. Yet tapeworms are superbly adapted for a parasitic way of life. It does not always pay to be smarter, either. For some years I had a pet skunk, who was lovable but dim. I mentioned this to my vet, who put me in my place: “Stupid? Hell, he’s perfectly adapted for being a skunk!” Intelligence comes with a cost: you need to produce and to carry that extra brain matter, and to crank up your metabolism to support it. And sometimes this cost exceeds the genetic payoff. A smarter skunk might not be a fitter skunk.

To support the inevitability of humans, Giberson and Miller invoke the notion of evolutionary convergence. This idea is simple: species often adapt to similar environments by independently evolving similar features. Ichthyosaurs (ancient marine reptiles), porpoises, and fish all evolved independently in the water, and through natural selection all three acquired fins and a similar streamlined shape. Complex “camera eyes” evolved in both vertebrates and squid. Arctic animals such as polar bears, arctic hares, and snowy owls either are white or turn white in the winter, hiding them from predators or prey. Perhaps the most astonishing example of convergence is the similarity between some species of marsupial mammals in Australia and unrelated placental mammals that live elsewhere. The marsupial flying phalanger looks and acts just like the flying squirrel of the New World. Marsupial moles, with their reduced eyes and big burrowing claws, are dead ringers for our placental moles. Until its extinction in 1936, the remarkable thylacine, or Tasmanian wolf, looked and hunted like a placental wolf.

Convergence tells us something deep about evolution. There must be preexisting “niches,” or ways of life, that call up similar evolutionary changes in unrelated species that adapt to them. That is, starting with different ancestors and fuelled by different mutations, natural selection can nonetheless mold bodies in very similar ways–so long as those changes improve survival and reproduction. There were niches in the sea for fish-eating mammals and reptiles, so porpoises and ichthyosaurs became streamlined. Animals in the Arctic improve their survival if they are white in the winter. And there must obviously be a niche for a small omnivorous mammal that glides from tree to tree. Convergence is one of the most impressive features of evolution, and it is common: there are hundreds of cases.

All it takes to argue for the inevitability of humanoids, then, is to claim that there was a “humanoid niche”–a way of life that required high intelligence and sophisticated self-consciousness–and that this niche remained unfilled until inevitably invaded by human ancestors. But was its occupation really inevitable? Miller is confident that it was:

“But as life re-explored adaptive space, could we be certain that our niche would not be occupied? I would argue that we could be almost certain that it would be–that eventually evolution would produce an intelligent, self-aware, reflective creature endowed with a nervous system large enough to solve the very same questions we have, and capable of discovering the very process that produced it, the process of evolution…. Everything we know about evolution suggests that it could, sooner or later, get to that niche.”

Miller and Giberson are forced to this view for a simple reason. If we cannot prove that humanoid evolution was inevitable, then the reconciliation of evolution and Christianity collapses. For if we really were the special object of God’s creation, our evolution could not have been left to chance. (It may not be irrelevant that although the Catholic Church accepts most of Darwinism, it makes an official exception for the evolution of Homo sapiens, whose soul is said to have been created by God and inserted at some point into the human lineage.)

The difficulty is that most scientists do not share Miller’s certainty. This is because evolution is not a repeatable experiment. We cannot replay the tape of life over and over to see if higher consciousness always crops up. In fact, there are good reasons for thinking that the evolution of humanoids was not only not inevitable, but was a priori improbable. Although convergences are striking features of evolution, there are at least as many failures of convergence. These failures are less striking because they involve species that are missing. Consider Australia again. Many types of mammals that evolved elsewhere have no equivalents among marsupials. There is no marsupial counterpart to a bat (that is, a flying mammal), or to giraffes and elephants (large mammals with long necks or noses that can browse on the leaves of trees). Most tellingly, Australia evolved no counterpart to primates, or any creature with primate-like intelligence. In fact, Australia has many unfilled niches–and hence many unfulfilled convergences, including that prized “humanoid” niche. If high intelligence was such a predictable result of evolution, why did it not evolve in Australia? Why did it arise only once, in Africa?

