Book Month continues...

Why Evolution Is True - Jerry Coyne

I already mentioned one of the three great books about evolution that came out recently: Your Inner Fish, by Neil Shubin*. I heartily recommend pairing Fish with WEIT, as they have some overlap in content and style. This is an easily-accessible review of the most important (and compelling) bits that pile up in support of the idea that evolution has occurred over time, and that natural selection is its principle driver. It's full of interesting facts that are clear refutations of the idea of divine creation of all species from separate starting points in the recent geological past. FYI, Coyne is also a blogger: he writes semi-daily at the blog Why Evolution Is True (shocking title, eh?).

The Greatest Show on Earth - Richard Dawkins

Richard Dawkins gets plenty of press time for his athiest viewpoint, and he's written a book about that, too (which I haven't read). As a result, many theists probably won't want to touch any of his other tomes with a ten-foot pole. But I assure you, that would be a huge mistake when it comes to The Greatest Show on Earth: this is an amazing, rich, awesome book. It demolishes the notion of a young Earth and special creation with a treasure trove of information about biological systems. More importantly, it celebrates the beauty of evolution: Dawkin's delight in the various evolved solutions to the problems of living is evident. Like luciferin, it shines from the page. The way I see it, Why Evolution Is True and Your Inner Fish play the part of "executive summaries," while The Greatest Show on Earth is the juicy, complicated, tangled jungle of evolutionary explanation. It's great. While it lacks the quality of being concise, Dawkins' erudition and clear-mindedness more than make up for it. Consider Coyne's WEIT as your appetizer, but save Dawkins for the main course.
____________________________________________

Labels: books, evolution

In the new issue of Scientific American, vodcast host and prodigious author Steve Mirsky takes on James Inhofe and Ray Comfort. No news here if you're the sort of person who follows climate politics and creationism shenanigans, but his short essay is pretty funny.

Labels: climate change, evolution, global warming, humor, podcasts and vodcasts, politics

Last new year's, I stated some of my goals for the year. Here they are again; I'll bold the ones I actually accomplished, and strike through the ones that I didn't.

1. visiting the Galapagos Islands
2. visiting the high Andes (Cotopaxi, Chimborazo), Ecuador
3. finding a cool outcrop of graded beds in the Martinsburg Formation (late Ordovician turbidites in the Shenandoah Valley of Virginia) that Rick Diecchio told me about last week
4. "walking on the Moho" in Gros Morne National Park, Newfoundland (late summer)
5. seeing Snowball rocks and Ediacarans on the Avalon Peninsula, Newfoundland (late summer)
6. visiting Egg Mountain paleontological site, Montana
7. joining my colleague Ken Rasmussen's field trip to the Culpeper Basin, a Triassic rift valley in northern Virginia
8. some cool trip next winter break (2009-10): perhaps Patagonia? Or Antarctica?

I've also got some big teaching resolutions:

1. Running a successful and robust Structural Geology course for George Mason University (spring semester).
2. Running a successful and innovation Environmental Geology course for NOVA (spring semester).
3. Running a successful and safe Regional Field Geology of the Northern Rocky Mountains course for NOVA (summer semester).
4. Preparing and running a successful and groundbreaking Honors Historical Geology course linked with English Literature 242 at NOVA, where the English professor and I will bridge the two subjects with readings of Lyell, Darwin, "A Pair of Blue Eyes," and others (fall semester). (didn't get sufficient enrollment for this one; bummer!)

On other topics:

1. Finish my M.S.S.E. degree (July)
2. Buy a house
3. Put together a series of geology 'vodcasts' on local geology (though I've gathered a lot of footage that will eventually go into this series)
4. Write a few freelance articles [link]
5. Publish one cartoon per month in EARTH
6. Prepping (cutting and polishing) a backlog of rock samples from all over the place (I'll have to share the story soon of how our "Campus Safety Officer" emasculated my rock saw out of a fear of accidents and ensuing litigation: it's an absolute abomination...)
7. Successfully moving the geology department into our new building

So what's up for the coming year, 2010?

1. More structure at GMU! Bigger, better, tweaked towards greater learning.
2. Hire and train a new member of the NOVA geology team to take on some of the tasks that my colleagues and I can't currently keep up with.
3. Actually get up to Newfoundland this year. I've got a family reunion up there in early August, so hopefully that will be the catalyst. (My mom's side of the family are Newfies.)
4. Run my Rockies course (with co-instructor Pete Berquist) again.
5. Update my website's numerous mentions of "greywacke" (English spelling) to "graywacke" (American spelling).
6. Get my geoblogging under control. I'm clearly devoting too much time to this for too little recompense. Maybe an alternate would be: find a grant or some such to fund the time I spend writing this blog.
7. Continue my cartooning for EARTH. Also occasional freelance writing pieces.
8. Scan my Cartoon Guide to Geology and post it for download/printing on Lulu.
9. Take meaningful action as a "citizen scientist" to combat climate change misinformation, creationism and Intelligent Design mumbo-jumbo, and other forms of pseudoscience pertinent to my expertise as a geologist.
10. Get those geology vodcasts going.
11. Go to Antarctica. (fingers crossed)
12. Work less. Relax more. Be creative. Enjoy life.

Labels: antarctica, canada, climate change, evolution, montana, newfoundland, pseudoscience, structure, teaching

The Way Things Break has a nice "review" post up pointing to the "emerging scientific consensus on the SwiftHack e-mails."

I hope my e-mails never get published online because I can sometimes be brusque or snarky or dimwitted and ignorant, and this incident has reminded me never to type something online that I don't mind the whole world seeing. A good thing to be reminded of, particularly (listen up, young people) in terms of the sorts of stuff that gets press time on Facebook.

That being said, I think it was wise of (CRU head) Phil Jones to step aside for an inquiry. My sense of things so far is that there isn't anything wrong, but I'm willing to be convinced otherwise if the inquiry suggests there was any kind of fraud. The e-mails I've seen are not particularly damning scientifically, given that they are taken out of context. All data gets processed, and I suspect that's all that was going on at CRU, though the words used to describe it are unfortunate. A lot of scientists I know write e-mails the way I do, and I'm sure it would be easy to take any particular e-mail completely out of context and interpret it incorrectly and embarrassingly.

I wonder what life would be like for other scientists if they were working on politically-charged topics like climate change. What would the structural geologists say if a tectonics working group got hacked and a media firestorm erupted with individuals quoting a line or two of an e-mail out of context to suggest that plate tectonics was a vast conspiracy of left-winger outdoorsy types just looking for research dollars so they could go hang out in the mountains? Or a group of sedimentologists get hacked, and the hackers scream that their e-mails show geologic time is a fraud? Maybe some physicists could get hacked, and the resulting headlines on Fox News would be that "Theory of Gravity called Into Question. Inquiry Launched." Chemists: it could happen to you too. You won't be able to keep your "everything is made out of atoms" charade up much longer...

One more, for reals: I wouldn't be the least bit surprised if there were some creationists out there looking at this chaos and thinking, "We should hack some biologists' e-mails, and then publish the lines that would call evolution into question." Stay tuned for that. You heard it here first.

