Adventures in evolution
Posted: Wednesday, February 11, 2009 9:26 PM by Alan Boyle
Hulton Archive / Getty Images file
An engraving shows the HMS Beagle being greeted by Fuegian natives as it sails
through the Strait of Magellan in 1834 with naturalist Charles Darwin aboard.
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Evolutionary biology isn't just something you do in the lab or the library: Over the past two centuries, scientific pioneers have had to weather seasickness, survive shipwrecks and watch out for polar bears while they ferreted out the facts.
In his latest book, "Remarkable Creatures," molecular biologist Sean B. Carroll recounts the rip-roaring adventure tales behind the great advances in the theory of evolution.
Carroll, a professor at the University of Wisconsin at Madison, is one of the foremost researchers in evo-devo. That may sound like the name of a techno-rock band, but the phrase actually refers to evolutionary develomental biology - that is, the study of how different organisms develop, and what those differences tell us about evolution at work. For example, what kinds of genetic toolkits are responsible for ultraviolet vision or antifreeze-laden blood, and what causes those traits to emerge?
UW-Madison |
Sean B. Carroll is a
biologist at the University
of Wisconsin at Madison.
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Carroll has surveyed the frontiers of evolutionary biology in a series of books - including "The Making of the Fittest" and "Endless Forms Most Beautiful," which are being developed into a documentary TV project for PBS' "Nova" series. "Remarkable Creatures" takes a slightly different perspective, focusing on how scientist-explorers helped open up that frontier over the past two centuries.
The most famous evolution expedition was Charles Darwin's five-year journey on the H.M.S. Beagle. That round-the-world voyage gave him a bad case of seasickness - but also gave him the raw material he needed to write "The Origin of Species," which was published 150 years ago. You can read Darwin's travelogue, "The Voyage of the Beagle," as a free online book, but it's even more fun to experience it as an illustrated blog.
During that trip, Darwin's study of fossils and the famous finches of the Galapagos Islands led him to the conclusion that new species originated through a natural process, rather than through a Genesis-style series of special creations. Darwin kept that conclusion to himself (and a few of his close friends) for two decades, fearful of the outcry that might result.
Ironically, Darwin's voyage spurred another naturalist and collector, Alfred Russel Wallace, to go on his own scientific expedition to the Amazon and solve the mystery surrounding new species. After four years of collecting, Wallace began the homeward voyage to England with a rich bounty of notes, drawings, specimens and even live animals. Unfortunately, a fire swept through the ship, and Wallace lost nearly everything.
"From the lifeboat he watches the ship burn and sink with all his specimens and animals. ... Four years of work is going down to the ocean bottom," Carroll said. Wallace and his fellow travelers spent 10 days on that leaky lifeboat before they were picked up by rescuers.
Houghton Mifflin Harcourt |
"Remarkable Creatures" recounts
tales of evolutionary adventurers.
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That would take the enthusiasm over exploring out of anyone. Wallace didn't give up, however. He went on an even longer, more arduous expedition to the Malay Peninsula, and came up with the basic idea behind Darwinism even before Darwin had published his theory.
"These men had parallel experiences, and they independently seized on this idea of natural selection," Carroll said. When Darwin saw that Wallace was on the right track, he decided to go public as well. The leading lights of the British scientific establishment worked out an arrangement for a joint presentation of the two men's views on the "survival of the fittest."
Over the past 150 years, Darwin may have captured far more of the scientific spotlight than Wallace has. But when it comes to enduring the hardships of scientific exploration, I'd have to say Wallace takes the prize. And those are just two of the adventures retold in Carroll's book. Here's an edited Q&A transcript that delves into three of the other tales:
Cosmic Log: Does it take a particular breed of scientist to become an explorer?
Carroll: Let me give you a thumbnail picture: Besides the naturalists, the other "breed" of scientists who like traipsing through jungles are the paleontologists - because they have to find somewhere in the earth's crust the vestiges of life's history. Where do you go in the world to find these things? Darwin's "Origin of Species" really set the agenda, because as much as Darwin was a good fossil collector, as convinced as he was about the deeper history of life, he was pained by the fact that he didn't have transitional fossils at the time of "The Origin of Species." Well, the last 150 years, paleontologists have been digging them up. And some of those paleontologists were directly inspired by Darwin.
