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July 2009 Archives

BrocaHuman

Why don’t chimpanzees have language the way humans do? Researchers are confident that it has something to do with differences in their brains that arose sometime in the past 5 million to 7 million years, when the chimp and human lines went their evolutionary ways. But exactly what differences account for human language are not entirely clear. Size might have something to do with it, because the modern human brain is about 3.6 times as big as that of a chimp. And yet chimp brains appear to share many features with their human counterparts, including a frontal lobe region called Broca’s area (purple in image) that in humans is closely associated with speech and language.

Most studies of Broca’s area in human brains have concluded that it is larger on the left side than the right, which seems to correlate with the finding that 94% of right-handers do most of their speech and language processing on the left sides of their brains. Scientists had long assumed that this asymmetrical enlargement of Broca’s area in humans was key to language abilities. But in 2001, researchers led by William Hopkins, a primate neuroanatomist at Emory University in Atlanta, began reporting that the brains of many apes also had asymmetrical Broca’s areas. The first such report, in the 29 November 2001 issue of Nature, found enlarged left-side Broca’s areas in the brains of chimpanzees, bonobos, and gorillas. And in a 2008 paper in Current Biology, Hopkins and his colleagues reported that Broca’s area is activated in chimp brains when they communicate with gestures or vocalizations. Hopkins and his co-workers concluded that the enlargement of Broca’s area, and its role in communication, began before the chimp-human split and was not unique to humans.

Yet a new paper, published online last week in Cerebral Cortex, challenges some of these findings and argues once again that the language centers of human brains are special.

In Charles Darwin’s 19th century, things were changing for women, as campaigns for equality and feminist ideals emerged.

During this time of social transition, Darwin encouraged many aspiring female scientists of the day to push on with, and even publish, their own work. Now, a new project run by the Darwin Correspondence Project (DCP) at the University of Cambridge will transcribe letters to and from Darwin’s 148 female correspondents to reveal more about how he helped change the scientific playing field for women.

“[This is] a side of Darwin that you wouldn’t necessarily know about,” says project director Jim Secord. It’s true that Darwin still believed that women were best adapted for carrying out domestic tasks, acknowledges Secord, but unlike others at the time, he was “quite open minded to women having an intellectual role” and took the work of female scientists seriously.

Among others, American botanist and entomologist Mary Treat received the support of the famous scholar. She turned to Darwin after her mentor Charles Riley berated her work on sex determination in larval butterflies. Treat had found that larvae that ate more tended to become females, while those deprived of nutrition more often became males. After presenting her findings to Darwin in a letter, he encouraged her, writing: “Your observations and experiments on the sexes of butterflies are by far the best… which have ever been made.” Darwin said she should repeat and record the work and consider sending it to a “well-known scientific journal”. Treat later published the work in The American Naturalist.

The project will also explore Darwin’s interaction with women in his family. His youngest daughter, Henrietta, was a particularly strong influence: “She was quite an active editor,” says Secord, especially on Darwin’s book The Descent of Man and Selection in Relation to Sex , as revealed by letters to Darwin’s publisher, John Murray, and marked copies of the book.

The DCP has been awarded £480,000 over three years from The Bonita Trust for the project. Along with producing academic papers on research into the letters, the team will make the letters available to the general public on its website.

--Claire Thomas

Mise en page 1 (Page 28 - 29)

We all loved cartoons as children, and many adults still do. They are funny, and they usually tell a story, either in consecutive panels, as in comic strips, or by using animation techniques, as in motion-picture cartoons. The modern comic strip dates from the late 19th century, when artists such as Rudolph Dirks, inventor of the Katzenjammer Kids, began drawing them for American newspapers; and the animated cartoon was born in 1907, when French artist Émile Cohl began drawing people and other images directly onto movie film.

But a special exhibit in the south of France claims that the origins of the cartoon can be traced back much further, to the earliest known cave art more than 30,000 years ago. The exhibit, at the prehistory center of the Pech-Merle Cave in the Lot Valley, is titled “Préhistoire de la Bande Dessinée et du Dessin Animé” ("Prehistory of the Cartoon Strip and the Motion Picture Cartoon"). It was mounted by prehistorian and filmmaker Marc Azéma of the University of Toulouse in France. Azéma argues in nearly 30 beautifully illustrated panels that early cave artists used some of the same animation techniques that cartoonists use today. And although the exhibit is intended for the general public, it is based on Azéma’s Ph.D. thesis research, which he summarized in a 2005 paper for the International Newsletter On Rock Art, which is edited by French cave art expert Jean Clottes.

