Vector without Virus Off Target
To deliver genes into cells, scientists rely on engineered viruses, but these germs often provoke immune responses and make them potentially lethal. New silica nanoparticles with organic components may prove effective nonviral DNA carriers. Chemists at the University at Buffalo found that the electric charge on these nanoparticles held and compacted the DNA, protecting it from enzymatic digestion in cells. The organic components also render normally rigid silica nanoparti-cles more flexible and capable of releasing encapsulated biomolecules and might make the nanoparticles safely biodegradable as well. Nanoparticles with the gene for green fluorescent protein penetrated cultured monkey kidney cells, delivered the DNA once inside and successfully modified their genes. The investigators now are using the technique in mice to carry genes into nerve cells. Their report appeared in the January 11 issue of Proceedings of the National Academy of Sciences USA. — Charles Q. Choi
The drug industry has heralded targeted cancer therapies, which attack a specific protein identified through molecular analysis, as the next wave in treatment. This strategy received a setback last December, when the European drugmaker AstraZen-eca reported that its targeted therapy, Iressa (gefitinib), shrank tumors but was no more effective than a placebo at extending the lives of patients with lung cancer. In light of this study, which included 1,700 people, AstraZeneca withdrew its application for approval in Europe. The company's hopes of ever achieving blockbuster status for Ir-essa have now all but faded. The drug's future in the U.S., which approved it in 2003, is uncertain as the FDA deliberates whether to pull it off the market. Many patients have moved to Tarceva, a targeted treatment from Genentech and OSI Pharmaceuticals that has improved patient survival. Astra-Zeneca plans to continue studies of Iressa for other types of cancer. — Gary Stix
The secret to universal broadband Internet access could be right above your head. Power lines can carry broadband in the form of high-frequency electrical signals, and some European and U.S. utilities are already testing such systems. The problem is that forks in the electrical grid reflect broadband signals and thereby degrade transmission. Pennsylvania
State University researchers simulated what would happen if lines were synched up with transformers and other electrical loads to minimize reflection. They found that signals should flow fast enough to give homes data-transfer rates of hundreds of megabits per second, tens of times faster than DSL or cable, they told the IEEE Consumer Communications & Networking Conference on January 5. The cost-effectiveness of broadband power lines remains to be seen, says lead researcher Mohsen Kavehrad, as it would interfere with some radio signals. —JR Minkel
KC & the Sunshine Cow
Breeding cows for beef is often slow because the qualities of a top-grade cut, marbling and tenderness, are unknown until after a cow is slaughtered. That may change soon thanks to a newborn calf born healthy to the first cow cloned from a beef carcass. The mother, KC, is named after the kidney cell from which she was cloned. Her calf, Sunshine, was born naturally in mid-December, lively and fit at 72 pounds. The technology
A long-standing mystery in marine biology is whether whales suffer from decompression sickness, a.k.a. the bends, after rapidly rising from the ocean depths. Biologists worked on the assumption the creatures were immune, but recent reports of beaked whales suffering acute bendslike symptoms after military sonar exposure raised the question anew. Now researchers from the Woods Hole Oceanographic Institution have examined 16 sperm whale skeletons collected since 1870 and found pockmarks and erosion in the bones of adult whales. The damage worsened with age and is consistent with the kind of bone injury that deep-sea divers suf-
used to generate KC could also clone an animal from a freshly processed cut of beef, says Steven Stice, an animal scientist at the University of Georgia. Although cloned animals cannot legally enter the food chain, their offspring might soon: later this year the Food and Drug Administration is expected to weigh in on the safety of eating such animals, which an earlier FDA draft deemed safe. — Charles Q. Choi
fer. If the bends is the culprit, whales have likely evolved behaviors to avoid the malady, such as gradual surfacing, says study co-author Michael Moore, and stressors such as sonar could sicken whales if they disrupt those behaviors. The study surfaced in the December 24, 2004, Science. —JR Minkel news
■ Wet sand or soft clay is how the Huygens spacecraft portrayed Titan's surface when it successfully landed on the Saturnian moon on January 14.
■ Retinal recordings explain why swordfish have a heating organ in the muscle to keep their eyes 10 to 15 degrees warmer than ambient temperatures: the warmth enables the fish to process visual information
10 times faster, improving the ability to spot prey.
Current Biology, January 11
■ Regenerating hair cells of the inner ear, and thus restoring hearing, could be possible: hair cells proliferated in mice engineered to lack the Rb1 gene, which helps to regulate cell division.
Science Express Online, January 14
■ Rats can distinguish spoken Dutch from Japanese. This ability, however, probably is a by-product of general perceptual facilities rather than an indication of linguistic capacity.
Journal of Experimental Psychology: Animal Behavior Processes, January
The Fossil Fallacy
Creationists' demand for fossils that represent "missing links" reveals a deep misunderstanding of science By MICHAEL SHERMER
Nineteenth-century English social scientist Herbert Spencer made this prescient observation: "Those who cavalierly reject the Theory of Evolution, as not adequately supported by facts, seem quite to forget that their own theory is supported by no facts at all." Well over a century later nothing has changed. When I debate creationists, they present not one fact in favor of creation and instead demand "just one transitional fossil" that proves evolution. When I do offer evidence (for example, Ambulocetus natans, a transitional fossil between ancient land mammals and modern whales), they respond that there are now two gaps in the fossil record.