This raises another question. We recognize convergences because unrelated species evolve similar traits. In other words, the traits appear in more than one species. But sophisticated, self-aware intelligence is a singleton: it evolved just once, in a human ancestor. (Octopi and dolphins are also smart, but they do not have the stuff to reflect on their origins.) In contrast, eyes have evolved independently forty times, and white color in Arctic animals appeared several times. It is hard to make a convincing case for the evolutionary inevitability of a feature that arose only once. The elephant’s trunk, a complex and sophisticated adaptation (it has over forty thousand muscles!), is also an evolutionary singleton. Yet you do not hear scientists arguing that evolution would inevitably fill the “elephant niche.” Giberson and Miller proclaim the inevitability of humanoids for one reason only: Christianity demands it.

Finally, it is abundantly clear that the evolution of human intelligence was a contingent event: contingent on the drying out of the African forest and the development of grasslands, which enabled apes to leave the trees and walk on two legs. Indeed, to maintain that the evolution of humans was inevitable, you must also maintain that the evolution of apes was inevitable, that the evolution of primates was inevitable, that the rise of mammals was inevitable, and so on back through dozens of ancestors, all of whose appearances must be seen as inevitable. This produces a regress of increasing unlikelihood. In the end, the question of whether human-like creatures were inevitable can be answered only by admitting that we do not know–and adding that most scientific evidence suggests that they were not. Any other answer involves either wishful thinking or theology.

Miller opts for theology. Although his new book does not say how God ensured the arrival of Homo sapiens, Miller was more explicit in Finding Darwin’s God. There he suggested that the indeterminacy of quantum mechanics allows God to intervene at the level of atoms, influencing events on a larger scale:

“The indeterminate nature of quantum events would allow a clever and subtle God to influence events in ways that are profound, but scientifically undetectable to us. Those events could include the appearance of mutations, the activation of individual neurons in the brain, and even the survival of individual cells and organisms affected by the chance processes of radioactive decay.”

In other words, God is a Mover of Electrons, deliberately keeping his incursions into nature so subtle that they’re invisible. It is baffling that Miller, who comes up with the most technically astute arguments against irreducible complexity, can in the end wind up touting God’s micro-editing of DNA. This argument is in fact identical to that of Michael Behe, the ID advocate against whom Miller testified in the Harrisburg trial. It is another God-of-the-gaps argument, except that this time the gaps are tiny.

Obviously, given that higher intelligence and rationality of the human type has evolved only once, the existence of convergence says nothing about whether these features would always appear.  In fact, the one-offness seems to imply otherwise.

What bothers me about this is, of course, that BioLogos is using the imprimatur of science (and the wonky ideas of Simon Conway Morris) to try to convince people that of course our evolution was inevitable.  This tactic is a favorite of BioLogos (and Templeton), for it tries to blur the boundaries between science and faith.  As scientists we can say nothing about the inevitability of humans except that it seems unlikely given its unique appearance.  Certainly one can say that the idea of evolutionary convergence is irrelevant here.

Please, BioLogos, stop making scientific arguments for God!

Hobbits are back, and they’re REAL!

May 7, 2009 • 1:11 pm

I’ve written quite a bit about the Homo floresiensis controversy: these are the small (1-meter tall) individuals whose remains were found in a cave on the Indonesian island of Flores, originally dated about 18,000 years old.  They are remarkable because of their size, their small brains (about the size of a chimp’s) and their remarkably recent age — a time when the much taller and brainier Homo sapiens had already infested the world.  But there was doubt about whether these diminuitive fossils represented a real species: some people thought that the one relatively complete skull represented a diseased or microcephalic individual.

Two papers in the latest issue of Nature (links below) address this controversy, and both come down on the side of H. floresiensis being a real species, not an aberration. (There’s also a very nice two-page summary by Daniel Lieberman if you don’t want to plow through the articles.)  More bones have been found in the Liang Bua cave on Flores (see below), most notably a pretty complete foot.  The foot, like the rest of the skeleton, shows an intriguing mixture of primitive and derived traits.  There are now enough bones to pretty much rule out the “aberrant individual” theory.