I want to be excited for Copenhagen, but this CRU "Climategate" business definitely casts a shadow over things. Unfortunate timing...

Labels: climate change, evolution, geologic time, global warming, humor, politics, science and society

Incredible camoflauge. Via Skepchick.

Labels: evolution, reptiles

Last night, four Honors students and I (and Lily) went to the meeting of the Paleontological Society of Washington for Richard Bambach's talk on Charles Darwin's geological perspective.

One thing I liked about the talk was the suggestion by Darwin that "The tree of life should perhaps be called the coral of life, base of branches dead; so that passages cannot be seen." (Notebook B, page 25). This strikes me as quite apt: trees are alive not only at the tips of their branches, but also all along the branches, down to the trunk and the roots. Corals, on the other hand, grow atop a pile of dead material, representing those individuals and species which are in the past. I like it.

PS - While I was Googling up the exact quote, I came across this intriguing looking article about the history of the "tree of life" analogy. Wish I had time to read it...

Labels: analogies, corals, evolution, meetings

Heh! I love it.

Labels: art, blogs, evolution, history, humor, websites

Upcoming Paleontological Society of Washington meeting:

Darwin's Geological Perspective and the Origin of The Origin of Species

Richard Bambach
Professor Emeritus of Paleontology, Virginia Tech
Research Associate, Department of Paleobiology,
Smithsonian Institution, National Museum of Natural History

Wednesday, Nov. 18, 2009
7:00 p.m., in the Cooper Room, National Museum of Natural History
10th St. & Constitution Ave.
Non-Smithsonian visitors will be escorted
to the Cooper Room at 6:30 and 6:55 p.m.
Meet in the Constitution Avenue lobby at 5:00 p.m. to join us for dinner at "Elephant and Castle." Latecomers can meet directly at the restaurant at the NW corner of 12th & Penn. Ave., NW

In honor of the 150^th anniversary of the publication of Origin of Species (published November 24, 1859), Bambach will talk about how Charles Darwin's geological experience especially his following Lyell's approach to geology, influenced his early development of his theory of descent with variation. Bambach got interested in Darwin's geological connections when he realized that the only professional title Darwin ever used in publications was "Secretary to the Geological Society". While Darwin's geological work has recently been well studied (an excellent book by Sandra Herbert, Charles Darwin, Geologist was published by Cornell Univ. Press in 2005) the connections between Darwin's geological perspective and his early work developing his theory in the late 1830s and early 1840s have not been directly publicized yet by anyone. Geologists and paleontologists can take pride in the roll geology played in Darwin's development of his ideas.

Bambach is Professor Emeritus of Paleontology at Virginia Tech and is currently a Research Associate in the Department of Paleobiology, Smithsonian Institution, National Museum of Natural History and also an Associate of the Harvard Herbaria, Harvard University. He has a B. A. in biological sciences from Johns Hopkins and a Ph. D. from Yale in geology. He has been awarded the R. C. Moore Medal (for Excellence in Paleontology) by the Society for Sedimentary Geology (SEPM) and the Paleontological Society Medal from the Paleontological Society.

Labels: evolution, geology, meetings, psw

So that's how it works... (from the Onion.)

Labels: birdies, evolution, humor

Richard Dawkins is on a speaking tour in promotion of his new book on the evidence for evolution, which I just got yesterday. He's not coming to DC, but the closest speeches he'll be giving are in Charlottesville, at UVA (Oct.16), and then in Philadelphia, at the library (Oct.22).

Labels: evolution, meetings, pennsylvania, virginia

Awesome: right-handed Anomalocarids!
Elizabeth Kolbert on getting things moving re: climate policy.
The volcanological blogs are all agog over tephra and teeth.
Lockwood tears into sloppy "press release" style "journalism."

Labels: blogs, climate change, evolution, politics, science and society

Somehow, I've gotten a lot of reading done over the past six months. A lot of this reading consisted of books on climate change -- more on that in another post. But I wanted to share my thoughts on a few other books:

Sand - Michael Welland [blog]

Awesome. The perfect little book for those interested in geology. Looking at the world through a grain of sand. Very diverse, chock full of fascinating stuff that appeals to the intellect on many levels. Smart, erudite, funny. Recommended.

Stories In Stone - David Williams [blog]

A good read; like reading a compliation of feature stories in EARTH magazine; however, unlike Sand, no single unifying theme ties them all together. The overall idea is that the rocks we make our buildings out of have interesting backstories. The book is organized into a dozen or so chapters, each about a different building stone. Some are common (Indiana limestone), some are rare (petrified wood). All have got interesting stuff going on in terms of their geological history, human tie-ins, and architectural tweaks. If you live or work in a building, it's worth reading.

Your Inner Fish - Neil Shubin

Superb. Learned a ton about evolution's lingering fingerprints on our bodily blueprint. Did you know that the nerve which controls our larynx runs from the brain to the larynx via the heart? This unintelligent design is a vestige of the way our body develops from an embryo -- and can be traced directly to fish. There wasn't as much about Tiktaalik in here as I expected, but just enough to make the point.

Bones, Rocks, and Stars - Chris Turney [blog]

Really interesting, though the chapter on King Arthur didn't do much for me. But the rest of it is a great introduction to the various ways we figure out how old things are (Subtitle: "The Science of When Things Happened"). Great chapters on the orbital forcing of ice ages, carbon dating of Homo florensis (which Turney did), and Pleistocene megafauna extinctions. Recommended.

Glacial Lake Missoula - David Alt

Not so great as a book. Really more of a field guide, but not even all that great on that level. It essentially traces the geologic evidence of GLM "and its humongous floods" from Missoula north, west, south, and west again -- the path of the big Channeled Scablands-forming megafloods. A good resource for specific outcrops that illustrate parts of our understanding of this huge event, but not especially enjoyable to read.

Bretz's Flood - John Soennichsen

Much better -- a lovely biography of J. Harlan Bretz, the geologist from the University of Chicago who first documented the Channeled Scablands and deduced that they must have been carved by an enormous flood. A perfect little portrait of an academic's career. Bretz appears to have been quite a character! I really enjoyed the perspective this gave me on the whole "megaflood" idea.

Labels: books, evolution, floods, geologic time, sediment

The Smithsonian's National Museum of Natural History is looking for a creative individual to work on contract in the capacity of Producer/Writer for a new Human Evolution website. In this capacity, the individual will work with the Museum's Human Evolution Web team, and coordinate with the Web Development Contractor to bring creative solutions to presenting the human evolution story, shaping, editing, and writing multimedia content. We are looking for someone with experience writing science stories, producing multimedia, and developing content for museums. For more information, contact Robert Costello, costellor@si.edu.

Labels: anthropology, evolution, jobs, museums, smithsonian

Working through my RSS feed from the past week when I was out of town: Sheesh, it sure builds up if you don't stay on top of it! A couple of notable items to share:

The geography of tapirs, from the Why Evolution Is True blog.

The declining emphasis on literacy in our society, from Alternet.

Women geoscientists who read and/or write blogs: complete this survey!, from Kim.

Outcropedia, a new web project to catalog and share key outcrops.

