Tag: Scientist Smackdown

Scientist Smackdown: Did "Ardi" Change the Story of Human Evolution?

By Andrew Moseman | May 28, 2010 10:58 am

ArdiThe bones of our ancestors do not speak across time with ultimate clarity. The fossils with which scientists reconstruct our family tree are often fragments that offer hints and clues to where we came from. So it comes as no surprise when, as part of the flow of science, researchers offer counter-interpretations to even the most famous of finds.

That’s what happening to Ardi.

Last October Ardipithecus ramidus hit the main stage when, after 17 years of study, a large team led by paleoanthropologist Tim White published its work in the journal Science. The 4.4-million-year-old find shakes up our understanding of our own history, White said—primarily the story of how and when we learned to walk.

Ardi cast doubt on the widely accepted view that our ancestors became bipeds because they left the forest and entered a flatland savanna habitat that demanded it. But Ardi appeared to be a kind of hybrid, comfortable in the trees and on the ground. And, White said, analysis of the site where the fossil was found indicated that Ardi lived in a woodland habitat. If it’s true that early humans walked in the woods, then the “savanna hypothesis” would be swept away.

But not so fast. In today’s edition of Science, two teams of scientists respond (1, 2) with doubts about the story of Ardi.

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CATEGORIZED UNDER: Human Origins

Scientist Smackdown: Are Environmental Toxins a Huge Cancer Threat?

By Eliza Strickland | May 7, 2010 1:29 pm

presidential-cancer-panelYesterday, a government entity called the President’s Cancer Panel released an alarming report declaring that environmental toxins are causing “grievous harm” to Americans. The authors of the report (pdf) went on to say that while much more research needs to be done to determine the long-term effects of exposure, they believe that the “true burden of environmentally induced cancer has been grossly underestimated.”

But no sooner had they released the report than other cancer experts came forward to say that it wasn’t alarming, but rather alarmist.

First, the panel’s findings. In the 240-page report, the advisory panel noted that Americans are exposed to chemicals whose safety hasn’t yet been definitively established–like the chemical BPA that’s found in some everyday plastics, pesticides, and the substances found in industrial pollution. They write:

“With nearly 80,000 chemicals on the market in the United States, many of which are used by millions of Americans in their daily lives and are un- or understudied and largely unregulated, exposure to potential environmental carcinogens is widespread” [TIME].

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CATEGORIZED UNDER: Health & Medicine

Scientist Smackdown: Did a Nuclear Blast on Earth Create the Moon?

By Smriti Rao | February 4, 2010 9:38 am

moonHow on Earth did the moon come into being? If you subscribe to the latest theory, the moon was born out of a nuclear explosion on Earth that sent a chunk of mass flying from the planet’s core into orbit, where it finally became the moon. But cool as that sounds, some killjoy scientists are pooh-poohing the hypothesis, calling it “unnecessary,” “nonsensical,” and “not physically sensible.”

The standard theory of the moon’s origin holds that a giant space object, possibly an asteroid, banged into Earth and sent a large piece of the planet flying into space. That piece eventually became the moon. But the composition of the moon doesn’t seem to support this theory. Researchers say if an asteroid or some such object smashed away part of the Earth, the Moon ought to be composed of about 80 percent of that object’s constituent material and about 20 percent of the Earth’s. But the makeup of moon rock closely mirrors that of the Earth [Popular Science].

An alternate theory, known as the fission theory, suggests that the moon spun out of the rapidly spinning blob of molten rock that would later become Earth [Popular Science]. But no one has been able to explain what caused a huge chunk of earth to spin away and become the moon. Now, researchers Rob de Meijer and Wim van Westrenem have proposed in an online paper that centrifugal forces may have concentrated heavy, radioactive elements like uranium and thorium at the boundary between the Earth’s mantle and its core. Then, they propose, a massive nuclear explosion occurred at the edge of Earth’s core, flinging red-hot, liquid rock into space. The orbiting detritus gradually congealed into what is now our planet’s lone satellite [Discovery News].

Such “georeactors” have existed on Earth before, albeit on a smaller scale than these researchers propose. But de Meijer and van Westrenem have gotten little support for their hypothesis, and plenty of scorn.