So what was H. floresiensis?  As the diagram below shows, it could have been a descendant of an earlier hominin species, H. habilis, or perhaps a very early form of H. erectus; in both cases it would have had to reach the island several million years ago.  Yet the brains of these two ancestors were larger than that of the hobbit, so how did it get such a small titer of gray matter? (Hobbit brains were about 400 cc in volume, the size of a modern chimp or of the smallest australopithecines.)  Here the notable dwarfism of many species on islands (including elephants on Flores) comes in: like other mammal species, H. floresiensis could simply be an evolutionarily dwarfed form of an earlier hominin. Weston and Lister’s paper gives relevant data taken, oddly enough, from dwarf hippos on Madagascar , but I’ll leave you to follow their reasoning in their article.

This is perhaps the most bizarre and interesting twist in hominin evolution yet, and it’s completely unsettled.  A whole new group of questions open up.   How did this weird species coexist with the much larger and brainier H. sapiens for so long?  (H. floresiensis was not dumb, by the way: they managed to colonize the island over water and made fairly sophisticated tools).  If hobbits are a remnant of the H. habilis lineage, how come we don’t find habilis fossils elsewhere outside of Africa?

The foot of Homo floresiensis.   W. L. Jungers, W. E. H. Harcourt-Smith, R. E. Wunderlich, M. W. Tocheri, S. G. Larson, T. Sutikna, Rhokus Awe Due & M. J. Morwood

Insular dwarfism in hippos and a model for brain size reduction in Homo floresiensis. E. M. Weston and A. M. Lister

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Ling Bua cave on Flores: where the hobbits were found.  Photograph by C. Turney, University of Wollongong

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Homo floresiensis might be most closely related to early H. erectus, but also shows potential affinities with H. habilis. In either case, recognizing H. floresiensis as a species will require us to re-examine how we define species of the genus Homo and how they were related to each other. Reasonably well-known relationships are indicated by solid arrows; less secure relationships are indicated by dotted arrows. Broken vertical bars indicate uncertainties about when species evolved or went extinct. (Figure and caption from Lieberman’s summary.)

What early Europeans might have looked like

May 5, 2009 • 7:01 am

Today’s Daily Mail reports on an upcoming BBC2 program in which a forensic scientist Richard Neve, using 40,000-year-old bones, recreated the face of a very early inhabitant of Europe.  This was soon after “modern Homo sapiens” began migrating out of Africa and populatint the world (ca. 100,000 to 60,000 years ago).

From the article:

To sculpt the head, Mr Neave called on his years of experience recreating the appearance of murder victims as well as using careful measurements of bone.

It was made for the BBC2 series The Incredible Human Journey. This will follow the evolution of humans from the cradle of Africa to the waves of migrations that saw Homo sapiens colonise the globe.

The head has taken pride of place on the desk of Alice Roberts, an anthropologist at Bristol University, who presents the programme.

‘It’s really quite bizarre,’ she told Radio Times. ‘I’m a scientist and objective but I look at that face and think “Gosh, I’m looking at the face of somebody from 40,000 years ago” and there’s something weirdly moving about that.

‘Richard creates skulls of much more recent humans and he’s used to looking at differences between populations.

‘He said the skull doesn’t look European or Asian or African. It looks like a mixture of all of them.

‘That’s probably what you’d expect of someone among the earliest populations to come to Europe.’

And, if you’re of European ancestry, no matter how far back, here’s what your forebear might have looked like:

early-european

Who is the type specimen of Homo sapiens?

March 20, 2009 • 12:43 pm

by Greg Mayer

The answer is: Carl Linnaeus, the great Swedish naturalist. But there’s a story behind this bare fact.

One of the great problems facing natural history in the 18th century was the problem of diversity: the great variety of plants and animals from all over the world that began flooding into European museums as the result of voyages of exploration. Although it was not until Darwin’s idea of descent with modification that a fully satisfactory solution to the problem began to come within reach, Linnaeus made a signal contribution by establishing a nomenclature– a system of names– by which this diversity could be ordered, and with which it was possible to discuss the problem.  The principles of the system have undergone considerable development since then, but the 10th edition of Linnaeus’ Systema Naturae remains the starting point of zoological nomenclature.

