Ancient Human Footprints in Mexico?
Humans left their footprints on the shores of an ancient Mexican lake more than 25,000 years before people were thought to have colonized the Americas, according to a controversial new report.
Geochronologist Silvia Gonzalez of Liverpool John Moores University in the U.K. stumbled upon the prints in an abandoned quarry along what had once been a lake in the Valsequillo basin in central Mexico. “It felt like a thunderbolt,” she says.
Radiocarbon and electron spin resonance dating of nearby sediments place the prints—more than 150 apparently from humans, plus others from animals—at about 40,000 years old. Gonzalez believes the prints were made on a layer of fresh ash deposited by a nearby volcano, similar to the 3.5-million-year-old hominid prints in Laetoli, Tanzania. Some show clear outlines of toes, she says.
The findings have generally met with skepticism because there is little evidence that humans arrived in the Americas before 15,000 years ago. Although the dating may be accurate, “I have really serious reservations about whether these are footprints,” says geoarchaeologist Michael Waters of Texas A&M University in College Station. The impressions are probably marks from quarrying and erosion; nonetheless, he says, they're “worthy of further investigation.”
“I know we are in for a fight,” says Gonzalez. Last week, her team got a $372,000 U.K. government grant to do excavations at the site.
The Horse's Tale
DNA analysis has straightened out some of the tangled history of the North American horse and reduced its species from 50 to 2.
Because of rich fossil evidence and dramatic physical changes, horses are a textbook example of evolution. Equids originally arose in North America about 60 million years ago as small, five-toed animals. But their history on that continent is still being debated, especially for the period from about 3 million years ago to 10,000 years ago when they all went extinct. Some scientists have postulated that as many as 50 different horse species existed during that era.
To clarify the matter, Jaco Weinstock of the University of Oxford and colleagues examined mitochondrial DNA from the fossils of 53 horses from around the world ranging from 2000 to 50,000 years old. The evidence points to only two species, they report in PLoS Biology. One species spanned Eurasia and North America and continues today in the form of the modern horse.
The other species included the now-extinct stilt-legged horse, so-called because of its long, thin legs. The DNA analysis shows that despite its similarity to Asian asses, this species was a native product and not a transplant from Asia as some had thought.
R. Dale Guthrie, a paleontologist at the University of Alaska, Fairbanks, says the new study will help clear up the complicated and confusing history of horses. “It's taken something like mitochondrial DNA to answer the question,” he says.
Portrait of a Photon
It's darn hard to visualize a colorless particle of light, or any other subatomic particle, for that matter. Designer Jan-Henrik Andersen of the University of Michigan, Ann Arbor, has stepped in to help out. In consultation with physicists, he has developed a series of large-scale computer-generated images of subatomic particle energy and matter. The show, “Sized Matter—Perception of the Extreme Unseen,” is on view at the Fermi National Accelerator Laboratory in Batavia, Illinois, through 26 August.
I'm a Physicist, Not a Gym Teacher
A rose by any other name would smell as sweet, but a scientific society might be easier to identify if it adopts a simpler moniker. At least that's what physicists in the United States are hoping. Tired of being mistaken for gym teachers and physicians, leaders of the American Physical Society (APS) have proposed changing the organization's name to the American Physics Society.
Few people equate the word “physical” with physicists, explains Marvin Cohen, president of the 106-year-old society. “Many of us have stories of being confused with physical therapists and people involved with athletics,” he says. “The simple change to American Physics Society would suffice to show people what we do and that we're an organization of physicists.” APS is currently polling its more than 43,000 members to see if they agree.
Early feedback shows that most members welcome the change, Cohen says. But some say it's unnecessary. “I don't quite see how anyone who's literate can misinterpret” the current name, says physicist and writer David Mermin of Cornell University. Mermin also notes that a “physic” is a purgative, so “American Physics Society could be interpreted as an organization for the promotion of laxatives.”
Europe's biggest HIV research organization—the $49 million French National Agency for Research on AIDS and Viral Hepatitis (ANRS)—has a new director. Jean-François Delfraissy, a clinician at the forefront of HIV research and treatment since the early 1980s and most recently director of internal medicine at the Bicêtre Hospital in Paris, has authored more than 200 papers and played a key role in many clinical trials, including the first one to show the effectiveness of AZT against mother-to-child transmission of HIV. He has also promoted ANRS's recent expansion into hepatitis B and C research.
“He's an amiable person who doesn't seek the limelight,” says Joep Lange, past president of the International AIDS Society, who predicts that Delfraissy's accessible style will help foster international collaborations. Delfraissy succeeds Michel Kazatchkine, who in February became the French government's ambassador in the fight against AIDS.
Urologist Rolf-Hermann Ringert of the University of Göttingen in Germany has been barred from applying for grants from the German research agency DFG after the agency said he shared responsibility for “misrepresentations” in a 2000 paper that he co-authored with a former departmental former colleague.
A previous investigation by a university committee had found only the first author of the paper, Alexander Kugler, guilty of misconduct based on sloppy work and other irregularities in a paper that reported glowing results from a trial of a kidney cancer vaccine (Science, 22 November 2002, p. 1531). The DFG panel, however, decided that Ringert was responsible as lead author of the study and head of the department in which the research took place. The study, published in Nature Medicine, was retracted in September 2003.
The decision to impose an 8-year ban is not open to appeal, but Ringert says he is exploring his legal options.
Delayed payment. Stefanie Dimmeler can finally receive a $2 million prize from DFG after being cleared of a misconduct allegation. Dimmeler, a cardio-logist at Wolfgang Goethe University in Frankfurt am Main, did not accept the Leibniz Prize in March pending a university committee investigation into why she had published the same figure, with different captions, in two papers (Science, 11 March, p. 1559). Dimmeler said the mistake was an innocent one. Last week, DFG announced that the committee had concluded that the incident did not constitute misconduct. She will receive the money and prize citation immediately.
The percentage of women earning U.S. mathematics Ph.D.s has nearly doubled in the past 25 years. The all-time high of 333 doctorates awarded to women in 2003-04 represents one-third of the U.S. total (including citizens and noncitizens), according to a study appearing in the August issue of the Notices of the American Mathematical Society. That's up from 18% in 1980.
An increased interest in graduate school seems to be the driving force behind the growth, given that the percentage of women undergraduate math majors has remained flat at 45% for nearly a decade. And it undermines any argument that women aren't up to the challenge. “We would not be seeing this increase if women did not have the ability or the stamina to pursue math degrees,” says Ellen Kirkman, a professor at Wake Forest University in Winston-Salem, North Carolina, and lead author of the study.
More good news: Top-tier public universities are hiring more women with math Ph.D.s. Their slice of the job pie rose from 13% in 2000 to 23% in 2004.
Genomics entrepreneur J. Craig Venter has launched yet another ambitious pursuit: designing artificial bacteria. The leader of the corporate effort to sequence the human genome and captain of an around-the-world survey of marine microbes, Venter kicked off the enterprise last month by founding Synthetic Genomics Inc.
The Rockville, Maryland, company hopes to raise $30 million from private donors to build and commercialize organisms designed to make fuels such as hydrogen and ethanol. Other microbes would contain metabolic pathways useful for drug production and bioremediation. Part of the money will be used to support research at the nonprofit Venter Institute to develop the technology needed to make bacteria with humanmade genomes.