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CATEGORIZED UNDER: Feature, Space

Scientist Smackdown: French Strike Back Against British G-Spot Study

By Andrew Moseman | January 29, 2010 11:55 am

GAs if soccer, wars of incredible length, and the relative worth of wine vs. beer didn’t account for enough disagreements between Britain and France, add another spat to the pile: whether or not the G-spot really exists.

A few weeks ago, a team of scientists from King’s College London joined the ongoing scientific fray by publishing a new study on the much-debated female erogenous zone. It was the biggest to date, involving 1,800 women – all of whom were pairs of identical or non-identical twins. If the G-spot did exist, it said, then genetically identical twins would have been expected to both report having one. However, no such pattern emerged [The Telegraph]. As a result of the study, coauthor Tim Spector said, the study “shows fairly conclusively that the idea of a G-spot is subjective.”

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CATEGORIZED UNDER: Health & Medicine, Mind & Brain

Scientist Smackdown: Is a Virus Really the Cause of Chronic Fatigue Syndrome?

By Andrew Moseman | January 6, 2010 5:18 pm

chronic-fatigue-virusAn estimated three in 1,000 people suffers from the mysterious affliction chronic fatigue syndrome. Those people were probably enthusiastic in October when a team of U.S. medical researchers released a study arguing that not only is the syndrome real (some doctors dismissed it as purely psychological “yuppie flu”), but also that they’d connected it to a specific virus. DISCOVER covered the hubbub after the paper came out in the journal Science.

But now, in a study in PLoS One, a British research team has cast doubt on the American team’s findings, saying there’s no conclusive link between the virus and chronic fatigue syndrome, which is also known as myalgic encephalomyelitis.

The U.S. team’s findings sounded robust when they came out. They found the murine leukaemia virus-related virus (XMRV) in blood samples of 68 of 101 patients diagnosed with chronic fatigue syndrome. Just eight out of 101 healthy “controls” drawn at random from the same parts of the US also tested positive, suggesting that XMRV played a key role in triggering the condition [The Independent]. When the scientists from Imperial and Kings colleges in London attempted to replicate these findings, however, they found nothing of the sort. Of the 186 people with the syndrome that this team tested, not one showed signs of XMRV, or of any related virus.

Study coauthor Myra McClure of the Imperial College also criticized the U.S. team and the journal Science for rushing the findings into print in October. “When you’ve got such a stunning result you want to be absolutely clear that you are 1,000 per cent right and there are things in that [previous study] I would not have done. I would have waited. I would have stalled a little” [The Independent], she said.

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CATEGORIZED UNDER: Health & Medicine

Scientist Smackdown: Are Unnecessary CT Scans Killing People?

By Andrew Moseman | December 16, 2009 3:12 pm

Ct-scan425Are CT scans putting thousands of people in unnecessary jeopardy for cancers and death? That was the suggestion by two new studies out this week, leaving radiologists scrambling to explain the true level of danger to worried patients.

A CT scan, also known as computed tomography, gives doctors a view inside the body, often eliminating the need for exploratory surgery. But CT scans involve a much higher radiation dose than conventional X-rays. A chest CT scan exposes the patient to more than 100 times the radiation dose of a typical chest X-ray [Reuters]. However, a study out of the University of California, San Francisco says, we might not have as good a handle on CT radiation as we thought. The researchers found that radiation differed greatly between machines, and some emitted 13 times more than others.

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CATEGORIZED UNDER: Health & Medicine

Scientist Smackdown: Are There Signs of Life in a Meteorite From Mars?

By Andrew Moseman | December 3, 2009 4:59 pm

NASAbiomorphs425It’s back. ALH 84001, the meteorite of Martian origin that NASA scientists claimed in 1996 contained evidence of life on Mars, has returned to the scene. This time, the team published a paper in the journal Geochimica et Cosmochimica Acta (the journal of the Geochemical and Meteoritic Society). And the scientists say they’re more confident than ever that the meteorite shows signs of martian life.

The NASA team of David McKay, Everett Gibson and Kathie Thomas-Keprta garnered widespread attention and even an announcement by President Bill Clinton when the 1996 paper came out. The NASA claim focused on nano-sized evidence: magnetite crystals embedded in the meteorite, which arrived here on Earth 13,000 years ago. Because some Earth bacteria secrete magnetite, McKay and his team argued that the mineral in the meteorite could be of biological origin, and the ‘biomorphs” in this image (which is from the new study) could be a fossilized colony of tiny bacteria. But the research was widely panned, and the NASA team making claims for life on Mars subsequently retreated [Discovery News].

