It sounds like a story missing from Rudyard Kipling’s Just So stable, but how the turtle got its sophisticated and elegant shell is a question that has perplexed scientists for years. Now, thanks to the discovery in China of a 220m-year-old turtle fossil – the oldest known – the mystery seems to have been solved: the shell is a bony extension of the backbone and ribs, the bones having flattened and fused during evolution. This seems to rule out an earlier hypothesis which held that bony plates in the skin, rather like those found in modern crocodiles, came together to form the turtle’s hard, protective covering.
The problem for scientists probing the mystery had been a lack of fossils demonstrating stages in the evolution of the shell. The new fossil, however, has only a partial shell, signifying an evolutionary staging post. “This is the first turtle with an incomplete shell,” said Olivier Rieppel, chairman of the The Field Museum’s department of geology, who, with colleagues in China and Canada, carried out the analysis. Their work is reported in Nature magazine this week.
Galaxy harbours sweetness of life
More evidence that deep space harbours the building blocks of life comes from scientists who have discovered a simple sugar molecule in a region of our galaxy where habitable planets theoretically could exist. The international team, including representatives from University College London, found the sugar glycolaldehye in a region of space some 26,000 light years from the earth where stars are continuously being formed. The researchers used the France-based IRAM radio telescope to detect the “signature” of the sugar molecule in the clouds of dust and gas floating in space. Their conclusions are published this week on the Astro-ph website.
Glycolaldehye is a simple sugar but it can react with another substance, propenal, to form ribose, a key constituent of RNA. RNA and DNA comprise the hereditary mechanism of all living things. RNA is thought to be the central molecule in the origin of life, the molecule which made possible reproduction in the earliest living organisms. So the discovery of organic sugar in a part of space which could support life is an important step in the hypothesis that other forms of life might exist in the universe.
Cause found for pain after healing
Researchers have uncovered a physical cause for the chronic pain that afflicts some people after damage to, say, a hand or foot. It is a consequence of brain changes which “rewire” the areas dealing with emotion, pain and the temperature of their skin, they say.
For most individuals, the pain of the injury stops after the limb heals. But for some 5 per cent of patients, the pain continues long after healing. Called Complex Region Pain Syndrome, it can last the rest of the individual’s life, causing intense suffering. Scientists at Chicago’s Northwestern University discovered that, following trauma, the white matter of the brain – the cables that carry messages between brain cells – becomes rearranged.
“This is the first evidence of brain abnormality in these patients,” said Prof Vania Apkarian of Northwestern. “People didn’t believe these patients. This is the first proof that there is a a biological underpinning for the condition.” The finding is expected to stimulate research into drugs to treat the condition. The research appears in this week’s Neuron journal.
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