Prised from dead hands PACKING heat may backfire. People who carry guns are far more likely to get shot than those who are unarmed, a study of shooting victims in Philadelphia, Pennsylvania, has found. It would be impractical – not to say unethical – to randomly assign volunteers to carry a gun or not and see what happens. So Charles Branas’s team at the University of Pennsylvania analysed 677 shootings over two-and-a-half years to discover whether victims were carrying at the time, and compared them to other Philly residents of similar age, sex and ethnicity. The team also accounted for further potentially confounding differences, such as the socioeconomic status of their neighbourhood. Overall, people who carried guns were 4.5 times as likely to be shot
and 4.2 times as likely to get killed compared with unarmed citizens. When Branas’s team looked at shootings in which victims had a chance to defend themselves, their odds of getting shot were even higher (American Journal of Public Health, DOI: 10.2105/AJPH.2008.143099) While people who think they are at risk of getting shot may also be more likely to carry firearms, Branas speculates that guns may give a sense of empowerment that causes carriers to overreact, or encourages them to visit dangerous neighbourhoods. Supporters of the Second Amendment shouldn’t worry that the right to bear arms is under threat, however. “We don’t have an answer as to whether guns are protective or perilous,” Branas says. “This study is a beginning.”
–Protector or peril?–
Face gene facts COMPANIES that offer analyses of future health risks based on basic genetic tests should explain the limitations of their predictions more clearly, says genomics pioneer Craig Venter. He and four colleagues have proposed guidelines for the industry after assessing the results of scans of their personal genomes, as provided by the Californian firms 23andMe and Navigenics. They found that for each set of results, the companies identified genetic variants consistently at least 99.7 per cent of the time, but diverged on their assessment of the associated health risks (Nature, vol 461, p 724). For four common diseases, the
“Firms identified genetic variants consistently, but diverged on assessments of the linked health risks” companies agreed for all five individuals on whether each had a reduced, average, or increased risk. But for seven other conditions, they came up with different 6 | NewScientist | 10 October 2009
answers for at least two of the group. The predictions were particularly varied for the skin disease psoriasis: in Venter’s case, 23andMe put his risk at more than four times a typical person’s, whereas Navigenics said it was just 25 per cent above average. Such differences arise largely because they look at different collections of genetic markers. Venter, who heads his own genetics institute in San Diego, California, says firms should agree on core markers with strong effects for each disease, and tell customers what proportion of their genetic risk these account for. “We do have estimates, and we will consider how best to communicate them to our customers,” says Andro Hsu of 23andMe. Geneticists still know little about how differences in people’s DNA affect health, says Venter: “My whole genome is out there and it can’t give me much more information than the personal genomics companies.” What’s needed, he says, is the collection of detailed health data from thousands of people who have had their genomes fully sequenced.
Bill feels the heat THE US will cut its greenhouse gas emissions by 20 per cent by 2020. That is the idea, at least. After weeks of delay, a climate-change bill has finally been introduced into the Senate. It will face stiff opposition. Most Republicans are almost certain to vote against the bill, citing concern for US industry. Even some with a track record of action on climate change are opposed: former presidential candidate John McCain told Reuters that he
would “never, never, never” vote for the bill. Dissent also comes from Democrats representing coal-rich or farming states. Debates are scheduled for later this month, leaving little decision time before the crucial climate summit in Copenhagen, Denmark, in December. “It is very important to get a vote before December,” says Jennifer Morgan, climate and energy programme director at the World Resources Institute in Washington DC. “It would give credibility to the US delegation at the talks.”
Saturn’s biggest ring was hiding A RING of space debris 2.4 million kilometres from edge to edge should be hard to miss, yes? Apparently not, since one this thick has been spotted orbiting Saturn. It’s the biggest ring found in our solar system so far. The discovery seems to confirm the idea that the leading hemisphere of Saturn’s two-toned moon Iapetus is much darker than its trailing side because it has been coated with dust from collisions between debris and Saturn’s outer moons.
Anne Verbiscer of the University of Virginia in Charlottesville found the ring when she trained the Spitzer Space Telescope on a patch of sky just inside the orbit of Saturn’s far-flung moon Phoebe. The infrared telescope found a telltale glow indicating the presence of a tenuous ring of dust that had absorbed sunlight and reradiated it as heat (Nature, DOI: 10.1038/nature08515). It would have been difficult to detect using visible light because it is so diffuse.