One of the post-Linnaean developments is that all species should have a type specimen. A type specimen is not, as the name might seem to imply, a typical (in the sense of normal or average) member of a species.  Rather it is a specimen that fixes the application of a name to a particular zoological species.  Thus, I know that the name Anolis roosevelti applies to the large, arboreal (and now, unfortunately, apparently extinct) anole lizard of the islands east of Puerto Rico, because I can go the Museum of Comparative Zoology and examine the type specimen that is kept and carefully preserved there, and see that this specimen is indeed a member of that species.  Having the application of a name fixed is most important when it turns out that more than one species is masquerading under one name.  My friend and colleague Richard Thomas of the University of Puerto Rico, for example, discovered that Eleutherodactylus portoricensis, one of the most beloved frogs of Puerto Rico, actually consisted of two species, one of which had previously gone unrecognized.  The type specimen of E. portoricensis belonged to one of these two species, so it, of course, retained the name portoricensis; the newly recognized one was actually the more common and widespread of the two, and he gave it the name  Eleutherodactylus coqui, after its vernacular name, coqui, which was given in imitation of its nocturnally ubiquitous call.

All of this is by way of introduction to the issue at hand: who is the type specimen of Homo sapiens? In last week’s issue of Nature, Andrew Hendry of the Redpath Museum says

curiously, humans have never had a designated type specimen, despite attempts by American palaeontologist Edward Drinker Cope to have himself so designated

Is this so? No. In 1959, W.T. Stearn, in an article (Systematic Zoology 8:4-22) commemorating the 200th anniversary of the 10th edition of the Systema Naturae, wrote

Since for nomenclatorial purposes the specimen most carefully studied and recorded by the author is to be accepted as the type [specimen], clearly Linnaeus himself, who was much addicted to autobiography, must stand as the type of his Homo sapiens!

While there is a certain tongue-in-cheek quality to this, it satisfies the criteria of the Code of Zoological nomenclature, and thus Stearn has designated Linnaeus as the type specimen of Homo sapiens (Linnaeus, in naming Homo sapiens, had not designated a type specimen, which in his day was not customarily done).

So, as noted at the start, we do have a type specimen, Carl himself.  Did the great paleontologist Edward Drinker Cope ever try to have himself made the type specimen of Homo sapiens? Again, no.  Although Cope did leave his body for study, and there may be an oral tradition at the Academy of Natural Sciences that he wanted to be the type, there’s no written evidence he did. Earle Spamer, now of the American Philosophical Society, wrote a detailed article (Proceedings of the Academy of Natural Sciences of Philadelphia 149:109-114) exploring this claim. The written claim arises in a popular book by Louie Psihoyos and John Knoebber called Hunting Dinosaurs, with a foreword by famed paleontologist Bob Bakker. In the book, the authors relate how in about 1993 they borrowed Cope’s skull, and traveled around with it, showing it to paleontologists.  Bakker, according to the story, told them that man had no type specimen, and since Cope wanted to be it, they set about making it so.  But even if Bakker was unaware of Stearn’s designation decades earlier, the details of the story are all wrong.  Bakker would have known that a type designation does not require the description and measurements pictured and described in the book, that the type specimen must be chosen from among specimens examined by the original author (in this case Linnaeus in 1758, 82 years before Cope’s birth), and that there is no official “review board” to which such designations are submitted (the International Commission on Zoological Nomenclature can be appealed to in order to set aside the rules, but they don’t review actions that follow the rules).  In the foreword, Bakker himself makes no mention of ever having tried to actually make Cope the type specimen. No publication by Bakker claiming to make Cope the type has ever appeared, and Psihoyos and Knoebber’s journalistic account of Bakker’s supposed but unfulfilled intention to do so does not itself constitute a published nomenclatural act under the Code of Zoological Nomenclature.

It’s hard to tell how much Bakker might have been pulling Psihoyos’ and Knoebber’s legs, or just playing along, or if the authors just misinterpreted a lot of what Bakker said and did. Spamer seems to take this all a bit too seriously, and may err in ascribing much of it to Bakker, who did not actually author any part of the book but the foreword. But Carl Linnaeus is the type specimen of Homo sapiens; and Edward Drinker Cope has never been put forward for the job, and, without special action by the International Commission, he wouldn’t even qualify for it.