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CATEGORIZED UNDER: Living World, Space

Scientist Smackdown: Are a Sprinter's Prostethic Legs an Unfair Advantage?

By Andrew Moseman | November 19, 2009 11:59 am

pistorius1If  you read this blog last week, you might have seen us cover a study suggesting that South African sprinter Oscar Pistorius ought to be allowed to compete in the same track and field events as everyone else because his prosthetic legs confer no advantage over a sprinter with biological legs. But if you saw a study cited by the Associated Press and many other publications yesterday, you might think that Pistorius would soon be banned from competitions, because his “blades” let him swing his legs far faster than even the world’s fastest man, Usain Bolt. So what the heck is going on?

The AP’s study isn’t actually a “study,” per se. Rather, what the Journal of Applied Physiology published was a point-counterpoint (pdf), now freely available for anyone to read. In in, Peter Weyand and Matthew Bundle argue that Pistorius’ prosthetics are a huge advantage, particularly in what matters most: how fast he can move his legs. Weyand and Bundle say that the lightweight blades allow Pistorius “to reposition his limbs 15.7 percent more rapidly than five of the most recent former world-record holders in the 100-meter dash” [AP].

There is, however, a counterpoint to this argument in the journal piece that yesterday’s news reports neglected, coauthored by Alena Grabowski of the MIT Media Lab (who led the research on Pistorius’ blades that 80beats covered last week). Her team has found that the limiting factor determining an athlete’s top speed was how hard the foot or prosthesis hit the ground. Their study showed this “ground force” was around 9% lower in the prosthetic limb versus the unaffected leg [The Guardian]. Grabowski’s research focused on professional runners with only one prosthetic leg.

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CATEGORIZED UNDER: Feature, Physics & Math, Technology

Scientist Smackdown: Can Nanoparticles Damage Human DNA?

By Brett Israel | November 9, 2009 5:52 pm

nanoparticles-web“Nanoparticles can cause DNA damage across a cellular barrier.” That’s the title of a paper published in Nature Nanotechnology that inspired a number of ominous news headlines (two examples: Nanoparticles ‘can damage DNA‘ and Nanoparticles can damage DNA at a distance: study). The stories that followed basically sang the same tune—that nanoparticles can damage our cells’ genetic material even from a distance (a relatively short distance of four cells away). However, experts are speaking up in response to the media hype, and argue that this study should have never been covered in the news. This particular study has little relevance to human exposure risks, experts say, and it is deeply flawed in other ways [ScienceNOW Daily News]. At least one expert called the study “meaningless,” however other scientists were more diplomatic and have pointed to a number of interesting questions the study raises that are worth pursuing.

In the study, researchers exposed a thin “barrier” of four layers of cancer cells to cobalt-chromium ions or particles. Cells close to the nanoparticles experienced signs of mitochondrial damage. But even cells on the other side of the barrier suffered some DNA damage, the team found, despite the fact that there was no evidence that the metals themselves moved through the cells to the other side of the barrier [ScienceNOW Daily News]. Interesting indeed, but experts are pointing out that this set-up is not entirely relevant to humans, or any living organism for that matter.

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CATEGORIZED UNDER: Feature, Physics & Math, Technology

Scientist Smackdown: Did a Comet Explode Over Prehistoric North America?

By Brett Israel | October 19, 2009 7:00 am

comet-nasa-webAccording to a theory proposed in 2007, the explosion of a comet over North America killed off the Clovis people and many of the continent’s largest mammals nearly 13,000 years ago. Not so fast, says a new study published in the Proceedings of the National Academy of Sciences, fueling a WWE-style stare down between the opposing camps.

The new report explains that archaeologists have examined sediments at seven Clovis-age sites across the United States, and found that the concentration of magnetic debris was insufficient to confirm an extraterrestrial impact at that time [Nature News]. The original theory’s evidence came from magnetic microspherules, or cosmic debris, discovered in sediments at 25 locations. However, one of the new study’s authors, Todd Surovell, said that even after 18 months of sedimentary analysis and hundreds of hours peering into a microscope, he could find no evidence of microspherules to support the the exploding comet theory. Snap.

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CATEGORIZED UNDER: Environment, Human Origins
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