the-BA : Science News Digest - 16 February 2007

Chilli peppers (Image copyright: istockphoto.com)

Revealed in the news this week: the promise of a bionic eye, new neurons for the human brain and an Antarctic water world. Plus, the ancient condiment of choice...

A bionic eye able to give blind people back their sight could be on the market within two years, offering hope to millions of people suffering vision loss due to degenerative eye diseases, according to a scientist speaking at the annual meeting of the American Association for the Advancement of Science. Six patients who received an electronic retinal implant are now able to detect light, distinguish between objects and determine direction of motion, reported the Daily Telegraph.

Lead researcher Professor Mark Humayun, from the University of Southern California, said: ‘We expected that all they would be able to do would be to differentiate between light and dark, but were amazed to find they can tell the difference between objects such as a plate, a knife and a cup, and tell which way people are moving across their field of vision.’

The device enables patients to see spots of light occurring in different patterns. It uses a tiny camera in the lens or on a pair of glasses to capture images – information that is then transmitted to a radio receiver implanted behind the patient’s ear. A grid of electrodes implanted in the retina receives electrical signals from this and stimulate retinal nerve cells to produce the electrical impulses to the brain. A more advanced version that could provide greater resolution images will now be tested on 75 subjects.

New research has shown that the adult human brain contains stem cells that are able to create new neurons in the part of the brain that deals with smell, reported BBC News. This capacity was known in mice and rats but, until now, it wasn’t known whether a similar system existed in human brains.

‘This opens another direction by which we may discover ways to repair human brains that are damaged from injury or diseases, and underscores the importance of animal research in guiding biomedical research in humans,’ said Dr Mark Baxter of Oxford University.

A set of five genes linked to the onset of type 2 diabetes has been identified by an international team of scientists. The disease is caused by both genetic and lifestyle factors, with up to 70 per cent of the genetic risk thought to be accounted for by the five reported genetic variants. The discovery paves the way for a test that could help identify people predisposed to developing the condition, as well as providing targets for developing better treatments.

‘The two major reasons why people develop type 2 diabetes are obesity and a family link,’ said Professor Philippe Froguel, one of the research leaders, in the Times. ‘Our new findings mean that we can create a good genetic test to predict people’s risk of developing this type of diabetes. If we can tell someone that their genetics mean they are predisposed towards type 2 diabetes, they will be much more motivated to change things such as their diet to reduce their chances of developing the disorder.’

Also this week, politicians from around the world reached a new agreement on climate change at a forum organised by Globe (Global Legislators Organisation for a Balanced Environment). Importantly, reported the Daily Telegraph, China and the US were among the 20 countries that signed the resolution paving the way for a replacement to the Kyoto Protocol, which expires in 2012. World leaders agreed that both rich and poor countries should aim towards new targets for capping carbon dioxide emissions and that they would work towards having a replacement in place by 2009. Although the resolution is non-binding, it was seen to signal a shift towards greater action. Developing nations such as Brazil and Mexico were among those present.

US senator Joe Lieberman predicted that a law on cutting emissions would be enacted by the US Congress by the end of next year.

According to the Guardian, scientists have discovered that there is a vast water world under the Antarctic ice sheet that will necessitate a revision of how global sea levels are predicted to rise in response to climate change. 145 underwater lakes were previously known to exist but now satellite data mapping the rise and fall of the overlying ice has revealed new bodies of water ranging up to 193 square miles in size, many of which are connected by fast flowing rivers.

The researchers, who published their results in Science, say the surprise is the rate at which changes are occurring – rather than taking years or even decades, they observed that large changes can happen in a matter of months. The faster that melting ice from the heart of the continent can reach the open sea, the faster water levels will rise. The latest report by the Intergovernmental Panel on Climate Change said that the biggest unknown in predicting sea levels was an uncertainty about the response of ice sheets to climate change.

Meanwhile, further support for the past existence of water on Mars has been provided by NASA’s Mars Reconnaissance Orbiter. Colour images of the deep valley Candor Chasma from a high resolution camera reveal discoloured rocky ridges – evidence that prolonged contact with a fluid caused chemical reactions in the rock.

’It is hard to say how long ago the fluids were there - hundreds of millions or perhaps a billion years ago,’ said Geologist Dr Chris Okubo in the Guardian. ‘But the fact that we see evidence for chemical reactions between the fluids and the rock means that the fluids were sitting there for quite a long time ... that's perhaps good if you want to look for any habitable areas that might support any biological activity.’ Dr Okubo studies similar geological evidence for ancient flowing water on Earth.

Chimpanzees enjoyed their own Stone Age, according to a discovery of stone tools in the Tai rainforest in West Africa. Scientists found evidence that chimpanzees were using simple hammers to crack open nuts more than 4,300 years ago. This is the first indication of an ancient culture among chimps.

’It's not clear whether we hominins [ancient and modern humans] invented this kind of stone technology, or whether both humans and the great apes inherited it from a common forebear,’ Dr Julio Mercader of the University of Calgary, Canada, said in the Independent. ‘There weren't any farmers living in this region 4,300 years ago, so it is unlikely that chimpanzees picked it up by imitating villagers, as some scientists used to claim.’

Researchers have discovered that helicobacter pylori – the bacterium responsible for the majority of painful stomach ulcers and present in half of the world’s population – has been in the human digestive system since modern man migrated from Africa more than 60,000 years ago. The Telegraph reported that research is being undertaken to use the bacterium to help fine-tune studies of ancient human migration patterns – currently based on analysis of human genetic similarities and differences – since it contains 50 times more genetic variation than the humans who carry it.

In other news in the Times, a study of almost 9,000 families has highlighted to women the importance of eating fish when pregnant, for the benefit of their child’s brain development.

And finally...

Prefer your food a little hot? Well, new archaeological evidence reported in the Independent has revealed that our ancestors were the same – chilli peppers have been helping us to spice up bland dishes for thousands of years.

Researchers were able to use fossilised grains of starch to identify the remains of chillis among other food remnants, thanks to their distinctive microscopic shape. The oldest chilli starch grains were found at two sites in Ecuador, dated to 6,100 years ago, but the use of the spice soon spread through south and central America before going global. So, next time you make a con carne, remember you’re using the world’s oldest known condiment.