This is a clever debate retort, but it reveals a profound error that I call the Fossil Fallacy: the belief that a "single fossil"— one bit of data—constitutes proof of a multifarious process or historical sequence. In fact, proof is derived through a convergence of evidence from numerous lines of inquiry—multiple, independent inductions, all of which point to an unmistakable conclusion.
We know evolution happened not because of transitional fossils such as A. natans but because of the convergence of evidence from such diverse fields as geology, paleontology, bioge-ography, comparative anatomy and physiology, molecular biology, genetics, and many more. No single discovery from any of these fields denotes proof of evolution, but together they reveal that life evolved in a certain sequence by a particular process.
One of the finest compilations of evolutionary data and theory since Charles Darwin's On the Origin of Species is Richard Dawkins's magnum opus, The Ancestor's Tale: A Pilgrimage to the Dawn of Evolution (Houghton Mifflin, 2004)—688 pages of convergent science recounted with literary elegance. Dawkins traces numerous transitional fossils (what he calls "concestors," the last common ancestor shared by a set of species) from Homo sapiens back four billion years to the origin of heredity and the emergence of evolution. No single concestor proves that evolution happened, but together they reveal a majestic story of process over time.
Consider the tale of the dog. With so many breeds of dogs popular for so many thousands of years, one would think there
We know evolution happened because of a convergence of evidence.
would be an abundance of transitional fossils providing paleontologists with copious data from which to reconstruct their evolutionary ancestry. In fact, according to Jennifer A. Leonard, an evolutionary biologist then at the Smithsonian Institution's National Museum of Natural History, "the fossil record from wolves to dogs is pretty sparse." Then how do we know whence dogs evolved? In the November 22, 2002, Science, Leonard and her colleagues report that mitochondrial DNA (mtDNA) data from early dog remains "strongly support the hypothesis that ancient American and Eurasian domestic dogs share a common origin from Old World gray wolves."
In the same issue, molecular biologist Peter Savolainen of the Royal Institute of Technology in Stockholm and his colleagues note that even though the fossil record is problematic, their study of mtDNA sequence variation among 654 domestic dogs from around the world "points to an origin of the domestic dog in East Asia" about 15,000 years before the present from a single gene pool of wolves.
Finally, anthropologist Brian Hare of Harvard University and his colleagues describe in this same issue the results of a study showing that domestic dogs are more skillful than wolves at using human signals to indicate the location of hidden food. Yet "dogs and wolves do not perform differently in a nonsocial memory task, ruling out the possibility that dogs outperform wolves in all human-guided tasks," they write. Therefore, "dogs' social-communicative skills with humans were acquired during the process of domestication."
No single fossil proves that dogs came from wolves, but archaeological, morphological, genetic and behavioral "fossils" converge to reveal the concestor of all dogs to be the East Asian wolf. The tale of human evolution is divulged in a similar manner (although here we do have an abundance of fossils), as it is for all concestors in the history of life. We know evolution happened because innumerable bits of data from myriad fields of science conjoin to paint a rich portrait of life's pilgrimage. ®
Michael Shermer is publisher of Skeptic (www.skeptic. com) and author of The Science of Good and Evil.
Seven years ago Michael Mann introduced a graph that became an iconic symbol of humanity's contribution to global warming. He has been defending his science ever since By DAVID APPELL
Michael Mann knows his students and his subject. The topic of the graduate seminar: El Niño and radiative forcing. The beer he will be serving: Corona, "because I'm going to be talking about tropical climate." Not surprisingly, attendance is high.
Mann is most famously known for the "hockey stick," a plot of the past millennium's temperature that shows the drastic influence of humans in the 20th cen-
MICHAEL MANN: DETECTING PAST CLIMATE
■ Started out as a physicist in theoretical condensed matter but switched to climatology for the big picture.
■ With nine other scientists, he blogs at www.realclimate.org
■ On whether global warming is really a problem: "To some extent, that's a value judgment"—that is, whether society prefers economic growth or the environment.
fil tury. Specifically, temperature remains essentially flat until about 1900, then shoots up, like the upturned blade of a hockey stick. The work was also the first to add error bars to the historical temperatures and allow for regional reconstructions of temperature.
That stick has become a focal point in the controversy surrounding climate change and what to do about it. Proponents see it as a clear indicator that humans are warming the globe; skeptics argue that the climate is undergoing a natural fluctuation not unlike those in eras past. But Mann has not been deterred by the attacks. "If we allowed that sort of thing to stop us from progressing in science, that would be a very frightening world," says the 39-year-old climatologist in his University of Virginia office overlooking the hills of Monticello, the home of Thomas Jefferson.
To construct the hockey-stick plot, Mann, Raymond S. Bradley of the University of Massachusetts Amherst and Malcolm K. Hughes of the University of Arizona analyzed paleoclimatic data sets such as those from tree rings, ice cores and coral, joining historical data with thermometer readings from the recent past. In 1998 they obtained a "reconstruction" of Northern Hemisphere temperatures going back 600 years; by the next year they had extended their analysis to the past 1,000 years. In 2003 Mann and Philip D. Jones of the University of East Anglia in England used a different method to extend results back 2,000 years.
