Monday, March 1, 2010

Turtle: For some, it's the other white meat
By John Platt

American freshwater turtles are being harvested at an unsustainable rate to feed the voracious appetite for turtle meat in Asia, warns the Center for Biological Diversity in Tucson, Arizona.

Earlier this month, the organization petitioned eight U.S. states (Arkansas , Iowa, Kentucky, Louisiana, Missouri, Ohio, South Carolina, and Tennessee) to ban turtle hunting in all public and private waters. Meanwhile, Florida's Fish and Wildlife Conservation Commission has proposed its own ban, and will present a draft of the rules at a Commission meeting next month. The Commission recently estimated that 3,000 pounds of softshell turtles are flown out of Tampa International Airport every week, enroute to food markets in Asia.

According to data collected by the CBD, turtle harvesting has increased dramatically over the past decade. Harvesters in Iowa, for example, collected 235,000 pounds of turtles in 2007, up more than 800 percent from the 29,000 pounds collected in 1987. In Arkansas, nearly 600,000 turtles were collected between 2004 and 2006.

While some freshwater species are endangered in the U.S., protection is difficult since many species look similar to untrained eyes. Alligator snapping turtles (Macrochelys temmickii), which are protected by state law in Iowa and Illinois, look almost exactly like common snapping turtles (Chelydra serpentina), which are not endangered.

So why is turtle collection from the wild such a problem? "Because freshwater turtles are long lived (some may reach 150 years of age), breed late in life, and have low reproductive and survival rates, they are highly vulnerable to overharvest," the CBD said in a statement.

Would banning the wild-turtle trade help? Supporters of such a move point to Texas as an example. The state outlawed most turtle harvesting two years ago, and as a result saw Asian exports through Dallas/Fort Worth International Airport drop from 122,610 turtles in 2004 to just 8,882 in 2007, according to U.S. Fish & Wildlife Service numbers cited by the Dallas Morning News. Commercial harvesting of three turtle species from private waters is still allowed under Texas law.
New Fossil Shows How the Turtle Got Its Shell
Odontochelys semitestacea, the oldest turtle fossil yet, has a fully formed lower shell, or plastron, but lacks a fully formed upper shell
By Kate Wong

Vertebrate animals come in all shapes and sizes. But some have evolved truly bizarre forms. With beaks instead of teeth and shells formed by the ribs and other bits, turtles surely rank among the strangest of our backboned brethren. Indeed, paleontologists have long puzzled over how turtles acquired their odd traits and who their closest relatives are.

Previously, much of what researchers knew about turtle origins derived from fossils of Proganochelys from Germany. Based on that creature, with its heavily built shell and spiked plates covering the neck and tail, researchers had proposed that turtles were kissing cousins of a group of extinct armored reptiles known as pareiasaurs. They also suggested that the first turtles lived on land, where a shield is a useful defense for a slow-footed creature. Proganochelys furnished no clues to how the turtle shell evolved, however, because its own carapace is fully formed.

A newfound fossil from southwestern China’s Guizhou Province paints a rather different picture of the origin of turtles and illuminates how their trademark armature took shape. Dating back to 220 million years ago, this transitional creature, named Odontochelys semitestacea (“half-shelled turtle with teeth”), is the oldest and most primitive turtle on record. Researchers led by Chun Li of the Chinese Academy of Sciences in Beijing describe the fossil in the November 27, 2008, issue of Nature.

Odontochelys possesses a plastron—the flat, lower half of the shell that protects the animal’s soft belly—but lacks the domed upper half. What this suggests, Li and his colleagues say, is that the shell evolved from the bottom up. In addition, the deposits that yielded the fossil indicate that this animal lived in a marine environment. If so, the plastron would have shielded the turtle’s underside from predators approaching from below.

Odontochelys also lacks osteoderms, bony plates in the skin that form the armor of reptiles such as crocodiles and dinosaurs. Some specialists had proposed that the turtle’s shell began as rows of osteoderms that gradually, over millions of years, fused to form a carapace. In fact, last October researchers writing in the Proceedings of the Royal Society B reported on a 210-million-year-old turtle fossil from New Mexico believed to support exactly that hypothesis.

But critics have countered that findings from turtle embryology hinted that the backbones and ribs morphed to make a shell. Odontochelys bolsters the theory that ribs flattened and spread to form the top of the shell.

The absence of osteoderms in Odontochelys also challenges the idea that turtles are closely related to pareiasaurs. Taken together with molecular data, the new evidence aligns the shelled vertebrates with another group of reptiles, the diapsids.

