December 28, 2009

The End of Origins

image This year, the worldwide community of science has marked the bicentennial of Charles Darwin’s birth—and the 150th anniversary of the publication of On the Origin of Species—with dozens of evolutionary-themed meetings, books, review papers, and Science’s own monthly Origins series. In this blog, we’ve both joined in and reported on these celebrations, covering the meetings, expanding on the essays, and highlighting the most current research on evolution in all its many forms. Now the blog, like the year itself, draws to a close; this will be our final entry. We hope you have found it both diverting and useful.

Of course, Science’s interest in origins and all things evolutionary continues. For although 2009’s evolutionary parties are ending, the science behind them continues to serve as the firm foundation of modern biology as well as a rich source of new research. You can see all our Year of Darwin coverage in one place here, and you can continue to find the latest on evolution in online news at ScienceNOW and in the news and research in the magazine itself. Thanks for reading!

The Origins Blog Editors: Elizabeth Culotta, Elizabeth Pennisi, John Travis

If you're tired of watching It's a Wonderful Life or A Christmas Carol yet again, perhaps Darwin can occupy your cold winter nights. As a holiday treat, Origins would like to point out that this summer's Darwin Festival in Cambridge, U.K., has compiled videos of many of its sessions, which typically start with a reading from Darwin's correspondence. You can watch the videos directly here on the embedded media player, even skipping among the talks, or go to where they are posted here on YouTube. Enjoy.


by Lucas Laursen

Charles Darwin may have had his biggest impact on biology, but he began his scientific career as a geologist. So it’s appropriate that earlier this year, retired geologist John Ramsay, who had long studied the famed biologist’s life, accepted a commission to compose a Darwin-themed string quartet.

Darwin “did some pretty fundamental geological mapping," says Ramsay, drawing a parallel to his own geological career, during which he has drawn maps of the Scottish Highlands, South Africa, and the Swiss Alps. Ramsay says he and Darwin also share a penchant for putting "ideas that spring from other parts of one's life" into their current work. He notes that Darwin applied lessons from Earth's landscape to biology, adapting, for example, Charles Lyell's theory of gradual geological change to living things. Similarly, Ramsay's musical tribute draws on his own geology background. "Knowing Darwin's work, I wrote my quartet first of all on the evolution of the Earth," Ramsay says.

At the beginning of the piece, a disorganized Earth takes shape, with the core, mantle, and crust emerging into distinct musical themes. Life then arrives. Next, Ramsay writes in his concert notes, "the 'wriggly' primitive forms evolve into ... stronger and more continuous themes representing reptile and mammal forms."

Performed by the Fitzwilliam String Quartet, Ramsay’s composition premiered in Cambridge, U.K., during the Darwin Festival (Ramsay pictured above and Quartet playing pictured below) on 7 July 2009. The Darwin Quartet gave its second performance late last month during the triennial Cambridge Music Festival. The two festivals jointly commissioned the piece, and Ramsay hopes the Fitzwilliam Quartet will record the composition next year.

How did a structural geologist who spent his career climbing the academic career ladder at British and Swiss universities end up composing evolution-themed music? National service: After completing his Ph.D. in geology at Imperial College London, recalls Ramsay, "I became a cellist in an Army orchestra" in 1955. For 2 years, he toured Britain and British bases in Germany.

When his tour was over, Ramsay had to decide between pursuing music or geology. "I was hard-put," he says, "but I only started playing cello at 18, ... and that's a bit late for someone becoming a top professional." Instead, he continued with geology research and teaching at Imperial College, moved to the University of Leeds, and eventually settled in Zurich, Switzerland, with joint geology appointments at the Swiss Federal Institute of Technology (ETH) and the University of Zurich. But his other passion has come to the forefront again now that Ramsay has retired. Today, he teaches and composes music in the French hamlet of Cratoule, in a wine-growing region near the Rhône River whose landscape he describes as "wild without being fiercely wild."

His music hobby did not directly influence his geological career, Ramsay says, but a night class on life-drawing he took while in the Army probably did shape his interest in geological maps: "They are scientific records of the rocks on the Earth's surface, but they can be exceedingly beautiful things."

Ramsay says he tried to incorporate Darwin's ideas about the fleeting nature of any individual species into the epilogue of his composition; the music is meant to evoke a barren landscape, devoid of today's multitude of species. "Darwin showed that practically all the organisms that have lived on the Earth had a limited species-life, and practically all of them have died out and been replaced by new ones," Ramsay notes.

