Interview with Jerry in American Scientist

March 5, 2009 • 8:36 am

by Greg Mayer

An interview with Jerry on evolution vs. creationism appears in the online pages of American Scientist. In the interview, Jerry talks mostly about his approach to teaching evolution based on 25 years experience, and how he applied that experience in the writing of WEIT. A couple of highlights:

…when you read Darwin, the thing that’s most fascinating is the evidence he musters in support of it. In talking with professional biologists and evolutionists, they didn’t ever learn why people thought evolution was true, because you’re not taught that in class. But I thought that that should be passed on to the students because of the second reason I wrote the book, which is the pervasiveness of creationism in this country. I wanted to educate the students so they know that evolution really happened, so they don’t really doubt that, but also to arm them against the forces of irrationality that were going to be impinging on them and society….

And so when I teach the stuff I teach it as sort of an object lesson in how to adjudicate between competing theories in science. And that’s the way I wrote the book, too. I’m constantly asking the reader, “How does creationism explain this observation? It can’t.” So it’s more than teaching the evidence; it’s teaching them how to discriminate between good science and bad science, and that’s a good lesson for students too.

Stephen Jay Gould and the origin of jaws

March 4, 2009 • 5:34 pm

by Greg Mayer

There’s been some interesting discussion in the comments on the post on Change we can believe in concerning gradual and punctuational evolution, including the question of whether Stephen Jay Gould ever advocated macromutation. (Among his many accomplishments, Gould joined Niles Eldredge in the explication and elaboration of Eldredge’s initial suggestion of the idea of punctuated equilibria.) Over a very productive 30+ year career, Gould’s views were of course not static, but in a 1980 paper (Is a new and general theory of evolution emerging? Paleobiology 6:119-130) he does advocate macromutation:

Instead, I envisage a potential saltational origin for the essential features of key adaptations. Why may we not imagine that gill arch bones of an ancestral agnathan moved forward in one step to surround the mouth and form proto-jaws?

Gould refers here to the serial homology of vertebrate jaws to the gill skeleton, the discovery of which is one of the triumphs of classic comparative anatomy. He proposes jaws to have arisen from the gill skeleton in a single mutation (i.e. a macromutation). There is always the problem that what’s a big mutation to one person is not big to another, but I think most or all vertebrate morphologists would consider the conversion of a gill arch into a jaw in one step a macromutation. In context, Gould is not arguing that all the features of jawed vertebrates would have arisen at once, but that a very major feature would have. Two arches are involved in the jaws: the mandibular arch, forming the jaws themselves, and the hyoid arch, which supports and suspends the mandibular.  Since there are extinct fishes (the acanthodians) whose hyoid arch is little modified from a gill arch, both of the arches involved in jaws did not change in one step. The exact way in which jaws arose is not known, and is the subject of continuing  anatomical, developmental, molecular genetic, and paleontological research.  New fossils from the Chengjiang Lagerstatte in China are beginning to throw more light on early vertebrate evolution, but are a bit early for the origin of jaws; we may hope, and predict, that further discoveries will shed more light on the origin of jaws.

Sympathy for the human: further consideration of my cat Peyton

March 3, 2009 • 11:39 am

by Greg Mayer

I gave a public lecture yesterday at my university entitled “Is There a Moral Instinct?”  Part of what I did was to elaborate on the theme of Steve Pinker’s rudimentary moral sentiments– sympathy, trust, retribution, gratitude, guilt– and how I see them exemplified in the behavior of my cat, Peyton.  I showed some video of Peyton-human interactions, including the following, showing trust. She’s exposing her belly and throat for scratching in a way that makes her vulnerable, and thus trust must accompany the seeking of tactile pleasure.

In this next video she’s playing with me, and in doing so holding back from scratching and biting strongly. She wasn’t really very interested in playing at the time, and I had to initiate it, but note that she does not leave, which she easily could do. As I described in a previous post, when her sympathy and trust are removed, she’s quite capable of inflicting painful wounds. The gentle bites and scratches of play are not due to some inability of the cat to fight effectively with people, but rather are an action that mitigates harm to another– sympathy.

Feathered dinosaurs

March 2, 2009 • 10:01 pm

by Greg Mayer

One of the most exciting developments in paleontology in the past ten years or so has been the discovery that many species of theropod dinosaurs had feathers.  The earliest discoveries were quite controversial.  At the 1997 meetings of the Society of Vertebrate Paleontology in Chicago, a paper was read criticizing the interpretation of the skin structures on these fossils as feathers. In response, Phil Currie, one of the team working on the fossils,  presented an impromptu rebuttal paper later the same day, a rather unusual development for a normally tightly scheduled scientific meeting.  I was not convinced they were feathers myself until a while later, when a number of fossils of the new forms were brought to the Field Museum, and I was able to see them for myself– they had feathers!  One of the strangest of these feathered dinosaurs was Microraptor gui, which had both its forelimbs and hindlimbs modified into feathered wings.  It seems to exemplify the remark of J.B.S Haldane, the British geneticist who was one of the founders of the modern synthesis, “that the universe is not only queerer than we suppose, but queerer than we can suppose.”  Jerry highlights Microraptor in chap. 2 of WEIT, and notes a NOVA program on PBS, “The Four-winged Dinosaur”, that has a great website with interactives and videos, including the entire program. Originally airing last year, it was just recently shown again on my local PBS station, so check to see if it may be showing again in your area too.