Earlier this month, I visited the exhibit and the spectacular Pech-Merle Cave, one of the small number of French painted caves still open to the general public. In panel after panel, Azéma shows how cave artists created the sensation of movement in the animals they drew both by superimposing multiple numbers of legs, heads, and other body parts and by orienting groups of animals in dynamic ways that suggest motion, which is similar to what animators do today. In the Lascaux Cave, for example, some 20 horses were drawn with multiple heads, legs, or tails. One Lascaux horse was drawn with five superimposed heads and several manes. Similar techniques were used at La Marche Cave in France’s Vienne department, where a horse was drawn with so many heads, tails, and backsides that it looks like a blur on the cave wall.

Azéma finds such animation techniques even in the earliest known cave art, at the 32,000-year-old Chauvet Cave in the French Ardèche (see panel above), where a bison is drawn with eight legs. Azéma even suggests that the artist who painted Chauvet’s famous Horse Panel, which features four superbly drawn horses’ heads, might have intended to depict one horse in motion—although he adds that it is not possible to know for sure.

As a special bonus, the exhibit includes cartoon strips drawn by Gilles Tosello, an artist and prehistorian at the University of Toulouse who conducts research at Chauvet. Tosello portrays what he imagines to be the origins of one of Chauvet’s most spectacular artworks, Le Grand Panneau (The Great Panel), which features troops of horses, rhinoceroses, and bison apparently being pursued by lions. In Tosello’s telling, a young woman artist sees the predatory attack from her hiding place in tall grass nearby and then shows her fellow prehistoric humans what she saw by painting the scene on the wall of the cave.

The exhibit continues until 3 November.

—Michael Balter

 

Photo credit: Marc Azéma / Passé simple / le Centre de Préhistoire du Pech-Merle (Lot) / le Musée de Préhistoire d'Orgnac - Grand Site de France (Ardèche)

July 24, 2009

A Streetcar Named Darwin

Darwin car

From the Random Samples page in the current issue of Science:

Some streetcar riders in Cologne, Germany, are getting a dose of evolutionary biology during their daily commute. Twenty art students at the University of Cologne, directed by biologist Daniel Dreesmann, artist Volker Saul, and art professor Silke Leverkühne, celebrated the Darwin Year by creating the "Evolution Erfahren" (experience evolution) streetcar, which will run for the rest of the year on the city's regular routes. The car is covered inside and out with artwork exploring Darwin-related themes, including the evolution of birds, evolution and medicine, and "evolution in our backyard"—for example, a recently evolved fish species that lives in the Rhine. "It's not a moving textbook," Dreesmann says. "It's designed to make people curious." For those who can't catch the streetcar in person, the Volkswagen Stiftung, which funded the project, this week published a catalog of the artworks created for the project

--Gretchen Vogel

Image: WWW.EVOLUTION-ERFAHREN.DE

Charles Darwin’s book On the Origin of Species by Means of Natural Selection, or the Preservation of Favoured Races in the Struggle for Life contained his first thoughts on evolution. Now, 150 years later, computer scientist Greg McInerny is turning the idea on its head, drawing diagrams showing the “evolution” of the book as new editions were published. In the editing process, certain sections became “extinct,” that is, did not make it to the next edition. Other, stronger sections avoided the editor’s chopping block to make it into the final sixth edition—a kind of survival of the sentences—and in some cases, entirely new sections of text were added.

Together with London-based m_ed_5_webvisual artist Stefanie Posavec, McInerny has devised the (En)tangled Word Bank, which shows the construction and evolution of the book. In some cases, the editions varied quite a bit, says McInerny, who is based at Microsoft Research in Cambridge in the United Kingdom. “For the second edition, Charles Darwin wanted a more popular and available version,” he says, so Darwin inserted references to a creator who may have been behind the initial creation of life. In the sixth edition, he added a whole new chapter discussing the support and criticism that had surrounded the book.

The diagram (left) represents the fifth edition. In it, the rim consists of four layers. The outer ring represents sentences; the next ring in signifies paragraphs, then subchapters and chapters follow. The central branching design represents the same divisions, with chapters at the base and sentences at the tips. The green “leaflets” show sentences that have “survived” multiple editions, and orange “leaflets” represent those that are “dying” and will be absent from the next edition. The darker the green or orange, the longer that sentence has survived through multiple editions.

(En)tangled Word Bank is an example of a “literary organism,” a structure devised by Posavec to show visually how books are constructed from their basic units. Her first such work was based on Jack Kerouac’s novel On the Road.

