News in perspective

Upfront–

THE centuries-old idea that life was seeded from space was dusted off last week, thanks to a controversial study of a meteorite that struck Earth 40 years ago.

A team led by Zita Martins at Imperial College London claims it has found some of the fundamental chemical building blocks of our genetic code in the Murchison meteorite, which landed in Australia in 1969. In the mass of organic chemicals they isolated they found two ring-shaped carbon-containing molecules: uracil, a base that is essential for the creation of RNA, and xanthine, a close chemical

relative of the DNA base, guanine. Such chemicals have been

found in a number of meteorites, but no one was sure whether they were extraterrestrial or the result of contamination since the meteorite landed. To find out where the bases formed, Martins

and her colleagues measured the relative quantities of two different isotopes of carbon.

The lighter version, carbon-12, is present on Earth in large amounts. Carbon-13 is more common in clouds of interstellar gas, and large amounts of it usually indicate the material did not form on Earth. The ratio of carbon-13 to carbon-12 was unusually high in the two bases, leading the team to conclude that the materials probably did not form on Earth (Earth and Planetary Science Letters, vol 270, p 130).

“It boosts the idea that the origin of life on Earth may have had an important contribution from an extraterrestrial object,” says Martins.

It may be too early to conclude these bases formed beyond the Earth, says Sandra Pizzarello at Arizona State University, Tempe. Too many other chemicals were present in the samples to clearly distinguish the carbon ratio. “Analytically, it’s not convincing,” Pizzarello says. But she adds that the study “raises a very interesting question that was raised a long time ago, but I don’t think it solves it”.

WANT to win £10,000? Then prove that homeopathy works in proper clinical trials in which half the patients receive the treatment, half receive a placebo, and no one knows till the end who got what.

The challenge was issued on Monday by Edzard Ernst , professor of complementary medicine at the University of Exeter, UK, and science author Simon Singh, in the wake of what they call a smear campaign against them in response to their book Trick or Treatment , which

explores the scientific evidence behind complementary remedies. “We’re saying to homeopaths, ‘put up or shut up’,” says Singh.

The pair are not against complementary remedies. Of those examined in their book, 36 worked for particular conditions – such as St John’s wort for mild depression – but homeopathy was not among them.

Homeopaths seem in no hurry to take up the offer. “We have nothing to prove, and certainly not to people with closed minds,” says Steve Scrutton of the Alliance of Registered Homeopaths.

PLUTO – THE BATTLE GOES ONDefenders of “planet Pluto” have not been appeased by its latest name-change, and are marshalling support for a major scientific meeting devoted to debating its place in the solar system.

Last week, the International Astronomical Union (IAU) designated Pluto and its cousin Eris as “plutoids”. “It sounds like ‘haemorrhoids’,” says Alan Stern, who is chief scientist for NASA’s New Horizons mission to Pluto. He says that planetary scientists have

been left out of the IAU’s decision-making. Now these scientists will get the chance to present arguments for and against at “The Great Planet Debate” in August at Laurel, Maryland.

The IAU won’t be obliged to accept their conclusions. “The IAU has done what it could to come forward with a working definition,” says IAU general secretary Karel van der Hucht. “In the meantime, it’s a free world, anybody may organise meetings on the subject.”

HAPPY PIGS BREED BAD BUGS

“This boosts the idea that life on Earth may have had a contribution from space”

Animals reared in natural, outdoor conditions without nasty modern drugs yield healthier meat, right? Not necessarily.

Wondwossen Gebreyes and colleagues at Ohio State University in Columbus tested US pigs for antibodies – telltale signs of infection – to pathogens that can also affect humans. They found traces of Salmonella in 39 per cent of pigs raised in standard indoor pens and routinely given antibiotics, but in 54 per cent of organic pigs raised outdoors without the drugs (Foodborne

Pathogens and Disease, vol 5, p 199). This poses a dilemma, says Gebreyes:

giving pigs routine antibiotics favours antibiotic-resistant bacteria, but not giving them drugs means more animals carry Salmonella, which causes a million cases of food poisoning a year in the US alone.

They also found traces of the parasite Toxoplasma, carried by cats and other animals, in 1 per cent of conventional pigs but 7 per cent of free-range animals. The parasite can damage developing fetuses.

Worse, the US team found two organic pigs with signs of infection with Trichinella, a roundworm that can cause chronic disease and even kill when people eat undercooked pork. Trichinella is nearly eradicated in livestock in the the US and Europe, though it persists in wildlife. Finding it in two pigs of the 600 tested is 23 times its average frequency in US pigs.

“Does having an antibiotic-free and animal-friendly environment cause the re-emergence of historically significant pathogens?” Gebreyes asks. “That is an extremely important question for consumers, policy-makers and researchers.”

GET

TY

–Organic irony–

Space roots Prove it!

6 | NewScientist | 21 June 2008 www.newscientist.com