Good Science Writers: Sean B. Carroll

 
Sean B. Carroll is Professor of Molecular Biology and Genetics at the University of Wisconsin in Madison, Wisconsin (USA).¹ His research interests focus on evolution and development, mostly in fruit flies and other insect. Carroll is one of the leading advocates of a new approach to evolution arising out of what we have learned from animal development ("evo-devo"). (See the official Sean B. Caroll website.)

He is co-author on two textbooks: From DNA to Diversity: Molecular Genetics and the Evolution of Animal Design (2nd ed, 2005) with Jen Grenier and Scott Weatherbee; and Introduction to Genetic Analysis (9th ed., 2007) with Anthony Griffiths, Richard Lewontin, and Susan Wessler. Sean B. Carroll has written two trade books: Endless Forms Most Beautiful: The New Science of Evo Devo (2005) and The Making of the Fittest (2006).

Sean B. Carrol was not included in Richard Dawkins' book: The Oxford Book of Modern Science Writing

The excerpts below are from The Making of the Fittest. This is a book that emphasizes the role of natural selection in evolution.

It may be the most remote place on Earth.

Tiny Bouvet Island is a lone speck in the vast South Atlantic, some 1600 miles southwest of the Cape of Good Hope (Africa) and almost 3000 miles east of Cape Horn (South America). The great Captain James Cook, commanding the HMS Resolution, tried to find it on his voyages through the Southern Ocean in the 1770s, but failed both times. Covered by an ice sheet several hundred feet thick that ends in sheer cliffs, which in turn drop to black volcanic beaches, and with an average temperature below freezing, it still doesn't get many visitors.

Fortunately, for both my story and natural history, the Norwegian research ship Norvegia made it to Bouvet Island in 1928, with the principle purpose of establishing a shelter and a cache of provisions for shipwrecked sailors. While on Bouvet, the ship's biologist, Ditlef Rustad, a zoology student, caught some very curious-looking fish. They looked like any other fish in most respects—they had big eyes, large pectoral and tail fins, and a long protruding jaw full of teeth. But they were utterly pale, almost transparent. When examined more closely, Rustad noticed that what he called "white crocodile fish" had blood that was completely colorless.

Johan Ruud, a fellow student, traveled to the Antarctic two years later on the factory whaling ship Vikingen. He thought the crew was pulling his leg when one flenser (a man who stripped the blubber and skin from the whale) said to him, "Do you know there are fishes here that have no blood?"

Playing along, he replied, "Oh, yes? Please bring some back with you."

A good student of animal physiology, Ruud was perfectly sure that no such fish could exist, as textbooks stated firmly that all vertebrates (fish, amphibians, reptiles, birds, and mammals) possess red cells in their blood that contained the pigment hemoglobin. This is as fundamental as, well, breathing oxygen. So when the flenser and his friends returned from a day's efforts without any blodlaus-fisk, Ruud dismissed the idea as shipboard lore.

Of all the scientists in the world today, there is no one with whom Charles Darwin would rather spend an evening than Sean Carroll.

         Michael Ruse

He wasn't looking for a new kingdom.

Microbiologist Tom Brock and his student Hudson Freeze were prowling around the geysers and hot springs of Yellowstone National Park one day late in the summer of 1966. They were interested in finding out what kinds of microbes lived around the pools and were drawn to the orange mats that colored the outflows of several springs.

They collected samples of microbes from Mushroom Spring, a large pool in the Lower Geyser Basin whose source was exactly 163 degreed F, thought at the time to be the upper temperature limit for life. They were able to isolate a new bacterium from this site, a species that thrived in hot water. In fact, its optimal growth temperature was right around that of the hot spring. They dubbed this "thermophilic" creature Thermus aquaticus. Brock also noticed some pink filaments around some even hotter springs, which raised his suspicion that life might occur at even higher temperatures.

The next year, Brock tried a new approach to "fishing" for microbes in the hot springs of Yellowstone. His fishing tackle was simple: he tied one or two microscope slides to a piece of string, dropped it in the pool, and tied the other end to a log or a rock (don't try this on your own—you will be arrested and quite likely scalded or worse). Days later, upon retrieving the slides, he could see heavy growth, sometimes so much that the slides had a visible film. Brock was right that organisms were living at higher temperatures than had previously been thought, but he did not imagine that they were living in boiling water. And they weren't just tolerating 200 degrees F or more—these organisms were thriving in smoky, acidic, boiling pots such as Sulpur Cauldron, in the Mud Volcano area of the park. Brock's Yellowstone explorations opened eyes and minds to the extraordinary range of life's adaptability, identified bizarre but important new species such as Sulfolobus and Thermoplasma, and launched the scientific study of what he called "hyperthermophiles," lovers of superheat.

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1. Sean B. Carroll is the biologist. Sean Carroll is the physicist at the California Institute of Technology and one of the authors on the blog Cosmic Variance.