Some aspects of the discovery team’s interpretation of Odontochelys have alternative explanations, however. In a commentary accompanying the Nature paper, paleontologists Robert Reisz and Jason Head of the University of Toronto Mississauga argue that the animal did have an upper shell, just one that had not fully ossified. If correct, their supposition would suggest that the form of this animal’s shell, rather than being a primitive intermediate, is a specialized adaptation. It turns out that aquatic turtles often have smaller, more delicate upper shells compared with their landlubber counterparts, as seen in sea turtles and snapping turtles.

Thus, rather than showing that turtles evolved in the water, Reisz and Head contend, Odontochelys may signal an early invasion of the water by turtles that originated on terra firma. “The morphology of Odontochelys suggests that this story is more complex and more interesting than suggested” by Li and his co-authors, Reisz remarks. “We feel that Odontochelys is not the final answer; it is instead one more piece in the fascinating puzzle of turtle origins.”
Smile! It Could Make You Happier
Making an emotional face--or suppressing one--influences your feelings
By Melinda Wenner

FACIAL FEELINGS: There might be a feedback loop between our faces and our feelings, new research on botox recipients suggests.

We smile because we are happy, and we frown because we are sad. But does the causal arrow point in the other direction, too? A spate of recent studies of botox recipients and others suggests that our emotions are reinforced—perhaps even driven—by their corresponding facial expressions.

Charles Darwin first posed the idea that emotional responses influence our feelings in 1872. “The free expression by outward signs of an emotion intensi­fies it,” he wrote. The esteemed 19th-cen­tury psychologist William James went so far as to assert that if a person does not express an emotion, he has not felt it at all. Although few scientists would agree with such a statement today, there is evidence that emotions in­volve more than just the brain. The face, in particular, appears to play a big role.

This February psychologists at the University of Cardiff in Wales found that people whose ability to frown is comp­romised by cosmetic botox inject­ions are happier, on average, than people who can frown. The researchers administered an anxiety and depression questionnaire to 25 females, half of whom had received frown-inhibiting botox injections. The botox recipients reported feeling happier and less anxious in general; more important, they did not report feeling any more attractive, which suggests that the emotional effects were not driven by a psychological boost that could come from the treatment’s cosmetic nature.

“It would appear that the way we feel emotions isn’t just restricted to our brain—there are parts of our bodies that help and reinforce the feelings we’re having,” says Michael Lewis, a co-author of the study. “It’s like a feedback loop.” In a related study from March, scientists at the Technical University of Munich in Germany scanned botox recipients with fMRI machines while asking them to mimic angry faces. They found that the botox subjects had much lower activity in the brain circuits involved in emotional processing and responses—in the amygdala, hypothal­amus and parts of the brain stem—as compared with con­trols who had not received treatment.

The concept works the opposite way, too—enhancing emotions rather than suppressing them. People who frown during an unpleasant procedure report feeling more pain than those who do not, according to a study published in May 2008 in the Journal of Pain. Researchers applied heat to the forearms of 29 participants, who were asked to either make unhappy, neutral or relaxed faces during the procedure. Those who exhibited negative expressions reported being in more pain than the other two groups. Lewis, who was not involved in that study, says he plans to study the effect that botox injections have on pain perception. “It’s possible that people may feel less pain if they’re unable to express it,” he says.

But we have all heard that it is bad to repress our feelings—so what happens if a person intentionally suppresses his or her negative emotions on an ongoing basis? Work by psychologist Judith Grob of the University of Groningen in the Netherlands suggests that this suppressed negativity may “leak” into other realms of a person’s life. In a series of studies she performed for her Ph.D. thesis and has submit­ted for publication, she asked sub­jects to look at disgusting images while hiding their emotions or while holding pens in their mouths in such a way that prevented them from frowning. A third group could react as they pleased.

As expected, the subjects in both groups that did not express their emotions reported feeling less disgusted afterward than control subjects. Then she gave the subjects a series of cognitive tasks that included fill-in-the-blank exercises. She found that subjects who had repressed their emotions performed poorly on memory tasks and completed the word tasks to produce more negative words—they completed “gr_ss” as “gross” rather than “grass,” for instance—as compared with controls. “People who tend to do this regularly might start to see the world in a more negative light,” Grob says. “When the face doesn’t aid in expressing the emotion, the emotion seeks other channels to express itself through.