Climate change graph jam, from Tamino. (With follow-ups from Lockwood)

Skeptics & athiests visit the Creation Museum. (ABC News)

Labels: blogs, evolution, graphics, humor, maps, politics, websites

Labels: art, evolution, nova, teaching

WTF? Really?

Labels: evolution, primates, science and society

Elizabeth Kolbert writes about topics I'm interested in reading. I dig her.

The latest is a piece she wrote in last week's New Yorker entitled "The Sixth Extinction?"

It's about the decline in biodiversity around the world, using frogs succumbing to a deadly fungus and white-nose syndrome in bats as case studies in extinction. It has a decent (though not perfect) geologic perspective -- worth reading. The online version is hidden behind a paywall, but maybe you can access it at your local library.

Labels: amphibians, evolution, geologic time, mammals

I've gotten hooked on watching these TED talks. You should too.

Here's Peter Ward talking about mass extinctions. I like this because I saw Ward give a similar talk at NSF once, and meant to blog about it, but got distracted by a thousand other things, and now here it is, a year later, and I can finally showcase this talented scientist discussing his specialty:

It gets a little fringey towards the end with talk about battle wounds and preserving people, but I like scientists like Ward who think outside the box and connect up different perpectives and different fields of inquiry. Enjoy!

Labels: evolution, fossils

I'm sure I won't be the only one to be writing about this today, but here's a couple of links to news items about Liberty University's "Advanced Creation Studies" students touring the Smithsonian Institution's National Museum of Natural History.

NBC (snarky!)
Washington Post (with photos)

Labels: evolution, museums, news, smithsonian, teaching

Brilliant! Especially in light of the new fossil evidence about the origins of whales released earlier this year.

From last week's issue of the New Yorker, which I've got time to read today because it's a snow day here in DC!

Labels: art, evolution, fish, fossils, humor, mammals

National Geographic has a gallery of seven "missing link" species whose fossils have been discovered since Darwin proposed the origin of new species by means of natural selection. It troubled Darwin that the fossil record didn't show more explicitly the transitions between species, but he proposed his hypothesis anyhow. Good hypotheses make testable predictions, and this is a nice example of how the ensuing 150 years of paleontology have validated the notion of species' change through time.

Labels: art, evolution

Heh! A gem from Mr. Hrynyshyn.

Labels: blogs, evolution, grants, teaching

Forbes.com has a suite of evolution-related and Darwin-related articles online at their website, in case you're looking for something to do. A diverse suite of topics, including examinations of Alfred Russel Wallace, the evolution of the brain, the intelligent design debate, and the relationship of evolutionary principles to economics, literature, and love.

Hat tip to Cathy B. for the link!

Labels: evolution

As noted everywhere, next Thursday is the 200th anniversary of Charles Darwin's birth. We've got fun plans at NOVA (and you're invited), but you might also opt for this symposium at the National Museum of Natural History downtown:

Thursday, February 12, 2009
Darwin Anniversary Symposium
Baird Auditorium, 12:00 noon to 3:00 pm

February 12, 2009 marks the 200th birthday of Charles Darwin and the 150th year since the publication of his influential work, On the Origin of Species. To recognize Darwin's scientific accomplishments, including his observations on plant and animal life, the National Human Genome Research Institute at the National Institutes of Health, in conjunction with the Smithsonian National Museum of Natural History, offers a day of discussions with distinguished panelists that will focus on a variety of topics from historical perspectives of Darwin to evolution and medicine.

Labels: evolution, meetings, smithsonian

No need to hear me say it... Get it straight from the source:

Library of Congress Hosts Lecture By Sandra Herbert, Feb. 18

The Science, Technology and Business Division of the Library of Congress will celebrate the 200th anniversary of Charles Darwin's birth with a lecture by Sandra Herbert, one of the world’s leading authorities on Darwin. She will discuss her book Charles Darwin, Geologist, which explores how geology changed Darwin and how Darwin changed science.

Herbert will lecture at 11:30 a.m. on Wednesday, Feb. 18, in the Pickford Theater on the third floor of the James Madison Building, 101 Independence Ave. S.E., Washington, D.C. A book-signing will follow the lecture, and the science reference staff will display Darwin items from the Library's collections. The event is free and open to the public; tickets or reservations are not needed.

In "Charles Darwin, Geologist," Herbert provides a fresh perspective on the life and accomplishments of Darwin, who was born on Feb. 12, 1809 (the same day as Abraham Lincoln) and whose thoughts and theories about the natural world hold true today - 150 years after the publication of his "On the Origins of Species by Means of Natural Selection" (London, J. Murray, 1859).

While Darwin is best known for his voyage on the HMS Beagle, his study of finches on the Galapagos, and his theory of evolution, he had wider interests in the field of science, including geology. According to Herbert, "In the 19th century, geology attracted persons of imagination, like Darwin, because of its promise of knowledge of the distant past." Herbert shows how Darwin's study of geology and his developing ideas about geological systems profoundly shaped his creative insight and scientific methods as he worked toward an understanding of evolution and natural selection.

Charles Darwin, Geologist, written largely at the Library of Congress, won the Geological Society of America's Mary C. Rabbitt Award, the American Historical Association's George L. Mosse Prize and the History of Science Society's Levinson Prize for Historical Work in the Life Sciences as well as the Albion Book Prize given by the North American Conference on British Studies.

Herbert recently retired as director of the program "the Human Context of Science and Technology" and professor of history at the University of Maryland, Baltimore County. She is also editor of the Red Notebook of Charles Darwin (1979) and Charles Darwin's Notebooks, 1836-1844: Geology, Transmutation of Species, Metaphysical Enquiries (1987).

As a Distinguished Visiting Scholar for 2006-2007 at Christ's College in Cambridge, Herbert assisted the university with its plans to celebrate Darwin's bicentennial. Herbert first saw the Charles Darwin Archives at Christ College when she was a graduate student at Brandeis University. The archives contain Darwin's notebooks, papers and correspondence, and when she discovered the material she remembers thinking "It was like finding out Shakespeare had left unpublished plays behind."

The Library of Congress maintains one of the largest and most diverse collections of scientific and technical information in the world. The Science, Technology and Business Division provides reference and bibliographic services and develops the general collections of the Library in all areas of science, technology, business and economics, with the exception of clinical medicine and technical agriculture, which are the subject specialties of the National Library of Medicine and the National Agricultural Library. For more information, visit http://www.loc.gov/rr/scitech.

Labels: evolution, history, meetings

As promised, here's some details for the event I mentioned the other day:

2:15- 4:45 Lisa Williams: Various displays of models, samples, artifacts, posters.
2:15 - 2:25 Bill Stanclift: Piano
2:25 -2:30 Reva Savkar : welcome and introduction of first speaker
2:30 - 2:45 Ralph Eckerlin: "Review of Darwin's life and accomplishments"
2:50- 3:10 Tom Macke: "Lincoln"
3:15 - 3:30 Karla Henthorn: "Common Misconceptions About Darwin"
3:35- 3:50 Jill Caporale: "The poetry in Darwin"
3:55 - 4:05 Nan Peck: "fun Lincoln-Darwin game"
4:10- 4:25 Bill Gorham: "Thomas Henry Huxley: Bulldog"
4:30 - 4:45 Callan Bentley: "Charles Darwin, Geologist"

200th Birth Anniversary of Lincoln and Darwin Celebration: The event will be held in the Ernst Community Cultural Center Forum on the Annandale campus of NOVA, Feb 12, 2009, starting at 2:15pm.