Eugene Dubois was a physician, climbing very fast in the ranks in Holland. But he was well-versed in natural history, well-read on the emerging evolutionary theory. And in the 1880s he decided the most important thing he could do was find a missing link between apes and humans. So he said, "To hell with it." He chucked his medical career, took his wife and young baby all the way to the Dutch East Indies. He went there because it was territory governed by the Dutch, and the way he supported himself was by signing up for an eight-year stint in the Dutch army.
So he abandoned a comfortable career in Amsterdam and started exploring the jungles and caves of Sumatra. He struck out in Sumatra, and so he decided to explore Java. He gets four years into this - he's suffering from malaria, he's dodging tigers, it's ungodly hot. But here's the thing: He assumes that he's going to find human ancestors in Java. That was a big assumption right there, let alone that he'd find the right material in the right place. This was a dart toss, right? And son of a gun, they find a molar, a skullcap and a thigh bone. This is what we know today as Homo erectus.
Dubois was hell-bent. This was as single-minded an expedition as I know about. To illustrate how fortunate he was, all sorts of people followed Dubois to Asia and to Java, and nobody found anything for 40 years.
Q: Does it strike you that to some extent, the destination determines the nature of the discovery? For example, if Dubois had gone to Africa instead of Asia, the course of the study of human evolution might have been different.
A: Yup, it could have been different - had he found something. But the Leakeys show you how hard that is. In the 1920s, the Leakeys started their excavations in east Africa. Contrary to Dubois, Louis Leakey was convinced that the cradle of mankind was Africa. We all accept that now, but you've got to realize that for a long time after "The Origin of Species," and especially because of things like Dubois' discoveries, most people were thinking about Asia.
Leakey was definitely bucking the prevailing wisdom. What got him started was that as a child he was finding stone tools. Well, obviously, stone tools had to have toolmakers, so he made it his mission, his life's ambition, to find the bones of these toolmakers. He and his wife spent 31 years looking in east Africa. Fifty years ago this summer, Mary Leakey found the first hominid bone in Olduvai Gorge.
So if you ask me what kind of character it takes, I don't even know if persistence is the word that describes that. Clearly they had to believe, scientifically, it was reasonable to say "if we're finding tools, there must be toolmakers." So you stay at it. But 31 years is an awfully long time to wait before you find a skull and hold it up to the world.
Now, when they held it up to the world, the world changed. The attention on human origins swung back to Africa for good, and in a few years they found Homo erectus and Homo habilis at Olduvai Gorge. Their funding went up, more people came to the field to help with the search, and the pace of discovery quickened. But that was after a 31-year mission that was fairly lonely, where you're living in the bush without any money. They were a pretty determined pair.
Q: So is the species of the scientist-explorer heading toward extinction? You could cite a couple of reasons. One is that the number of unexplored places is lower, and also you just don't see as much of the patience or persistence or sheer insanity required to spend so much time looking for discoveries.
A: Well, I'll counter that with the tale of Neil Shubin. Neil and his colleague, Ted Daeschler, are trying to find fossils that connect fish to the first four-legged animals. Long experience told them the right sort of age of rock they should be looking for, the right sort of deposition they should be looking for. When they combed the geological archives, it pointed them to the Arctic.
They mounted their first expedition there in 1999, and it was tricky, because they're up above the Arctic Circle. The season is short. Logistics are very complex. They have to helicopter from place to place. It's the land of polar bears. Weather is horrible, even during the short field season.
The first season, they find nothing. Second season, they find fossils, but there's nothing new. It's not until the fourth season that they strike paydirt. And it's spectacular. These Tiktaalik fossils they find are large and in great condition, of varying sizes that give you a whole lot of anatomy. It's exactly what they were looking for. Knowing these people, I think that passion is still there. I'm very comfortable saying it's widespread.
Now, granted, we try to travel with a little more safety - with a satellite phone, as opposed to the days when Darwin tried to communicate with John Henslow, his mentor, and didn't get a reply for six months. The hazards are managed a little bit better, and you're standing on 150 years of knowledge, so the guessing is reduced. But the desire to explore the unknown? That desire is absolutely undiminished.
To hear Carroll talk about Darwin and Wallace, check out this report from NPR's Joe Palca. For additional food for thought on Darwin Day, take a look at these other Cosmic Log postings:
And for much, much more, search for Darwin on msnbc.com.
