Chris writes, “I teach science at a public school in eastern Mass. This tattoo was taken from a New Yorker cartoon that my wife and I both have hanging in our classroom’s (she teaches science, too). Most people think it’s her Dad…there is a resemblance. When told it’s Charles Darwin, too many people reply, “Who’s Charles Darwin?”. It’s kind of sad. I call this Darwin Kong, the establishment trying to destroy Darwin for the same reason it destroyed Kong, it just didn’t understand him.”
In 1980, Walter Alvarez, a geologist at the University of California, Berkeley, and his colleagues proposed that the dinosaurs had been exterminated by an asteroid that smashed into the Earth. I was fourteen at the time, and that mix of dinosaurs, asteroids, and apocalyptic explosions was impossible to resist. I can still see the pictures that appeared in magazines and books–paintings of crooked rocks crashing into Earth, sometimes seen from the heavens, sometimes from the point of view of an about-to-become-extinct dinosaur. Suddenly the history of life was more cinematic than any science fiction movie.By luck rather than foresight, I eventually became a science writer. I had the good fortune to start the job in the early 1990s, as the impact story was still unfolding. Until then, I knew Walter Alvarez only as a name on a page. Now I could call Alvarez and talk to him about new evidence other scientists were finding to support his impact hypothesis–evidence showing not only that the impact did come at the end of the Cretaceous period, but even revealing where it hit: a site called Chixculub, along the coast of the Yucatán Peninsula. “It ties everything together,” Alvarez told me with delight in 1991. I had the wonderful privilege of watching the story continue to develop–as a bull’s-eye ring a hundred miles across came to light under the Gulf of Mexico, as a piece of the asteroid itself was fished from the Pacific.
By 1997, the story had matured enough that Alvarez himself was ready to offer a firsthand account in T. rex and the Crater of Doom. It is an intimately readable look at how great science gets done. Scientists notice odd things that seem out of place, they contemplate ludicrous hypotheses, and then they doggedly test those hypotheses for years. T. rex and the Crater of Doom illustrates an important rule about science: some of the most revealing discoveries come not from deep within a single discipline, but at the borders between disciplines. The impact hypothesis would probably have come to nothing if not for the combined efforts of experts on everything from geochronology to pollen fossils to nuclear explosions.
Chad writes, “Based on Huxley’s Man’s Place in Nature.” http://en.wikipedia.org/wiki/Image:Ape_skeletons.png
“I teach English at a community college in Kansas City. My tattoo is attached. You might wonder why I am sending a tattoo of a sailing ship to you. That’s not just any ship: it is the Beagle, in a famous image as it anchored off of the Galapagos. Darwin has long been one of my main intellectual heroes. In addition, I do teach science (evolution and climate change at various times) in writing classes because the “debates” about each represent much that is wrong with public discourse today and because we have a theme of informed citizenship in those classes; it is impossible to be an informed citizen without some understanding of what science is and how it works. For both of those reasons, teaching science in college writing classes is both relevant and very interesting”
I have been meaning for some days now to point your attention to my new article in the June issue of Scientific American called, “What Is A Species?” The hard copy is worth tracking down because it’s got a lot of excellent illustrations and sidebars. SciAm has the full article online for subscribers, and I’ve posted the text over at carlzimmer.com.
There’s so much I could say on the topic–pointing out how the recent news on polar bear extinction raises the question of how distinct polar bears are, for example–but I am scurrying in the shadow of a rising wave. (Attention people of Portland, San Francisco, and Seattle: please look at my book tour schedule!)
So let me direct your attention to a typically insightful blog post by John Wilkins about my article. John helped me enormously in understanding the nature of the species problem–especially its long tortured history.
After things settle down, I will take charge of my own blogging…
“I am an evolutionary biology graduate student working with some of the world’s earliest known HIV samples, trying to clarify the early evolutionary history of the virus. I was inspired by an elegant circle tree phylogeny my PI put together for a publication submission and I decided I had finally found something I connected with enough to get permanently put on my body.”
The platypus genome, which was published for the first time last week, has proved to be a Whitman’s sampler of biological treats. In case you missed the initial reports, you can check out a good summary from PZ Myers (and also take a look at Ryan Gregory’s take-down of the bad coverage). But today I just happened to come across another treat that, to my knowledge, hadn’t yet been picked out from the box. It’s a paper that came out today in Genome Biology. It concerns a very cool side of evolution that not many people appreciate. Species can evolve when their genes are modified, or when they acquire new ones. But the platypus turns out to be a great example of how species can evolve by losing genes.
When scientists sequencing the platypus genome matched up genes from the platypus to the genes from other mammals, a bunch of genes were missing from the duck-billed creature’s DNA. They were genes for protein-cutting enzymes called proteases. A closer looked revealed that these missing genes were for enzymes made only in the stomach. An even closer look revealed that these genes were not absent altogether, just disabled. Virus-like pieces of DNA had been inserted in the middle of these genes, making it impossible for the cells to make proteins from them. The scientists then looked at other genes for proteins that typically get made in the stomach. Some proteins, for example, create the acidic conditions in the stomach. The genes were broken in the platypus too.
Here’s what makes these losses really weird: Platypuses have lost their stomach. Just about all vertebrates have a stomach, a special, acid-drenched pouch with a number of specialized types of cells for producing digestive enzymes. The stomach of fish is build with the same developmental genes as ours. But for some reason, the platypus stomach has disappeared, leaving just as featureless tube connecting the esophagus to the intestines. Why platypuses would lose their stomachs while almost no other vertebrate has over the past 400 million years is a question I’d love to hear the answer to. (I didn’t even know to ask the question till I read the paper today.) And now scientists have found that stomach genes have performed the same disappearing act. But their remnants leave a sloppy trail of evidence of how this gastric bypass evolved.
“I studied geology for three years before I reached my major’s capstone course in paleontology. Therein, I became much more familiar with the subject that has since become my greatest scientific passion: evolution. Darwin’s breathtaking brilliance left me awe struck and I have since devoted much of my free time to studying natural selection, specifically, the origins of Darwin’s ideas. One of the basic foundations for Darwin’s discovery was the adaptation of different types of finches to various islands in the Galapagos. To commemorate my devotion, as well as to honor his genius, I got this tattoo of his first published drawing of said finches.”
Carl: If you haven’t read The Beak of the Finch, do so now.
Ben, a philosopher of science grad student, writes:
“Darwin sketched the great tree of life and as a philosopher of science and I endeavor to help to complete his project. ‘Metaphysics must flourish, he who understands baboon would do more for metaphysics than Locke’- I believe that by analyzing the universe underneath the lens of evolution we can come to complete Darwin’s project. Darwin, more so than any other great thinker, has provided humanity with an explanation for its existence.”
In case you missed it, there’s a great article in Smithsonian about hyena intelligence, focusing on the work of Kay Holekamp, the subject of my recent piece in the New York Times. The author, Steve Kemper, spent time with Holekamp in hyena country in Kenya, seeing just how brutal (and fascinating) life as a spotted hyena can be.
update: link fixed.