And what would Darwin have thought of the composition? "I don't know what he would make of my string quartet, [but] he was very worried toward the end of his life about where things were going," Ramsay says. "My idea is that perhaps the world will finish up like Mars, without life but still with a great deal of beauty."

Images courtesy Miranda Gomperts/Darwin Festival

darwin quartet.jpg

by Elizabeth Pennisi

Notho In my essay on the origin of flowering plants, I discussed many ideas related to how angiosperms came to dominate terrestrial ecosystems. Representing hundreds of thousands of species and 96% of all terrestrial vegetation, flowering plants are the most successful land plants on Earth. Researchers have long chalked it up to their flowers, which enlist insects and other animals to help them reproduce and spread. But two plant biologists credit the leaves instead. More leaf veins (left) made the plants better photosynthesizers, say Timothy Brodribb, a hydraulic physiologist at the University of Tasmania in Australia, and Taylor Feild, now at the University of Tennessee, Knoxville. "The importance of vein density has never before been so clearly presented," says Peter Wilf, a paleobotanist at Pennsylvania State University, University Park. Read about their compelling data and argument here.

Credit: Timothy Brodribb

December 3, 2009

On the Origin of Tomorrow

by Elizabeth Pennisi

image More than ever before, the future is in our hands. We are shaping not just our own destiny but also the destinies of much of life on this planet. That is the take-home message of the final essay, On the Origin of Tomorrow, in Science's Origins series.

As Carl Zimmer points out in this essay, Charles Darwin gave a nod to the future, finishing On the Origin of Species with a paragraph that talked about continuity: "... endless forms most beautiful and most wonderful have been, and are being, evolved.” He recognized that as long as the ingredients for the evolutionary process still exist, life has the potential to change. He didn’t believe it was possible to forecast evolution’s course, but he did expect humans would have a big effect—they had demonstrated this power already by domesticating plants and animals and driving some species to extinction. Darwin also expected that our own species would change.

As the world celebrates the 150th anniversary of the publication of On the Origin of Species this year, scientists continue to think deeply about what lies ahead. Some feel a new sense of urgency about understanding what might happen. Since Darwin’s day, humans have gained an unprecedented influence over our own evolution. At the same time, our actions, be it causing climate change, modifying the genomes of other organisms, or introducing invasive species, are creating new sources of natural selection on the flora and fauna around us. “The decisions we and our children make are going to have much more influence over the shape of evolution in the foreseeable future than physical events,” says Andrew Knoll, a paleontologist at Harvard University.

In this essay, Zimmer examines Darwin's perspective on the future and discusses how humans have helped to alter the course of their own evolution. He describes the ways humans have shaped the world around them—through global change, for example—and thereby affected the futures of countless other organisms and ecosystems. Finally, he ends with the question of whether humans will ultimately be smart enough to prolong the life of the planet.

Image: Katharine Sutliff

by Michael Balter

NEW YORK CITY—The exhibition of Vermeer’s The Milkmaid at the Metropolitan Museum of Art here is scheduled to end on 29 November, but don’t worry if you can’t get to the Big Apple in time to see that famous Old World painting. Just around the corner, New York University’s (NYU's) Institute for the Study of the Ancient World (ISAW) opened a stunning free exhibit* of more than 250 Old World artifacts on 11 November. These arts and crafts works from Europe’s Danube Valley are a bit older than Vermeer’s 17th century masterpiece, however: They date from 5000 to 3500 B.C.E., when farming was spreading into Europe from the Near East and the mobile, hunter-gatherer lifestyle was giving way to a sedentary, village-based existence.

OldEurope.18. Set of twenty one

The exhibit is a coup for ISAW, which was founded in 2006 amid considerable controversy. (The institute was made possible by a $200 million gift from donors Leon Levy and Shelby White, who were also collectors of ancient artifacts; some archaeologists believe that their collection has included looted objects.) The spectacular artifacts now on display, on loan from more than 20 museums in Romania, Bulgaria, and Moldova, have never been exhibited before in the United States. They feature dozens of terra-cotta figurines that some archaeologists have interpreted as “mother goddesses,” including a so-called Council of Goddesses from the site of Poduri-Dealul Ghindaru in Romania (see photo above), consisting of 21 small figurines and the tiny chairs some of them apparently sat on. The detailed and helpful explanatory legend, typical of the others in this exhibit, points out that the goddess interpretation is debatable, and that other hypotheses—for example, that the objects were dolls or playthings—must be considered.