Most of the specimens of feathered dinosaurs, as well as many true birds, have come from the fossil beds of Liaoning in northeastern China. The American Museum of Natural History has a nice website on the Liaoning fossil biota.  The Liaoning deposits have become one of the most important and interesting of what are called Lagerstatten (singular: Lagerstatte), a German word for a fossil deposit with extraordinary conditions of preservation. Such deposits, because they reveal structures (such as soft parts like feathers) and organisms (those lacking hard parts) otherwise missing from the fossil record, are often of crucial importance in studying the history of life on Earth.  Other famous Lagerstatten include the Pre-Cambrian Ediacara Hills of Australia, the Cambrian Burgess Shale in British Columbia and Chengjiang in China, and the Jurassic Solnhofen Limestone of Bavaria. These Lagerstatten have revealed, respectively, an early multicellular fauna, the Cambrian Explosion, including the earliest vertebrates, and Archaepoteryx, the first bird.

Change we can believe in

March 1, 2009 • 11:13 am

by Greg Mayer

The now iconic images of President Obama created by Shepard Fairey last year have been widely imitated. It was perhaps inevitable that Darwin should be included among those so honored.Darwin in Obama-style poster

Created by Mike Rosulek, he is selling t-shirts and posters of this, and several other designs, with proceeds to benefit the National Center for Science Education, a most worthy recipient.  I might quibble with “very gradual”, which might evoke memories of the old punctuated equilibrium debate.  Darwin was certainly a gradualist, but as understood by Darwin, and succunctly characterized in chapter 1 of WEIT, gradualism is not incompatible with highly varying rates of change across time and among lineages.  The best summary of Darwin’s views on the subject is a paper by Frank Rhodes entitled ‘Gradualism, punctuated equilibrium and the Origin of Species‘ published in Nature (305:269-272) in 1983.

(hat tip: Andrew Sullivan)

Caturday felid

February 28, 2009 • 7:09 am

by Greg Mayer

Oscar the cat gained fame in 2007 when David Dosa reported in the New England Journal of Medicine that he had “an uncanny ability to predict when residents [of the nursing home where he lives] are about to die.”

Oscar the cat becomes death
Oscar the cat

Dosa continues

Thus far, he has presided over the deaths of more than 25 residents on the third floor of Steere House Nursing and Rehabilitation Center in Providence, Rhode Island. His mere presence at the bedside is viewed by physicians and nursing home staff as an almost absolute indicator of impending death, allowing staff members to adequately notify families. Oscar has also provided companionship to those who would otherwise have died alone. For his work, he is highly regarded by the physicians and staff at Steere House and by the families of the residents whom he serves.

An article in Slate later urged us, wisely in my opinion, to take Dosa’s article, if not Oscar, with a grain of salt. Oscar is shown here with the physicist J. Robert Oppenheimer ‘s famous rendering of a line from the Bhagavad Gita; Oppenheimer may be seen saying it in this video.

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.

More good books

February 26, 2009 • 7:57 am

by Greg Mayer

In an earlier post, Jerry called Janet Browne’s two-volume work the best of Darwin biographies, calling it “magisterial and engagingly written.”  I concur, and some of our readers have mentioned it approvingly in the comments.  But, at 1200 + pages, it may be a bit daunting as a starting place.  Let me offer two other starting places for the Darwin enthusiast.  Charles Darwin, by Tim BerraThe first is Charles Darwin: The Concise Story of an Extraordinary Man, by Tim Berra, an ichthyologist from Ohio State.  In this slim (144 pp.), well illustrated, volume Berra covers most of the highlights of Darwin’s life, work, and death, and includes a handy annotated list of Darwin’s books and chronology of his life.  There is a nice section of color plates (many by Berra himself of the Galapagos and Down House, Darwin’s home), including my favorite, a painting of 32 breeds of domestic pigeon, one of Darwin’s favored study animals. An afternoon’s read, it is a good place to start.

For a broader view of the science of evolution, but, like WEIT, aimed firmly at the general reader, I highly recommend The Discovery of Evolution, The Discovery of Evolution, by David Youngby David Young of the University of Melbourne. Richly illustrated with both color and line art from contemporary scientific publications, and covering a broad sweep of history, from John Ray and Francis Willughby in the 17th century through to the Modern Synthesis, with a quick tour of more recent developments, it is one of the finest books I’ve ever read not just on the history of the field, but on evolutionary biology itself.  It achieves this distinction by introducing and explicating, in chronological sequence, not just the ideas and historical figures, but the evidence on which the major discoveries of evolutionary biology are based.  It is refreshing and, indeed, exciting, to have these discoveries and attendant scientific debates addressed through the evidence adduced by the discoverers and debaters.  Thus, for example, the phenomenon of natural extinction,  which we today take for granted, is presented as the lively debate it was at the time, and we see it is resolved not by some textbook fiat (as too much of science education seems to be), but by careful anatomical, biogeographic, and geological research, with the great Georges Cuvier’s work on elephants, mammoths, and mastodons playing a major part in the resolution.  The entire book is replete with such examples, and is itself an edifying model of how science should be taught and learned: by direct consideration of the evidence.