(Note by JAC:    Thanks to Dr. David Hillis of the University of Texas at Austin, who helped clarify this situation.)

Update: I’ve just come across a newspaper article that says that Bakker did publish a designation of Cope as the type specimen in 1994 in the Journal of the Wyoming Geological Society. The author of the newspaper article, Scott LaFee, did speak to some knowledgable people, including Ted Daeschler and Gary Rosenberg of the Academy of Natural Sciences. The article doesn’t note, though, that Cope is barred from being the type specimen because he wasn’t among the specimens seen by Linnaeus, and that Stearn’s designation (although mentioned by LaFee) preempts any later designation by Bakker. LaFee also seems to think a type specimen must be “typical” in the sense of average, which, as noted in the original post, it needn’t be.  I’m going to try to track down Bakker’s paper, and will post my findings here.

Update 2: I’d posted the update right after finding the mention of the article in the  Journal of the Wyoming Geological Society, because I thought it would take me a while to get a copy of the right issue of an obscure journal, and I wanted to immediately correct my claim that Bakker never published. Well, it turns out I was right in the first place. There is apparently no such journal.  There isn’t even a Wyoming Geological Society (there is a Wyoming Geological Association). I’m not sure where the claim originates: I’ve not found a mention of the fictional journal in Psihoyos’s book. It seems to me that some deliberate joking has gone on here. I’ll also mention here that I’ve seen some web commentary to the effect that Stearn’s designation doesn’t count, because “nobody can agree“.  This is incorrect: nomenclatural actions that follow the rules are valid, regardless of whether or not others think it was a good action to take.

Neanderthals and sex

March 9, 2009 • 12:10 am

by Greg Mayer

A couple of news items from the past month deserve a quick comment or two. First, at the American Association for the Advancement of Science annual meeting in Chicago last month, Svante Paabo of the Max Planck Institute announced the completion of a draft genome for Neanderthal man, and that it indicated that modern man and Neanderthal man did not interbreed: the Neanderthals are our evolutionary cousins, not members of our own species.  The work by Paabo on the Neanderthal genome, and on ancient DNA in general, is fabulous, but two caveats must be noted: the first draft covers only 63% of the genome; and, most of the DNA comes from one cave in Croatia. So what you can say is in the 63% of the DNA they’ve looked at there’s no sign of interbreeding at this location. But we know secondary contact of differentiated populations in ice age Europe can be very complex; e.g. hooded crows would show evidence of interbreeding with carrion crows if sampled in some places but not others, so the case isn’t closed. And a personal quibble: according to the BBC

The draft genome can give us clues to the genetic regions which make us “uniquely human”, Prof Paabo told BBC News.

Besides the usual need to realize that knowing the genome of “X” doesn’t mean we know what it is that makes “X” so “X-ian”, Paabo implies here that Neanderthals weren’t human.  But by any biologically coherent notion of human they were (hence Homo neanderthalensis). John Hawks (hat tip: Pharyngula) has an excellent discussion of all sorts of issues relating to the Neanderthal genome.

Second, John Long (who has a wonderful book on fish evolution) and two colleagues published a paper in Nature (abstract only) reporting internal fertilization and vivipary in a placoderm, a group of ancient fish. This is a wonderful discovery, showing again that Philip Skell doesn’t know what he’s talking about (Skell, you’ll recall, had said fossils “cannot reveal the details that made these amazing living organisms function”!!!). But the paper got twisted in media reports into these fish inventing sex.  The BBC headline said “Fish fossil clue to origin of sex“, while, even more inexcusably, the British Museum (Natural History) website had “Fish knew first about sex“. Sexual reproduction originated in bacteria, probably billions of years before these fish. These fish may be the earliest vertebrates with copulation with an intromittent organ (a penis or similar structure); such organs have evolved multiple times, including four times in the amniotes (reptiles, birds, mammals).  The price of journalism is eternal vigilance.

Homo footprints from Kenya

February 27, 2009 • 10:00 am

by Greg Mayer

In today’s issue of Science, Matthew Bennett and eleven colleagues from Britain, America, Kenya and South Africa report on the discovery of ancient footprints:

Here, we report hominin footprints in two sedimentary layers dated at 1.51 to 1.53 million years ago (Ma) at Ileret, Kenya, providing the oldest evidence of an essentially modern human–like foot anatomy, … The Ileret prints show that by 1.5 Ma, hominins had evolved an essentially modern human foot function and style of bipedal locomotion.