Labels: evolution, history, meetings, nova

My clever & creative colleague Reva Savkar (chemistry) is putting together a celebration of the 200th birthday of two important individuals in the history of the world: Abraham Lincoln and Charles Darwin, both born on February 12, 1809. The event will be held in the Ernst Community Cultural Center Forum on the Annandale campus, starting at 2:15pm.

The details are still being organized, but the event will feature short talks, music, and activities both from NOVA faculty and outside guests. Confirmed so far are: Bill Stanclift, Reva Savkar, Ralph Eckerlin, Tom Macke, Karla Henthorn, Jill Caporale, Nan Peck, and Bill Gorham.

I'll be presenting a 15-minute talk, starting at 4:30pm entitled "Charles Darwin, Geologist."

The event is free & open to the public. Join us!

Labels: evolution, geology, history, meetings, nova

Jesse Carlucci of the Diagenesis blog has an excellent piece up today about the term "Darwinism" and its pitfalls on many levels. You should go check it out immediately.

Labels: blogs, evolution, words

Chemists at Scripps have created an indefinitely-self-replicating molecular system, based on the "RNA World" hypothesis for the origins of life. Read all about it at the Royal Society of Chemistry website.

Labels: chemistry, evolution, news, origins of life

Chris Nedin alerted me (via his excellent Ediacaran blog) about this video (which was in turn posted at Larry Moran's The Sandwalk blog). I found it worth watching, though the language change partway through (from the third-person to the second-person) gives it an accusatory feel. In spite of that, this is probably worth viewing for introductory science students to distinguish what they hear labelled as "science" in general society from what a scientist considers "science." It's 10 minutes long, but in many places cleverly illustrated:

Labels: blogs, evolution, pseudoscience, science and society

Just wanted to let readers know that my "mineral evolution" cartoon is now up at the EARTH magazine website, accompanying their article on the new study by Bob Hazen about how the planet's suite of minerals has (a) changed over time and (b) been influenced by biologic processes.

Labels: art, evolution, humor, minerals

At work last week, I gave a bunch of exams. Historical Geology took their midterm, and both classes (Historical + Physical) took their lab practical exams. One of the essay questions on the Historical Geology midterm was about evolution. I specifically asked "what is the logic behind and evidence for Charles Darwin's theory of evolution by natural selection?" And while some of the responses I got where excellent (and some were lousy), a large number used the phrase "survival of the fittest," which I never use when explaining evolution. My reasoning for avoiding it is that is an oversimiplification, and not a full explanation. It's almost always more complicated than that.

Curious about whether it was explicitly used in the textbook, I skimmed through the chapter dealing with evolution, and found one instance where it said "... surival of the more fit." But that's not what the students were saying, and tellingly, the ones who used it were not using the phrase as part of a larger, lucid explanation of natural selection's workings. It was more of a placeholder for an actual explanation.

I think where they're getting it is pre-existing ideas about evolution, unrelated to the content I provide in this course of study. It's a phrase, a simplistic platitude, that's already in their heads when they sign up for my course, and I'm failing them by failing to discover it and then debunk it when we cover that topic.

I followed up a bit on that and did a count. 12 students did not use the phrase "survival of the fittest" in their essays, with an average score of 3.29 out of 5 possible points. Eight students did use the phrase in their essays, with an average score of 2.75 out of 5 possible. This is interesting to me: those students that used the cliche' "survival of the fittest" did WORSE than the students who didn't use it. There were four tests that scored a perfect 5/5, and none of them used "survival of the fittest." Of the four students who scored 4/5 (the next highest score), three didn't use the phrase, and one did. Interesting, eh?

I think this is exactly what the PBS program A Private Universe and ensuing series Minds of Our Own were getting at. (I blogged about them here.) It's all about identifying students' misconceptions, and then working to disassemble those misconceptions, and show students how the misconceptions are wrong or incomplete, and THEN building up new knowledge. This "survival of the fittest" business has convinced me it's very important to probe for students' pre-existing ideas before I teach a lesson.

Thoughts?

Labels: evolution, teaching

Today, I'm honored to present my first NOVA Geoblog guest post. After listening to my talk "Rise of the Geoblogosphere" at the Geological Society of Washington in September, E-an Zen (former president of the Geological Society of America, member of the National Academy of Sciences) approached me with some concerns about the nature of blogs as a vehicle for communicating science. I encouraged him to put his thoughts together, and that I would publish the resulting manuscript here as a guest post. Collaborating with Allison "Pete" Palmer, Dr. Zen provided me yesterday with the post you find below. Enjoy reading it, and please enter your comments below. --CB

WHAT IS "THE SCIENTIFIC METHOD"?
DISTINGUISHING VALID SCIENCE FROM PSEUDO-SCIENCE

E-an Zen and Allison R. Palmer
October 25, 2008

Debates about the nature of science and of science education are being actively carried out in our society, apparently reflecting a real need for improved understanding of what is at stake. On one side of the conversation are those who consider that science and "scientific research" represent efforts to rationally comprehend the physical aspects of the universe; in this process of understanding, the supernatural can play no part. Many advocates of this "rational" perspective consider their efforts to transcend cultural and institutional boundaries of human institutions.

There are others in our society, however, who point out that there are different ways of "knowing", and question whether the "rational" approach is adequate as a way to comprehend the universe. Particularly active against this "rational" model are some who consider the world we live in, and the life forms it carries, as creations of a transcendental being (some people of Abrahamic faiths might identify this being as the personal God). Among these advocates are some who deny the fundamental proposition that scientific investigation must exclude the "supernatural" because the latter is beyond rational and observation-based understanding. They point out that this exclusion is based on a particular model of knowing, and they challenge its validity in a real, rather than a model, world. Some Christians who belong to this group regard the Bible as literally inerrant and in situations of conflict the Bible trumps science-based inferences; others avoid the explicit invocation of a Christian God, yet claim that the world's life forms include products of direct and specific creative intervention of a super being (see Miller, 2008 for a thorough and informative exploration of this issue).

These apparently incompatible perspectives have generated passionate public concern because the public policy derivatives of the discussion include science education in public schools. Some who accept a role for the supernatural also promote the concepts of Young Earth Creationism and of Intelligent Design. Thus we must ask: under what circumstances could these be regarded as valid alternatives to observation-based science, acceptable not only for discussion among intellectually mature citizens, but suitable for pre-college science education? The debates, unfortunately, have devolved into legal contests resulting in judicial rulings which can make it difficult to carry out rational debate of the merits of the issues. Any educational value in a classroom setting with well-informed teachers is thereby forfeited.

The advent of the blogosphere has changed the landscape of this discourse: advocates on both sides can now broadcast, with limitless distribution, their arguments in cyberspace as "information" with neither peer review nor intellectual constraint. Blogs can be accessed directly by school-age readers, and the legal barriers about what may be taught in science classrooms cannot be enforced. There is no institution for prior review or vetting of mis-information about science by school boards, teachers, or parents.