—Claire Thomas

Diagram: Greg McInerny and Stefanie Posavec

The May Origins essay examined the origins of the immune system but focused exclusively on the microbial defenses animals use. Here, Claire Thomas examines what scientists are learning about the evolution of plant immunity—and whether there are any connections with animal immunity.

Most of us know the basics behind the “adaptive” immune system in mammals—thanks to school biology lessons about white blood cells that specifically attack and engulf pathogens or make antibodies that grab those microbes—but how do plants protect themselves?

At first glance, plant immunity is far simpler: Plants rely partly on their rigid cell walls to keep out microbes. They don’t have a circulatory system and therefore no roaming immune cells to track down bacteria and viruses. But they do have one fundamental thing in common with mammals: a basic “innate” immune system. In mammals, the white blood cells that make antibodies or specifically target microbes rise up only after this innate arm carries out the initial immune response to a pathogen, typically causing inflammation. Plants, on the other hand, can only use their innate responses to fend off pathogens.

But as scientists have compared plant and animal immunity, they’ve been struck by something surprising. “The current evidence and belief is that there is tremendous similarity between animal innate and plant immune systems,” says Dan Klessig, a plant pathologist at Cornell University. In fact, both systems use similar receptors to detect invading pathogens.

Which raises an intriguing issue: Did a primordial ancestor common to plants and animals evolve a basic innate immune system, which began to differ in the two lineages once they split (divergent evolution)? Or did plants and mammals evolve innate immunity independently but end up with similar mechanisms (convergent evolution)? That’s something that scientists have puzzled, and argued, over. “It’s an area where there’s more debate than data,” says plant geneticist Peter Tiffin of the University of Minnesota, Twin Cities.

1 © 2007 Photo  P.Plailly  Eurelios - Reconstruction  Atelier Daynès Paris In my article in last week’s issue of Science, ”Bringing Hominins Back to Life," I feature several “paleoartists” who create lifelike models of our ancestors for museum displays, magazine covers, and documentaries. All of these artists owe their credibility and success to close collaborations with human evolution experts, who serve as reality checkers for the scientific validity of their reconstructions.

For example, an early influence on John Gurche, a paleoartist in Trumansburg, New York, was primatologist Adrienne Zihlman of the University of California, Santa Cruz. Gurche contacted Zihlman in the early 1980s and asked if he could participate in her dissections of great apes. Zihlman alerted Gurche whenever a freshly deceased specimen arrived, whereupon he hopped on an airplane and made his way to her lab. When I visited Zihlman’s lab several months ago, she showed me a thick photo album full of pictures of Gurche in a white lab coat actively participating in the dissections.

Zihlman recalls that Gurche was present for the dissections of several chimps, at least two gorillas, and an orangutan. He took “thousands” of photographs of his own, Zihlman recalls, and was particularly interested in measuring the thickness of the fat in the apes’ faces, which would provide him with educated guesses about what the faces of early hominins might have looked like. Gurche also made casts of the dissected faces, to capture the arrangement of muscles, and he once made a full body cast of a chimpanzee.

Adrie and Alfons Kennis, twin brother paleoartists from Arnhem in the Netherlands, had similar expert help when they were asked by National Geographic to reconstruct a female Neandertal nicknamed “Wilma.” The magazine’s science editor, James Shreeve, asked Steven Churchill, a paleoanthropologist at Duke University in Durham, North Carolina, to serve as science adviser on the project. “I was flown to Washington, D.C., to meet with the Kennis brothers,” Churchill says. “I put together a notebook for them on basic body proportions, the trunks, arms, and legs, and spent a day with them, Shreeve, and the other [editors].”

The project was particularly challenging, Churchill says, because although many male Neandertals had been reconstructed, there were very few models of females. After returning to Duke, Churchill exchanged e-mails with the Kennis brothers at least every 2 days, guiding them as the reconstruction took shape. 

The Paris studio of paleoartist Elisabeth Daynès (see photo) is also testimony to the close relationship between paleoartists and scientists. Her atelier is a regular stop for anthropologists visiting the City of Lights. (I have been a regular visitor myself for the past 10 years, an experience that was the original inspiration for my story in Science.) Just last week, William Jungers, a paleoanthropologist at Stony Brook University in New York, stopped by to discuss his ongoing collaboration with Daynès on how best to reconstuct the tiny Homo floresiensis, a.k.a. the Hobbit. “I’ve been working closely with Elisabeth on the hobbit, via e-mail and recently at the American Museum of Natural History in New York City,” Jungers told me recently. “I have also consulted with her on australopithecines and early Homo. She is very open to constructive criticism and suggestions based on real data from the fossil bones themselves.”