Although there were no directly associated fossils, the most likely maker of the prints was Homo erectus.  In WEIT, Jerry discussed the famous 3.75 million year old Laetoli, Tanzania footprints, which established that our ancestors had walked bipedally since at least that time.  The Laetoli prints, however were made by Australopithecus afarensis, and the newly announced prints are the oldest known for our genus, Homo (we are Homo sapiens), and Bennett et al. discuss the ways in which the Ileret prints indicate their makers had a more modern foot morphology than the makers of the Laetoli prints.  Homo erectus had a smaller brain than we do, so we see a general pattern in the fossil record exemplified: mosaic evolution–  different characters evolving at different rates.  In this instance, we see an essentially modern foot, with a brain that is intermediate between Australopithecus and modern Homo.  And, we see, once again, that intermediate forms occur at the times, and in the places, we expect them to on the hypothesis of descent with modification.

Update: A reader asks are the new prints from Homo erectus or Homo ergaster, two very closely related fossil species of Homo.  Bennett et al. don’t claim one or the other, writing:

The large stature and mass estimates derived from the Ileret prints compare well with those of Homo ergaster/erectus on the basis of postcranial remains and are significantly larger than postcrania-based stature and mass estimates for Paranthropus boisei and Homo habilis (table S3) (19–21), suggesting that the prints at FwJj14E were made by Homo ergaster/erectus individuals.

In media reports, other scientists, for example Daniel Lieberman of Harvard (quoted in the New York Times), have referred to the prints as from erectus.  My own view is that the species taxonomy of fossil hominids is probably oversplit; if there is to be one name, it would, by priority, be erectus. The great Ernst Mayr wrote a paper in 1951 entitled ‘Taxonomic categories in fossil hominids’ (Cold Spring Harbor Symposia on Quantitative Biology 15:109-118), and it’s worth rereading; see also what Jerry had to say in chapter 8 of WEIT.

Is “The Hobbit” a fraud?

February 1, 2009 • 10:50 am

As recounted in WEIT, one of the most remarkable hominin fossils is that of Homo floresiensis, discovered on the island of Flores in Indonesia in 2003. This creature was remarkable in that although it lived only 18,000 years ago, when modern H. sapiens had already evolved, it was only a meter tall, weighed 50 pounds, and had a brain of less than 500 cc.–similar in size to of our distant cousin Australopithecus afarensis (“Lucy”). It seemed that some relict populations of Homo had survived on this Indonesian island, bypassed by modern humans.

Ever since H. floresiensis (dubbed “The Hobbit”) was found, it has been the center of heated controversy. Some have said that rather than being a long-surviving ancient hominin, for example, the one good specimen found is simply that of a modern human afflicted with a growth disease (such as goiterious cretinism) that produced a small skull. Others counter-claim that the wrist bones of the hobbit are clearly not that of a modern human, but of an earlier relative.

Now another criticism has surfaced–the claim that the hobbit’s teeth show dental work! In particular, an anthropologist at the University of Adelaide in Australia, Maciej Henneberg, claims that a lower molar of H. floresiensis shows a filling (and possibly a root canal) of the type performed in Indonesia in the 1930s. (See the articles about this claim here and here.) Could the hobbit be another Piltdown Man, a fraud foisted on a credulous scientific community?

Well, probably not. In a careful analysis of the dentition of H. floresiensis and a comparison with other ancient skulls, Peter Brown, one of the hobbit’s discoverers, debunks Henneberg’s claims. X rays and careful analysis (see the pictures on Brown’s page) show absolutely no evidence of dental work. Thus this claim, at least, has been debunked.

It is starting to look as if H. floresiensis really was a genuine species, but an anomalous one: a small population of tiny humans who hunted dwarf elephants with miniature spears. There will undoubtedly be more argument before this is settled.

flores_sapiens

H. floresiensis (l.), H. sapiens (r.). Photograph courtesy of National Geographic news.