How should the community deal with this challenge? Can we establish some consensus about what should be off-limits in blogs directed to school-age students, while keeping due respect for the sanctity of diversity of views about our world and its origins? How could we ensure that the students will be able to use the blogosphere for better understanding of the "scientific method of inquiry"?

We claim that "academic freedom" is not an adequate excuse for free-wheeling teaching in a science class. In a science class, the first order of business should not be to pass down masses of data and "facts", but to tell the students what doing or thinking about science amounts to. The core of scientific inquiry is its open-ended nature: We let the evidence lead us to the appropriate inferences, rather than use science as a tool to justify a predetermined conclusion. Scientific investigation never ends, because the answer to one question invariably leads to the next, deeper question of "why", "how", "when", or "where".

Let us describe our notion of the "scientific method" of inquiry, even as we recognize that this is not the only method for asking questions about our universe. We can do no better than quote Karl Popper. In his essay "Science: conjectures and refutations" (1963, p. 47-48 in the 2002 reprinted edition), Popper made the following (excerpted) sequential points:

"(1) It is easy to obtain confirmations, or verifications, for nearly every
theory - if we look for confirmations. (2) Confirmations should count only
if they are the result of risky predictions ... (3) Every "good" scientific
theory is a prohibition: it prohibits certain things to happen ... (4) A theory
that is not refutable by any conceivable event is non-scientific.
Irrefutability is not a virtue of a theory (as people often think) but a
vice. (5) Every genuine test of a theory is an attempt to falsify it, or
to refute it. ... (6) Confirming evidence should not count except when it is the
result of a genuine [italics his] test of the theory; and this means that it can
be presented as a serious but unsuccessful attempt to falsify the theory."

Popper concluded that "One can sum up all this by saying that the criterion of the scientific status of a theory is its falsifiability*, or refutability, or testability."

* Popper used "falsify", "refute", and "test" as interchangeable synonyms. This is unfortunate because in common parlance "falsify" means to commit a fraud, to cheat, or to alter the record deliberately for nefarious purposes. The word "to falsify" should be avoided in the discussion of the scientific method (unless we want to say "to cheat"); instead, use either "refute" or "invalidate."

Popper went on to this bold, but important conclusion (2002, p. 61):

"This was a theory of trial and error - of conjectures and refutations... I
thought ... that scientific theories were not the digest of observations, but
that they were inventions - conjectures boldly put forward for trial, to be
eliminated if they clashed with observations; with observations which were
rarely accidental but as a rule undertaken with the definite intention of
testing a theory by obtaining, if possible, a decisive refutation."

It goes without saying that the initial conjecture must be triggered by some observations; It is not something pulled out of thin air.

The stories of Creation, in the version advanced by the Young Earth Creationists, or even by those who advocate Intelligent Design for the "irreducibly complex" apparatus of life organisms (see Dembski, 1999; Behe, 2008) are, by contrast, show-stoppers, because there is no way to apply to supernatural processes the method of scientific testing.

The process of invalidation, or refutation, of a scientific conjecture is a public process; it is open to everybody. The process includes peer review, formal or informal, of the reasoning as well as the conclusions. The scientific explanations, "theories" if you will, are forever on probation. There are varying degrees of certainty, but that certainty is never absolute and the most venerable hypothesis or theory may be demolished by a single "decisive refutation." The process of inquiry represented by invalidation never ends; Doing science requires a deep sense of humility and readiness to admit mistakes.

Those of us who subscribe to the Popperian method of scientific inquiry, however, could and should do a lot better when we communicate with our friends who admit a role for supernaturalism in science. We suggest that in debating this issue, we should:

1. Show respect for those who disagree. Do not condescend: many of those who disagree are highly trained, very bright people. Our differences are one of philosophy, not intelligence!
2. Seek to build dialogues that could enhance mutual understanding and mutual trust. That need includes a shared awareness of "trojan horses" that could sneak into a conversation. We need to be not just open, but honorable; We must understand that others may distrust us as much as we do them, often, alas, for good reasons!
3. Be careful in the use of words. Words may have connotation that are objectionable to others, or that can confuse an issue through misunderstanding. We already mentioned "falsify" as an example. "Theory" is another one; Even "creation" has conflicted meanings. Each of us can think of additional examples. Let our discussions not run aground on such silly shoals!
4. Emphasize that in teaching about science, the exploration of the METHOD OF SCIENCE is more important than the recitations of theories and facts. We should describe stories of both successful and failed "rational" ideas (for instance, the displacement of Newton's physics of the universe by Einstein's; Popper's essay contains a nice discussion). We should also analyse the "supernatural" perspectives to test for ways they either conform to, or fail to meet the demanding criteria of Popper. Remember that the Popper method is ideologically impartial. Philip Johnson, the intellectual guru behind Intelligent Design, used Popper's approach to challenge the logical underpinnings of Darwinian evolution (see Johnson, 1991, p. 145-148, for a lucid summary of Popper's thesis). The question is not whether Johnson is entitled to challenge Darwinian evolution as valid science. Of course he is. The issue is, was the challenge launched within the bounds of Popper's criteria for valid science, and did Johnson come up with valid refutation?

References

Behe, M.J., 2008, The edge of evolution: the search for the limits of Darwinism: New York, Free Press, 320 p.

Dembski, W.A., 1999, Intelligent Design - the bridge between science and theology: Downers Grove, IL: InterVarsity Press, 312 p.

Johnson, P.E., 1991, Darwin on trial: Washington, DC, Regnery Gateway, 195 p.

Miller, K.R., 2008, Only a theory - evolution and the battle for America's soul: New York, NY: Viking, 244 p.

Popper, Karl, 1963, Science: conjectures and refutations, p. 43-86 in Conjectures and Refutations, London, Routledge (reprinted edition of 2002), 582 p.

Labels: blogs, evolution, pseudoscience

Another upcoming event that may be of interest to DC-area readers of this blog:

Labels: astronomy, evolution, teaching, virginia

From the satiric weekly The Onion: Evolutionists Flock To Darwin-Shaped Wall Stain.

Labels: evolution, humor

I saw Stephen Jay Gould speak once, in 1995 or 1996, at William and Mary. He showed us a series of 'evolution' cartoons, all bearing some humorous variation on the the linear progression of ape-to-australopithecine-to-caveman-to-modern-man theme. Gould used these cartoons an an example of the traditional human way of thinking about evolution: as a linear process leading to us as its final culmination. (Gould argued against this "line" of thought -- suggesting instead that evolution is best thought of as dendritic and arborescent.)

Anyhow: since I saw that talk, I've been very aware of the variety of cartoons on this cliche of a theme. There are a lot of them. I saw another one (by Ward Sutton) this evening while reading this week's New Yorker magazine:

Labels: art, evolution, humor

Browsing around the web this afternoon, killing time when I should be working on my Geotimes cartoon, I came across this essay on the New York Times website: "Musings inspired by a quagga"*, by Olivia Judson. Good stuff, although I do get tired of hearing that old "but the extinction that caused the death of the dinosaurs wasn't even the biggest" cliche. Inspired by a visit to the Museum National d'Histoire Naturelle in Paris, Judson explores the role of extinction in evolutionary processes. Worth a read.