In each case, the outcome was clear: global mean temperature began to rise dramatically in the early 20th century. That rise coincided with the unprecedented release of carbon dioxide and other heat-trapping gases into the earth's atmosphere, leading to the conclusion that industrial activity was boosting the world's mean temperature. Other researchers subsequently confirmed the plot.
The work of Mann and his colleagues achieved special prominence in 2001. That is when the Intergovernmental Panel on Climate Change (IPCC), an international body of climate experts, placed the hockey-stick chart in the Summary for Policymakers section of the panel's Third Assessment Report. (Mann also co-authored one of the chapters in the report.) It thereby elevated the hockey stick to iconic status—as well as making it a bull's-eye. A community skeptical of human-induced warming argued that Mann's data points were too sparse to constitute a true picture, or that his raw data were numerically suspicious, or that they could not reproduce his results with the data he had used. Take down Mann, it seemed, and the rest of the IPCC's conclusions about anthropogenic climate change would follow.
That led to "unjustified attack after unjustified attack," complains climatologist Gavin A. Schmidt of the NASA God-dard Institute for Space Studies. Although questions in the field abound about how, for example, tree-ring data are compiled, many of those attacking Mann's work, Schmidt claims, have had a priori opinions that the work must be wrong. "Most scientists would have left the field long ago, but Mike is fighting back with a tenacity I find admirable," Schmidt says. One of Mann's more public punch backs took place in July 2003, when he defended his views before a congressional committee led by Senator James M. Inhofe of Oklahoma, who has called global warming a "hoax." "I left that meeting having demonstrated what the mainstream views on climate science are," Mann asserts.
More recently, Mann battled back in a 2004 corrigendum in the journal Nature, in which he clarified the presentation of his data. He has also shown how errors on the part of his attackers led to their specific results. For instance, skeptics often cite the Little Ice Age and Medieval Warming Period as pieces of evidence not reflected in the hockey stick, yet these extremes are examples of regional, not global, phenomena. "From an intellectual point of view, these contrarians are pathetic, because there's no scientific validity to their arguments whatsoever," Mann says. "But they're very skilled at deducing what sorts of disingenuous arguments and untruths are likely to be believable to the public that doesn't know better."
Mann thinks that the attacks will continue, because many skeptics, such as the Greening Earth Society and the Tech Central Station Web site, obtain funds from petroleum interests. "As long as they think it works and they've got unlimited money to perpetuate their disinformation campaign," Mann believes, "I imagine it will go on, just as it went on for years and years with tobacco until it was no longer tenable—in fact, it
"HOCKEY STICK" graph shows a 20th-century upturn in temperature in the Northern Hemisphere. The error range is greater in the past because the data are sparser.
"HOCKEY STICK" graph shows a 20th-century upturn in temperature in the Northern Hemisphere. The error range is greater in the past because the data are sparser.
became perjurable to get up in a public forum and claim that there was no science" behind the health hazards of smoking.
As part of his hockey-stick defense, Mann co-founded with Schmidt a Weblog called RealClimate (www.realclimate.org). Started in December 2004, the site has nine active scientists, who have attracted the attention of the blog cognoscenti for their writings, including critiques of Michael Crichton's State of Fear, a novel that uses charts and references to argue against anthropogenic warming. The blog is not a bypass of the ordinary channels of scientific communication, Mann explains, but "a resource where the public can go to see what actual scientists working in the field have to say about the latest issues."
The most challenging aspect today, Mann thinks, is predicting regional disruptions, because people are unlikely to take climate change seriously until they see how it operates in their backyard. In that regard, he has turned his attention to El Niño, a warming of eastern tropical Pacific waters that affects global weather. In discussing the issue with his students over their Coronas, Mann notes that comparisons with the paleoclimatic record seem to confirm a mechanism proposed by other researchers. Specifically, radiative forcings—volcanic eruptions and solar changes, for instance— do in fact alter El Niño, turning it into more of a La Niña state, with colder sea-surface temperatures. Understanding how El Niño has changed with past radiative forcings is a first step to understanding how it will change in an increasingly greenhouse-gassed world.
Mann remains somewhat mum on whether the U.S. should join the Kyoto Treaty, an international agreement to limit fossil-fuel emissions: "It's hard enough predicting the climate. I don't pretend to be able to predict the behavior of politicians." He sees the Kyoto accord as an initial step that is unlikely to curtail emissions all that much, but it will at least set in motion a process that can be built on with other treaties.
Such efforts are essential, because the blade of Mann's hockey stick will get longer. He notes that "we're already committed to 50 to 100 years of warming and several centuries of sea-level rise, simply from the amount of greenhouse gases we've already put in the atmosphere." The solution to global warming, he observes, "is going to be finding an appropriate set of constraints on fossil-fuel emissions that allow us to slow the rate of change down to a level we can adapt to." ®
David Appell is based in Newmarket, N.H.
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