THINK you can resist temptation? Then you are more likely to succumb, say Loran Nordgren and his colleagues at Northwestern University in Chicago.

The team took 53 smokers and promised them money if they did not light up while watching a clip of the film Coffee and Cigarettes . Each subject was given a cigarette and had to decide where to put it: in another room, on a desk, in

their hand or in their mouth. The closer the unsmoked cigarette, the more money they would gain.

Before this, the smokers had been given a bogus psychological test and then split at random into two groups: one was told they had “a high capacity for impulse control” and the other was labelled “low”. The latter group tended to put the cigarette far away, while those told they had

Bugs bare their magnetic bits

THE genetic code for tiny biological magnets called magnetosomes has been cracked.

The granules are produced by oxygen-hating bacteria and help them navigate, using the Earth’s magnetic field, towards deep, oxygen-poor regions of the ocean.

Tadashi Matsunaga at the Tokyo University of Agriculture and Technology in Japan and his colleagues singled out the genes by comparing well-known magnetic bacteria to a distantly related magnetic species. By identifying genes common to all species, they pinpointed those used for making magnetosomes (Genome Research, DOI: 10.1101/gr.088906.108).

The discovery may herald the production of synthetic nanomagnets, which could lead to improvements in MRI cancer scans and new ways to isolate medically useful molecules.

Why the highest peaks arealways at low latitudes

IS IT just a coincidence that all the world’s tallest

mountain ranges lie at low latitudes? Apparently not,

as it seems warmer climates enhance mountain growth.

Three things control how high a mountain range is

likely to grow: the strength of the underlying crust, the

magnitude of tectonic forces pushing upwards, and the

amount of erosion wearing the mountains down. All of

the world’s highest ranges have strong underlying crust,

but until now it wasn’t clear whether the world’s tallest

peaks were dominated by strong uplift or minimal erosion.

Using satellite images, David Egholm of Aarhus

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Lead thyself not into temptation good control risked holding it or putting it in their mouths. This bravado was their undoing, as the closer the cigarette, the more likely they were to smoke it.

Experiments without the bogus test showed the same effect. People confident that they could keep a snack for a week without eating it were more likely to crack than self-doubters, they say in a paper to appear in Psychological Science . The way to stay out of trouble, says Nordgren, is to avoid temptation.

University in Denmark and colleagues mapped all the

major mountain ranges between 60° north and 60° south,

plotting their land surface area against elevation. They

compared this with the average altitude of the snowline

and the latitude of each range. They also modelled the

effects of glacial erosion.

At low latitudes, the warmer climate tended to push

the snowline higher, and the mountains grew taller, they

found (Nature, DOI: 10.1038/nature08263). “Erosion

processes are more effective above the snowline where

glacial erosion dominates,” says Vivi Pedersen of Aarhus

University. Peaks are rarely more than 1500 metres

above the snowline, meaning that low-latitude ranges

like the Himalayas (pictured) have a head start over high-

latitude ranges because their snowline is much higher.

IF YOU must offend someone, wait until they’re lying down: a brain-scan study shows that people may contain their anger better when horizontal.

Seated subjects who heard personal insults showed brain activity linked to so-called approach motivation. “In this state, one might be more likely to attack,” says Eddie Harmon-Jones of Texas A&M University in College Station, who led the study. The activity disappeared when students took their insults lying down, though they still felt angry.

“Maybe in the reclining state you’re more likely to brood,” says Harmon-Jones. He worries that MRI studies which scan subjects as they are lying down could miss the neural signs of some emotions.

Insults are best taken lying down

12 | NewScientist | 15 August 2009