*By the way, mark your calendars: August 12 is Quagga Day, so proclaimed by Ed Abbey. The one this year is the 125th anniversary of the death of the last quagga.

Labels: evolution, museums

Sorry for the lack of posting lately -- end of the semester crunch.

Just thought I'd post a link today, to an article in today's Times looking at some of Charles Darwin's botantical experiments.

Also, if anyone's in the neighborhood, I'll be giving a talk at the National Science Foundation in a couple of hours: "Geology Along the C&O Canal," starting at 12noon at NSF headquarters in Arlington, VA. Free & open to the public. Come one, come all... Sorry for the late notice.

Labels: evolution, plants

You no longer have to trek over to Cambridge University in order to sift through Charles Darwin's notes and papers. Now, it's all online, for anyone to access. The papers are all scanned in, so you can see his actual handwriting, sketches, etc. The image above, for instance, is the first written instance of Darwin's questioning the orthodoxy that species are stable (unchanging) entities over time. If species aren't stable over time, that means they can change over time, and those three words can be condensed into one word: evolution.

Also, NPR did a piece on the material being made web-accessible.

Labels: evolution, websites

It's rare for a terrestrial vertebrate to give up its lungs. But this fellow appears to have done just that. It's a newly-described species of frog from Indonesia. They get all their oxygen through diffusion over their skin surface, including skin flaps coming off the arms and legs. There are a few lungless species of salamanders and as well as caecilians, but this is the first frog: in dissections of eight specimens, nary a lung was found. CNN has more.

Labels: amphibians, evolution

Yesterday, Florida's state board of education felt obliged to stick the word "theory" into their description of the teaching of evolution. See this Reuters article for all the moronic details. Of course, evolution is a theory (i.e. well corroborated by many years of scientific testing & explanatory of a wealth of biological phenomena), so I don't have a problem with this definition per se, beyond exasperation with the motivations for its inclusion. I expect we'll see another lawsuit (a la Dover, PA) regarding this move, but in the meantime, it's an opportunity for science teachers to elucidate the difference between "theory" as it's used in science versus "theory" as it's used in casual conversation. So, the battlefield for teaching proper science shifts from Kansas to Pennsylvania to Florida. What would the Flying Spaghetti Monster say?

Labels: evolution, news, politics

This is an amphibian that you wouldn't want to meet in a dark alley: Beelzebufo, a monster fossil frog from Cretaceous sediments in Madagascar. It resembles the ceratophryine family of horned toads (sometimes dubbed "pac man frogs") that are now unique to South America, which the authors of a new study published in the Proceedings of the National Academy of Sciences.

Here, artist Luci Betti-Nash's whimiscal painting of Beelzebufo has it facing extant species Mantidactylus guttulatus, the largest frog in modern-day Madagascar.

The discovery of the big croaker suggests that South America and Madagascar were linked landmasses for much later than previously deduced from other lines of evidence. However, the newly-implied gap in time is substantial. Previously, it was inferred that the two landmasses separated 120 million years ago (Aptian), but the interpretation of this new fossil is that it must have been after 80 million years ago (Campanian). I'm not sure I buy that huge jump in separation dates based on a single genus of fossil frog: 40 million years is a substantial amount of time. On the other hand, sometimes "small" pieces of evidence like this lead to the development of new paradigms in scientific thinking. It has the potential to be the proverbial thread which unravels the sweater.

My caution: It's important to remember that fossils which resemble one another don't necessarily imply a continuous population: there's convergent evolution to consider, as well as the possibility of a highly conserved morphology over time. Both of these phenomena could maintain similar looking populations of "pac-man-esque" frogs on unconnected landmasses. And, I suppose, there's even the less-likely possibility of a "rafting" incident, where a few individuals ride a mass of vegetation across the ocean(s) from South America to Madagascar well after the two have separated. It happened to iguanas, after all: getting from South America to the Galapagos. Actually, with amphibians, their eggs can sometimes hitch a ride on bird feet too, colonizing distant new areas with ease. I'd like to know more about the presence or absence of relevant fossil frogs in Africa during the Cretaceous in order to better evaluate this new interpretation.

Read more about it in this New Scientist article. (I couldn't find the "cited" original article in PNAS, for some reason.)

Labels: amphibians, evolution, fossils, plate tectonics

I have a confession to make. Geology was not my first love: birds were. I spent one summer in college watching cattle egrets. That research project helped me get into ornithology, & I've kept "birding" as a hobby ever since. Even these days, I don't usually manage to get through a geology field trip without pointing and shouting "Look! There goes a pileated woodpecker!" (or a Cooper's hawk, etc.) Birds are everywhere, and they're great.
Accordingly, I was pleased to get these photos Friday from my colleague, NOVA biologist Bill Gorham.

This is a female cardinal (Richmondenis cardinalis). She has a unique look: her head is white! Bill calls her Ms. Whitey.

He tells me that the bird "has been a visitor in my yard for over a year. Last winter she just had a white 'collar' around her neck, then during the summer her whole head gradually whitened."
Bill continues: "I understand the term 'leucistic' applies because it is certainly not albinism but a loss of all pigments in certain areas... I would have to guess that the progressiveness has something to do with maturity. She mated and had chicks this past summer but I think she was a youngster last winter. She is also a member of a local tribe of cardinals that get bald every summer in July and August. First it was just one male (who we called 'Baldy') but now there are several males and several females. I don't think it is mites; I think it is some kind of heat response. When they molt in the fall they get a full head of feathers again."

A few points to be made here: (1) I like sharing images of natural oddities, which is why I'm posting these images [with Bill's permission] here; (2) I like having colleagues who share images of natural oddities [I like the fact I'm part of a community of people at NOVA who are curious about the natural world] and (3) I want to know what the heck is going on with this bird: I think it's weird that it's progressive whitening like Bill describes. I mean, I can see a certain region of the cardinal embryo mutating a gene (which subsequently gets copied & copied) leading to albinism in certain portions of the body (which then remain constant over the bird's life), but I find it truly odd that the area lacking pigment has increased over time. That's remarkable! If anyone has any insights into this "rare bird," let's hear it...

Labels: birdies, evolution, nova

In the spirit of the day, check out this article about mating at the National Zoo, here in DC (and a literal stone's throw from my apartment window).

Among the information featured:
when two females cheetahs are housed together, one or both females will shut down their ovulation, which makes it impossible to breed them until they are again separated.

Shanthi, the baby Asian elephant (who's now almost as big as her mom), was the result of artificial insemination. I remember visiting the Zoo shortly after Shanthi was born, and seeing video footage of her birth. Wow! Kablooey! That's a big package to drop!

The male Panamanian golden frog (pictured), which is extinct in the wild, will attach itself to the female for up to 120 days to make sure he's the one to fertilize her. Talk about clingy!

Also, you may be interested to know that some lowland gorillas will mate face-to-face, as the Wildlife Conservation Society reported this week, and was subsequently promoted by National Geographic.

