10 March 2012 | NewScientist | 5

disrupting animal behaviour.Bärbel Hönisch of Columbia

University in Palisades, New York, and colleagues used the chemical record preserved in rocks to gauge previous acidification events. The best match for today was the Palaeocene-Eocene thermal maximum of 55 million years ago, when a huge greenhouse gas release caused rapid global warming, ocean acidification and mass extinctions (Science, DOI: 10.1126/science.1208277).

But even then, it took 3000 years for ocean pH to drop by 0.5. “That is an order of magnitude slower than today,” Hönisch says.

Alzheimer’s hopeAT LAST, some good news for people with Alzheimer’s. Those in the later stages of the disease can benefit from taking donepezil and memantine, which delay the onset of more severe symptoms.

Earlier evidence suggested that only people with mild to moderate symptoms benefited from the drugs, so doctors often halt treatment in the later stages of the disease.

Now, Robert Howard at King’s College London and colleagues have shown that people with advanced Alzheimer’s benefit too. They gave either one or both of the drugs to 285 people with Alzheimer’s, who were already taking donepezil but had reached a point where they would normally stop.

The drugs delayed decline by four months in those who continued with one or both for the following year, compared with those on a placebo (The New England Journal of Medicine, vol 366, p 893). “It makes a huge difference – between being able and not able to feed yourself, for example,” says Clive Ballard, chairman of the UK Alzheimer’s Society.

As a bonus, a cheaper generic version of donepezil was launched last month.

Sprinting robo-catYOU can run, but you won’t escape… A robot named Cheetah has broken the speed record for four-legged robots by reaching almost 30 kilometres an hour (see the video at bit.ly/robocheet).

Much like a real cheetah, the robot uses a short, hopping gait at low speeds before increasing its stride and pace by flexing and unflexing its back with each step.

Cheetah is being developed by Boston Dynamics of Waltham, Massachusetts, with funding from the US Defense Advanced Research Projects Agency. The

current version of the robot is powered by a hydraulic pump and has only been tested on a treadmill, where it is tethered to ensure it stays on track. The firm aims to test a free-running prototype this year.

Last year Boston Dynamics unveiled BigDog, designed as a military pack mule, and the humanoid PETMAN, which runs on two legs and can do press-ups.

“Much like a real cheetah, it boosts its stride and pace by flexing and unflexing its back with each step”

TALK about unwanted guests. Visitors to Antarctica are unwittingly importing weeds that could reshape its unique wilderness forever.

Steven Chown of Stellenbosch University in Matieland, South Africa, and colleagues vacuumed the clothes and bags of some 33,000 tourists and 7100 scientists who visited Antarctica between 2007 and 2008. They found an average of 10 plant seeds on each person (Proceedings of the National Academy of Sciences, DOI: 10.1073/pnas.1119787109).

Because many of them had visited other cold places as well, they were carrying species likely to survive in Antarctica. Scientists, especially field scientists, were five times as seedy as the tourists.

Most seeds were grasses or dandelions that make good invaders, especially now parts of Antarctica are warming up. Poa annua, an annual bluegrass, is already making itself at home around four research stations.

Antarctica has unique biodiversity, Chown says. “Colonising species could transform these landscapes to the detriment of indigenous species,” he says, and destroy their uniqueness. Colonisation happens naturally, but humans accelerate it and bring in species that wouldn’t get there on their own.

“People would notice if we added a few random spots of bright pink paint to a Rubens,” says Chown. But many of us do the same to natural systems “without a hint of regret”.

Seeds of weeds trash Antarctica

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Get some backboneAn eel-like creature from 505 million years ago was a forerunner to all vertebrates, from fish to humans. Fossil evidence confirms that Pikaia gracelens had a rod of elastic tissue running along its back, making it the oldest chordate ever found (Biological Reviews, DOI: 10.1111/ j.1469-185X.2012.00220.x).

Dione has oxygenThe list of oxygenated worlds is growing. Measurements from NASA’s Cassini spacecraft suggest Saturn’s moon Dione has a thin layer of oxygen floating above its surface. It is the second of Saturn’s moons found with oxygen in its atmosphere. Mostly ice, Dione lacks liquid water that would make it friendly for life.

Non-stick spidersHow come spiders don’t get stuck to their own webs in the same way that their insect prey do? They use three tricks: their legs are covered with hair to minimise contact with the sticky web, and coated in a chemical to reduce stickiness. Plus, they are masters at tip-toeing (Naturwissenschaften, DOI: 10.1007/s00114-012-0901-9).

Gruesome packagingA US law that would force tobacco companies to adorn cigarette packaging and advertisements with large gruesome images depicting the health effects of smoking will get a second chance. On 5 March, the US government appealed against a ruling that said the regulations violated tobacco companies’ right to free speech.

Preparing for lift-offSpaceX’s Dragon spaceship is one step closer to blasting off for the International Space Station. On 1 March, engineers fuelled a Falcon 9 rocket in preparation for the uncrewed Dragon’s launch – scheduled for April. It will be the first private shot to the orbital outpost.

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