OldEurope.8. the_thinker_hi Also on display is a pair of fired-clay figurines, including one called The Thinker, from the necropolis of Cernavodă in Romania, found in 1956 and dated to between 5000 and 4600 B.C.E. (shown at left). And the exhibit includes some of the more than 3000 gold objects from the Varna cemetery in Bulgaria, the richest burial ground in ancient Europe, dated to about 4500 B.C.E. The cemetery, discovered in 1972, provided important evidence that early European farming societies were not egalitarian as many archaeologists had assumed: The gold scepters, diadems, bracelets, necklaces, and animal heads were found in only 62 of the 310 graves, and the richest finds were restricted to only four—strongly suggesting that these communities were hierarchical.

The exhibit continues until 25 April. But if you miss it—or if you live today in Old Europe—the show moves to the Museum of Cycladic Art in Athens in October 2010.

*The Lost World of Old Europe: The Danube Valley, 5000-3500 B.C., Institute for the Study of the Ancient World, 15 East 84th Street, New York, NY 10028.


Set of Twenty-one Figurines and Thirteen Chairs: Elena-Roxana Munteanu/Neamţ County Museum Complex, Piatra Neamt

The Thinker and Female Figurine from Cernavodă: Marius Amarie/National History Museum of Romania, Bucharest

The National Science Foundation has released an online special report  on the influence of Charles Darwin on many walks of science. Evolution of Evolution: 150 Years of Darwin's On the Origin of Species features essays, videos, and podcasts from prominent researchers, as well as a timeline of advances in evolution, all beautifully crafted to enchant anyone curious about the history of life. Special topics cover anthropology, biology, astronomy, polar sciences, and geosciences, as well as Darwin.

Image credit: Illustrations by Nicolle Rager Fuller, National Science Foundation (background and center); © 2009 JupiterImages Corp. (top right); NASA, ESA, M. Robberto (Space Telescope Science Institute/ESA) and the Hubble Space Telescope Orion Treasury Project Team (bottom )

November 23, 2009

A Plethora of Hobbit Papers

by Elizabeth Culotta

Fans of Homo floresiensis will be happy this month, as the Journal of Human Evolution (JHE) has a special issue devoted to these diminutive hominins whose fossils were found on the Indonesian island of Flores. There’s also a new paper out in Significance, the Royal Statistical Society journal, in which William Jungers and Karen Baab add more analyses to back up the contention that the little people from Liang Bua cave are a new kind of hominin rather than diseased modern humans.

539px-Homo_floresiensis.fromwiki The JHE special issue covers every aspect of hobbit lore, including limbs, teeth, skull, geology, and stone tools. The papers have been posted online as they became available, and some of the work has been presented at meetings, so some findings have been in the news already. For example, at Science, we have recently covered the surprising similarity in stone tools from the H. floresiensis and H. sapiens levels, the hobbit’s unusual shoulder, and her primitive and strange feet. The special issue gathers an impressive amount of description and analysis in one place and includes a preface by co-discoverer Mike Morwood of the University of Wollongong and the University of New England, Armidale, and his colleagues.

Photo credit: Ryan Somma

by Virginia Morell


Scientists use the “molecular clock”—an estimated rate of DNA mutation—to date key events such as migrations and the divergence of species. But just how accurately the clock keeps time has long been debated. A new study of living and ancient Antarctic penguins, like those on Ross Island at left, suggests that DNA mutates six times faster than predicted. That could mean that some species—such as chimps and humans—could have split off from each other much more recently in time than previously thought. The finding should help improve the dating of relatively recent events, including when people domesticated various crops and animals, and when major human migrations occurred.

To use the molecular clock, scientists estimate the rate of mutation in DNA, estimating that the mutations occur in a steady, clocklike manner. For example, if a gene accumulates changes at a rate of five every 1 million years, 25 mutations in a genetic sequence would mean that the sequences had diverged 5 million years ago. The technique has been used to estimate when humans separated from the other great apes, to estimate the arrival of people in the Americas, and to create evolutionary trees for many species. Molecular clocks are usually calibrated by using the age of a known species from the fossil record. But scientists disagree about the speed or rate at which mutations occur and under what circumstances the rate is influenced by natural selection or other factors.

