Proceedings of the National Academy of Sciences

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Unexpected rise in carbon-fuelled ocean acidity threatens shellfish, say scientists

The world's oceans are becoming acidic more quickly than climate change models predict, according to scientists who claim it will have a dramatic impact on marine ecosystems.Water samples collected around an island in the eastern Pacific over the past eight years showed seawater had acidified more than 20 times faster than scientists expected. The effect could be devastating for shellfish and other crustaceans, because acidic waters dissolve calcium carbonate used by the organisms to make their protective shells.Oceans absorb about a third of the carbon dioxide released into the atmosphere by human activities. When the gas dissolves in water, it forms carbonic acid, which alters the ocean's delicate chemical balance. The increasing acidification of the oceans is likely to have impacts that run throughout the marine ecosystem, because the organisms most affected are at the bottom of the foodchain.Timothy Wootton, a biologist at the University of Chicago, led a team of researchers who analysed the acidity, salinity and temperature of water around Tatoosh Island off the northwestern coast of Washington state. Over eight years, the pH level of the water fell by 0.36 to about 8.1, more than 23 times more than the predicted fall of just 0.015 points. Water is neutral if its pH is seven, and becomes more acidic as the pH falls below that.Writing in the US journal Proceedings of the National Academy of Sciences, the scientists raise concerns at how rapidly the process is happening and the impact it could have. "Acidification may be a more urgent issue than previously predicted, at least in some areas of the ocean," the authors write.According to computer models of the local marine life, the rise in acidity is likely to cause substantial falls in the numbers of mussels and large goose barnacles, while algae and populations of smaller barnacles may increase. In turn, the changing distribution of these organisms will have effects on marine life that feed on them.Last month, researchers warned that a new global deal on climate change would come too late to save many of the world's corals. A report from the Carnegie Institution at Stanford University in California found that carbon dioxide emissions are likely to acidify seawater enough to cause widespread damage to major reefs, including the Great Barrier Reef in Australia. Even stringent cuts designed to stabilise greenhouse gas levels still put more than 90% of the world's reefs in jeopardy."Declines in seawater pH were expected to happen very slowly, so we've been lax in dealing with the problem, but our study shows ocean acidification may be happening much quicker," said Wootton.FoodWaterEndangered speciesWildlifeClimate changeguardian.co.uk © Guardian News & Media Limited 2008 | Use of this content is subject to our Terms & Conditions | More Feeds

World's oldest nuclear family unearthed in Germany

DNA extracted from bones and teeth in a 4,600-year-old stone age burial has provided the earliest evidence for the nuclear family as a social structure. The find consists of two parents and two sons who were buried together after being killed in a violent conflict over some of the most fertile farming land in Europe.The archaeologists who examined the bones said the burial provides evidence of a shift in social organisation from communal living to societies with large social differences between people. "It provides evidence that will allow us to understand the rise of societies that are more modern," said Dr Alistair Pike, an archaeologist at Bristol University who was a member of the team.The site was discovered four years ago during quarrying at Eulau in Saxony-Anhalt, about 120 miles south-west of Berlin. Along with some individual burials there are four group burials in which more than one individual was interred at the same time. The group burials, which appear to have happened together, tell a story of violent deaths. One skeleton has an arrow tip lodged in one of its vertebrae. Several of the skeletons have fractures that have not healed, showing that they must have happened shortly before death. Pike said they were probably trying to hold on to land in the face of raids. "This particular area is considered to be one of the most fertile areas of Europe. So if people are looking for areas to settle they will be looking for these kind of soils, which might have contributed to some of the interpersonal violence," he added.The people were members of the Corded Ware culture, named after their practice of decorating pots using twisted cord. By analysing bone samples, the scientists have shown that the arrangement of the bodies reflected family groups. Children who were related to the adults in the same grave were buried facing them; unrelated children were buried behind the adults. "Whoever buried them knew ... it was very important that you signify genetic relationships in the way that you lay the [bodies] out," said Pike. The finds are documented in the Proceedings of the National Academy of Sciences.Burial as a nuclear family is different from the custom earlier in the neolithic era. Typically, archaeologists find mass graves of hundreds of individuals with little to distinguish them. The team also examined evidence of where the people had grown up by analysing the combination of different forms of strontium in their teeth. The ratio of strontium isotopes depends on a person's diet during childhood and reflects the dominant rock types in the area. While the men and children had a strontium profile that indicates they were raised nearby, the women came from outside the area. Pike said this was evidence of a patrilocal society, where families "married out" their daughters, either to avoid inbreeding or build allegiances with neighbours.ArchaeologyGeneticsGermanyguardian.co.uk © Guardian News & Media Limited 2008 | Use of this content is subject to our Terms & Conditions | More Feeds

All in the family - scientists discover gene for cocaine addiction

It has become commonplace for people who are overweight to attribute their waistline to their DNA. Now, celebrities caught snorting cocaine might also be able to blame their parents.Scientists reported yesterday the discovery of a gene that increases the chances of becoming hooked on the drug. Addicts were 25% more likely to carry the gene variant than people who did not use cocaine, a study found.The discovery is unlikely to lead to a treatment for cocaine addicts, but scientists hope it could be used to screen for those most likely to have problems kicking the habit if they ever try the drug."If you are a carrier of this gene variant, the likelihood of getting addicted to cocaine is higher," said Rainer Spanagel, a professor of psychopharmacology at the Central Institute of Mental Health in Mannheim, Germany, who led the study. "You can certainly use this as a vulnerability marker for cocaine addiction."He said people found to be susceptible to cocaine addiction could be given counselling or protected with experimental vaccines now being developed. The vaccines are designed to block the "high", or euphoria, associated with the drug.Last week, an analysis by the European Union's drug agency put Britain at the top of its list of cocaine-abusing states, with its users outnumbering all those elsewhere on the continent.Genetic factors, scientists believe, account for 70% of cocaine addiction, making it as heritable as schizophrenia and other mental health conditions. Studies of twins suggest alcoholism is about 50% genetic.Researchers linked a version of the CAMK4 gene with cocaine addiction after studying mice that had been genetically modified to alter the gene. One particular breed was affected more strongly by the drug and became addicted quicker than others in the group, according to the study in the US journal, Proceedings of the National Academy of Sciences.To see if the gene played a role in cocaine addiction in humans, the researchers ran genetic tests on 670 cocaine addicts and more than 700 matched non-users. While 40% of non-users carried the gene, it was found in half of the addicts.DrugsDrugs and alcoholMedical researchGeneticsHealthguardian.co.uk © Guardian News & Media Limited 2008 | Use of this content is subject to our Terms & Conditions | More Feeds