Labels: dc, evolution

For Christmas a couple of years ago, I gave my family the black death, ebola, flesh-eating Strep, and stomach ache. Lest you think me some horrible person, I should point out that all of these nasty afflictions were represented by cute plush toys, courtesy of Giant Microbes. A picture of their version of E. coli (a.k.a. "food poisoning") is shown at left. They even have a toy version of the "bacterium" found in Mars meteorite ALH 84001!

I recently got an e-mail from the Giants Microbes people, and it reminded me of their unique products. I think they're great, and I just thought I'd pass that on. Several years ago, when I took a cross country road-trip, a Shigella bacterium from Giant Microbes was the Westy's trip mascot. Choose your microbe, folks. Make sure you wash your hands after playing with them.

Labels: evolution, products

First things first: colugos (pronounced cho-LOO-gos) are not "flying lemurs." Though they've been dubbed that, they are not lemurs, and they don't fly. They do glide, however, and that's what we're going to focus on today.

A few years ago, I visited the Malaysian state of Sarawak, on the island of Borneo. While there, I spent a couple of days in Bako National Park, a coastal forest park. Bako was great: bearded pigs, proboscis monkeys, pitcher plants: there was a bunch of cool, weird biodiversity there. One evening, while wandering back to my cabin, I saw some guys with spotlights roaming around in the forest. They were filming something up in the trees. These spotlights they were using were bright: it was professional gear. I asked who they were, and what they were looking at. Turns out they were from the BBC, filming an arboreal animal for footage to be included in a new program. This program was later watched by millions of people around the world: it was the groundbreaking series Planet Earth. The animal the Planet Earth team was pursuing in the forest was the Malayan colugo (Galeopterus variegatus).

Late last year, in Science, a study of a genetic marker shared by colugos and all primates established that the colugos were our order's closest living relatives, from which we diverged about 90 million years ago. They are fascinating creatures, even aside from this sense of kinship. I've seen colugos in two other places besides Borneo: Palau Tioman (off Peninsular Malaysia's east coast), and in Singapore (at the Zoo, but the colugos there are wild and uncaged). Each time, I've been astonished at how odd they look: clutching a tree they look like Gollum from The Hobbit: a srawny furry thing with improbably wide eyes. But then they launch themselves into the air, and they are transformed into a sleek gliding thing, like a swift kite, or an aerodynamic doormat. They slice through the air surprisingly quickly, and then flare up (stalling) just before their chosen tree, which they then land on. They crawl up the tree to a higher level on the trunk, and then repeat the gliding act.

A new study in the current issue of Proceedings of the Royal Society addresses the kinetics of colugo flight. Researchers captured a few colugos, shaved their backs (hah!) and then glued a little accelerometer there. This accelerometer works in the same way as the new generation of video game controllers: basically it can sense in what direction the colugo is moving, and how fast it's moving in that direction. The device looks like a little jetpack on the back of the colugos (as in the photo above), and it makes them look like some race of alien: a combination of the weird almost-a-primate morphology coupled with the shiny technological gadget latched to their backside. I'm not sure that I find the insights of the study all that fascinating (they basically confirm my common-sense read of colugo flight dynamics), but I think it's cool that people are out there quantifying such things using technology like this.

Accelerometer article in Proceedings of the Royal Society B.

Genetic relatedness of colugos to primates article in Science.


Eurekalert press release on the accelerometer study.

Labels: evolution, primates, tv

A paper in the new issue of Proceedings of the Royal Society announces the discovery of fossil evidence of the largest rodent yet recorded by science. The fossil reported is a skull, found in Uruguay. Of course, South America is home to the largest living rodent (the capybara, Hydrochoerus hydrochaeris), and it's no surprise that the continent should also have been home to the largest fossil rodent. The reason is that South America was a hotbed of mammalian evolution from about 65 million years ago (Ma), when it separated from North America, until about 3 Ma, when it reconnected with North America via the narrow Isthmus of Panama.

The new species, dubbed Josephoartigasia monesi, is closely related to another large extinct rodent called Phoberomys pattersoni as well as an extant (still living) species known as a pacarana (Dinomys branickii). The image at right, from the paper, shows a reconstruction of the head of J. monesi and a comparison with a pacarana.

P. pattersoni (from Venezuela) is estimated to have weighed about 700 kg, while J. monesi's bulk (extrapolated from the relative size of the skull) must have been about 1000 kg, a full metric ton.

As a continent hosting an independent trajectory of mammalian evolution, South America offers a beautiful contrast to Australia. Both continents were isolated from other continents for tens of millions of years, and their particular blend of mammals (& other species) evolved into unique & interesting forms. The South American experiment ended when it reconnected to North America at 3 Ma. At that time, mammals from North America trooped southward through Panama, and mammals from South America trooped northward. This flux of biodiversity is referred to as the Great American Faunal Interchange, and it dramatically reshaped South America's mammal assemblage. Saber-toothed cats (Smilodon sp.) was one of the turistas from the north, and it likely fed on big fat critters like J. monesi.

Other southward-bound groups included deer, bears, squirrels, rabbits, raccoons, and camelids (which went on to diversify into llamas & their kin). Northward-bound groups colonizing North America were fewer in number: the armadillos, the opossum, ground sloths (now extinct), and porcupines. Today, about 50% of South American mammal species have a North American origin, while only 20% of North American mammals have a South American origin. One of the reasons suggested for this lopsided distribution was that North America had been periodically connected to Eurasia (both east and west) via landbridges during the Cenozoic, and therefore North American mammals had been continually tested against the biggest continent's most competitive species. The North American mammals had already been forced to prove their mettle. South American mammals were living a life of blissful ignorance & luxury, and they experienced a rude awakening when their neighbors from the North came stampeding in. The competition between the two groups resulted in a lot of extinctions, and one of those appears to have been J. monesi. The fossils were found in a sedimentary unit usually interpreted to be about 2 Ma.

The image below shows the sheer size of the J. monesi skull by comparing it to a handheld rat. (Maybe a Norway rat? I can't tell, and the image from New Scientist doesn't specify the species.) It's a pretty extreme difference, of the same order of magnitude as the difference between an elephant and a hyrax.


Evolution can be really fruitful given a sufficient easing of competitive pressure. Island biogeography gives us some weird creatures (Komodo dragons, dwarf elephants, and Homo florensis come to mind as three Indonesian examples) if isolation is maintained over time. This new discovery from South America confirms the larger pattern by showing us that gigantism has happened in the rodent family, too. Discoveries like this (and the recent giant ape reported from China) prompt me to imagine other possible evolutionary trajectories: what about giant bats, or mouse-sized whales? Could evolution produce arboreal deer, or bears the size of Chihuahuas? I welcome your thoughts & creative speculations on potential record-breaking mammals.

Reference: Rinderknecht, Andres, and Blanco, R. Ernesto. The largest fossil rodent. Proceedings of the Royal Society, B. doi:10.1098/rspb.2007.1645 Published online.

For those without a subscription to the Proceedings, you can check out New Scientist's write-up of the research here.