To see just how accurate molecular dating is, David Lambert, an evolutionary biologist at Griffith University in Queensland, Australia, and colleagues looked at Adélie penguins. These Antarctic birds may be the best species yet for building an accurate clock, the team argues, because scientists can study the genetic sequences of both living and ancient members of the species. The penguins generally return each year to the same nesting ground; thus, each rookery can have layers of bones dating far back in time. Indeed, the birds have nested at some rookeries for 44,000 years. "You can take blood samples from the living penguins and then literally collect the bones of their ancestors" in the ground below, says Lambert, because the penguins usually return to their natal colony to mate. Other studies usually can only compare genes from organisms separated in time by millions of years. 

Using modern blood and ancient bone samples, the researchers extracted the entire mitochondrial genome from 12 modern and eight ancient penguins, including two that were dated to 44,000 years ago using radiocarbon methods. They then compared the mitochondrial DNA of the living penguins with the ancient ones to determine the number of mutations that had occurred. Because they had radiocarbon dates for the ages of the ancient penguins, the scientists could accurately measure the bird’s average mutation rate, ultimately calculating that its mitochondrial genome had evolved at a rate two-to-six times faster than previously estimated.

The team's findings, reported in this month’s issue of Trends in Genetics, support similar results for faster clocks in mitochondrial sequences in cattle. But in this new study, the researchers succeeded in calculating the rate of mutation within almost the entire mitochondrial genome, providing “more conclusive evidence,” for a rapidly ticking clock, says Dee Denver, an evolutionary biologist at Oregon State University in Corvallis and one of the paper’s co-authors. They also focused on a region of the genome that is known to not be influenced by natural selection, they write in the paper. Thus, they say that the resulting clock is not merely a reflection of penguin evolutionary history and can be applied to other species.

"It's novel and groundbreaking work," says Mark Hauber, an evolutionary biologist at Hunter College in New York City, who was not affiliated with the study. "It's a significant discovery," adds Elizabeth Matisoo-Smith, a biological anthropologist at Otago School of Medical Sciences in Dunedin, New Zealand, who expects it will help resolve several discrepancies between genetic data and the archaeological record, such as the peopling of the Pacific Islands and the Americas. However, the penguins’ rapid clock "should be confirmed on a wide diversity of species" before being adopted as the new standard, says Robert Wayne, an evolutionary geneticist at the University of California, Los Angeles.


Photo credit: Euan Young

by Elizabeth Culotta

In my essay on the origin of religion earlier this month, I describe new research tackling the question of how belief in unseen deities arose. One leading model from cognitive science suggests that religion is a natural consequence of human social cognition and that we are primed to see the work of another thinking being—an agent—in the natural world and our lives. But a person of faith might give a different kind of answer: Religion arose because divinity exists, and belief in deities represents the human response to it.

Does the cognitive science model conflict with that religious perspective? Some creationists find the research an attack on faith. But the scientists I interviewed said that the question of whether God exists is distinct from their research. For example, Deborah Kelemen of Boston University, whose psychological studies have found that children and adults have a natural penchant for creationist explanations, says that her work “does not speak to the existence of God; it speaks to why and how we might believe. Whether God exists is a separate question, one we can’t scientifically test.” Those who are upset by the idea that human minds are likely to construct gods, or that evolution has shaped religion, “are misreading the message of this work,” she says.
Charles Darwin neatly articulated the distinction between studying the mechanism of religious belief and its truth. When considering the origin of religion in The Descent of Man, he wrote: “The question is of course wholly distinct from that higher one, whether there exists a Creator and Ruler of the universe; and this has been answered in the affirmative by some of the highest intellects that have ever existed.” (He did not, however, report how he himself stood on the question of God’s existence.)

Some scientists say that the cognitive model of religion is compatible with belief in God. The science explains why humans are receptive to religion, a notion that theologians of various religions have explored, says Justin Barrett of the University of Oxford in the United Kingdom, who studies the psychology of belief and is an observant Christian. “Embedded in all of us is a receptiveness to the idea of transcendence—an idea you see in many of the world’s religions. From their point of view, we trot out the scientific evidence for this receptiveness, and their response is, ‘Yeah, right, we knew that,’ ” says Barrett.

Barrett and others do sometimes get letters from angry believers, but they also receive letters from irate atheists, who don’t buy the notion of religion as part of human nature. “I’m not seen as a friend of atheists either,” says Jesse Bering of Queen’s University, Belfast. “I’m arguing there are no atheists proper.”

All the same, some scientists do see a potential conflict between the cognitive research and faith, if researchers one day find that belief in God stems from trivial or untrustworthy psychological reasons. “The study of why people believe in God can shed light on whether they do so for a good reason or a bad reason,” says Paul Bloom of Yale University. “If I were religious, this would matter to me a lot.”