Daynès’s Web site includes several short videos of her interactions with scientists, such as her visit to Georgia to see David Lordkipanidze, director of the Dmanisi excavations, which have uncovered the oldest known hominins outside of Africa. In one particularly vivid scene, Daynès and Lordkipanidze sit and talk at the edge of the Dmanisi trenches with casts of the 1.8-million-year-old skulls on the ground before them.

—Michael Balter

PHOTO CREDIT: Copyright 2007 Photo P. Plailly Eurelios - Reconstruction Atelier Daynès Paris

In Victorian England, biologist Thomas Huxley battled to promote the theory of evolution so much that he was sometimes called "Darwin’s bulldog." Now, a new play follows Huxley throughout his fight, highlighting vicious debates with adversaries opposed to evolution, such as biologist Sir Richard Owen.

Written by zoologist and playwright Matthew Wilkinson, This View of Life debuted at the Darwin

darwinplayflyer150.jpgFestival in Cambridge last week. “[I got the idea] when I first became aware of Richard Owen and Thomas Huxley and that battle at the British Association meeting in 1860,” says Wilkinson, referring to the famous Oxford Evolution debate, for which influential men convened to deliberate over Darwin’s controversial ideas. “It seemed like there was great drama there, [with] Owen often painted as this archetypal villain, with Huxley as this sort of white knight.”

The play opens in 1893, when Huxley has just given what would be his last public debate on evolution. A ghostly memory of his daughter, who died as a young woman, takes Huxley through flashbacks of major events in his life, from meeting Charles Darwin to the 1860 debate. Huxley’s tussle with Owen over evolution and religion is a central theme. The rivalry was thought to stem from a fundamental disagreement on science, as well as from Owen’s jealousy of Huxley’s brilliant mind, explains Wilkinson. During the play, Owen fumes at Huxley:

“You are trying to eradicate God from society and humanity. … Would you have everyone believe that nature’s cruelty lies in us?”

Wilkinson tries to weave into the play the complex idea that progression in science and social reform in Victorian Britain provided fertile ground for evolutionary ideas to take root. Huxley himself was an advocate of social progress and gave many talks to Britain’s working classes on evolution. But once the concept of evolution became public property, it was twisted by many who used it to champion their own causes. The workers used the “survival of the fittest” idea as a metaphor by which they could improve their social situations. At the same time, the elite “Social Darwinists” were using ideas of natural selection to justify imperialism and the idea of ignoring the plight of the poor in society. Huxley laments this appropriation of Darwin’s work:

“Every faction is convinced that evolution is at the centre of their cause.”

After the death of his favorite daughter, Mady (Marion), Huxley was said to develop a very dark view of evolution, feeling that natural selection had robbed him of his daughter. But the play suggests that toward the end of his life, Huxley again saw beauty in evolution. “It’s the process by which we humans are united to the rest of life, our planet, and our universe,” says Wilkinson.

The playwright says he recognizes that Darwin’s view of nature, with the weakest being killed off, can be a brutal one. “On the other side, you can also look at all the cooperation that’s going on,” he says, such as in symbiotic relationships, in which two organisms rely on each other for survival. In one scene from the play, Huxley’s daughter gives an example of this, reminding her father how shrimp share their burrows with goby fish, who in return, warn the shrimp of approaching danger. Ending on this positive note, the play closes with an upbeat Huxley reading Darwin’s poignant and famous quote, from which the play’s title is derived:

“There is grandeur in this view of life, with its several powers, having been originally breathed into a few forms or into one; and that, whilst this planet has gone cycling on according to the fixed law of gravity, from so simple a beginning endless forms most beautiful and most wonderful have been, and are being, evolved.”

—Claire Thomas

Image: Ray Wilkinson

The Daily DarwinThe Daily Darwin, Friday July 10th - reports from the Darwin Festival by the Naked Scientists: We tie up the Darwin Festival with predictions on global warming and the future of the human species. Plus, we find out about cultural selection and how tricky it is putting together an exhibition on science and fine art!

Friday podcast (click to play)

Chris Smith and the rest of The Naked Scientists, that sartorially challenged group of researchers and science communicators, couldn't pass up attending the Darwin Festival given that it's in their home base of Cambridge. They have kindly allowed the Origins blog to rebroadcast their daily updates, hosted by Naked Scientist Diana O'Carroll, from the weeklong celebration. You can find additional free podcasts, science forums, and more on their Web site.

July 10, 2009

Inspiring Careers

One of our colleagues at ScienceCareers also has some thoughts on the Darwin Festival, noting how the naturalist and one of his greatest fans, David Attenborough, inspire people to love science—and even pursue it as a career.