Labels: evolution, fossils

In last week's issue of Science, Paul Silver (of DC's own Department of Terrestrial Magnetism at the Carnegie Institution) and Mark Behn (formerly a post-doc at Carnegie, and now at Woods Hole in Massachusetts) published a paper putting forward an intriguing idea: maybe plate tectonics proceeds in fits and spurts.

Silver and Behn note that most of the world's subduction zones are located in the circum-Pacific belt, and that the Pacific is getting smaller over time. (Subduction destroys oceanic crust, and since the Earth presumably isn't increasing or decreasing in volume, subduction in the Pacific is balanced by seafloor spreading elsewhere, like the Atlantic.)

The Pacific is "predicted" to close in about 350 million years, assuming that the tectonic plates continue to move at about the same rate they're moving now. The death of the Pacific would come as the Americas smash into eastern Asia and Australia, raising up a Himalayan/Appalachian style mountain belt. Silver and Behn posit that this would basically end subduction on planet Earth for a time. This was a startling idea to me at first, but then I thought, "Why not?" Then I thought, "I wish I'd thought of that."

My understanding of mountain belts comes from the Appalachians, which built up in three successive episodes called orogenies. Check out the diagram below (from the excellent textbook Essentials of Geology by Steve Marshak, that I use in my Physical Geology course at NOVA) and follow along so you can see why this new concept startles me a bit (but in a good way):

There used to be a big ocean basin off the "east" coast of North America that closed via subduction over the course of the Paleozoic Era. This extinct ocean goes by the name of Iapetus. This was not a simple event: it was more like a pile-up on the highway than a simple head-on collision. This ancient ocean basin was not just empty ocean. It also included islands and small chunks of continental crust ("microcontinents" like modern-day Madagascar). First a subduction zone developed out there in the ocean, closing a portion of it. This brought a chain of volcanic islands closer & closer to North America. The islands hit North America (around 460 million years ago), in a mountain-building event called the Taconian ("Taconic") Orogeny. Once that had happened, a new subduction zone developed on the ocean side ("outboard") of the islands/accreted terranes. That began to close another part of the Iapetus Ocean. Around 360 million years ago, that episode of subduction ended when a microcontinent (dubbed Avalonia) smacked into North America. This collision caused more mountains to rise: the Acadian Orogeny. Then yet another subduction zone, outboard of the newly accreted Acadian terrane, kept the closure of the Iapetus Ocean going, until finally the continent on the other side of the ocean (Africa) smashed into North America, raising more mountains. This is the Alleghenian Orogeny (sometimes spelled "Alleghany"), which really crumpled up the landscape, starting around 300 million years ago. The moment the Iapetus died was the moment Pangea was born.

I go into all this because the model of plate tectonic convergence the Appalachians display is one that says collisions between plates don't stop the overall convergent forces. As soon as one subduction zone is snuffed out, a new one develops outboard of the continent, where the weaker, denser oceanic crust gets shoved downward.

But does it actually work that way all of the time? Silver and Behn suggest maybe not. Maybe it's an "on-again, off-again" affair. They cite among their evidence an earlier orogeny, the Grenville Orogeny, which sutured together many continents at a much earlier time (about a billion years ago). When that collision had ended, the supercontinent Rodinia was born. Silver and Behn note a lack of volcanic activity around the world for hundreds of millions of years after the Grenville Orogeny (most volcanoes are caused by subduction). Rodinia did eventually break up amid much volcanic activity (including the eruption of the mid-Atlantic's infamous Catoctin Formation), and giving birth to the Iapetus Ocean basin in the process -- but that didn't happen for a long time after Rodinia got assembled. What gives? Does that mean subduction was inactive during that period?

They also offer a modern example: India and the Himalayas. 20 million years ago, India was a microcontinent out in the Indian Ocean, with a pavement of oceanic crust separating it from Eurasia. India moved north, the oceanic crust got subducted, and eventually India plowed into Eurasia, raising the Himalayas. But why hasn't a new subduction zone developed south of India? That would be what would happen if India's orogeny were following the Appalachian example.

Maybe plate tectonics has periods of intense activity (lots of subduction), but then has periods where it's "clogged up," and the movement of the plates slows. Eventually heat builds up in the underlying mantle (the source of plate movement) to the point where the mantle begins to convect more vigorously, and the plates start getting dragged around again. It's kind of a cool notion. I'd be interested to hear what you think about it. Please post any thoughts you have in the comments section below.

The whole idea reminds me of the concept of punctuated equilibrium, a model of biological evolution which bucked the long-standing notion (originated by Darwin himself) that evolution proceeded slowly and methodically over time. Thanks in part to an eye-opening appreciation of the Earth's immense age, the prevailing wisdom was that evolution was gradual, smooth.

Then (in 1972) Niles Eldridge and Steve Gould published a landmark paper that suggested otherwise. Instead of "gradualism," they argued, changes in populations of living organisms may have happened suddenly, experiencing a lot of change in a short period of time. Once equilibrium was achieved, the new status quo was preserved as a non-dynamic scene for a long time. (See image at left, which came from Wikipedia).

They cited the fossil record as their primary evidence: most of the change seen in fossils is a sudden switch of biological "regimes," with new fossils showing up, lasting a while, and then abruptly vanishing. I'm oversimplifying here, but I hope the analogy is clear: if evolution can do it, why not plate tectonics? Is there any reason to think plate tectonic motion couldn't happen in spurts of more activity followed by periods of quiescence? Ponder it...

Reference: Silver, Paul G., and Behn, Mark D., 2008, Intermittent plate tectonics?: Science, v. 319, p. 85-88, doi: 10.1126/science.1148397.

For those without a subscription to Science, you can read the press release about Silver and Behn's work that Carnegie put out by visiting their website.

Labels: appalachians, evolution, iapetus, plate tectonics

An article in the current issue of Current Biology describes a fascinating experiment with profound results. Like the best science, the experiment is simple and elegant. Researchers took blind cave fish from two different cave systems and mated them. The offspring had fully functional eyes. It turns out that different parts of the developmental system had broken down in the eye-producing mechanisms of these two different fish populations. In essence, they represented two different evolutionary trajectories. Technically, a certain spot in the genes for making one part of the eye mutated in one population of cave fish, and another spot (or "locus") mutated in a second population. The fish were both blind, but they were blind for different reasons. What was wrong with one was right with the other, and by breeding them good genes cancelled out bad, at least in some of the offspring. The remarkable implication is that researchers produced sighted fish from two populations that hadn't seen in over a million years! It's a powerful confirmation of their independent origins in different cave systems -- basically a subterranean example of how evolution takes populations of organisms in different directions based on their own individual circumstances and histories.

A summary of the work is found at National Geographic's website, for those of you who don't subscribe to Current Biology.

Labels: caves, evolution

The National Academies of Science released a new book yesterday about evolution. Aimed at the layperson, it explores the molecular, organismal, and fossil evidence in favor of evolution. The book suggests that accepting this evidence does not require losing one's religious faith, but instead that the two are compatible ways of viewing the world. The book is entitled "Science, Evolution, and Creationism." A PDF brochure offering an overview of the book is here, and the book can be ordered online here. Perhaps as a sign of things to come, the entire book is also available online, and you can access it here.

Labels: books, evolution