When humans walked out of Africa about 60,000 years ago and slowly made their way to Europe, their genes underwent an important mutation. The change allowed their body to survive the cold climate, but that came at a steep price that left many Europeans today prone to developing a serious mental illness, according to a joint study by Chinese and American scientists. The international research team led by Professor Li Ming of the Chinese Academy of Sciences’ Kunming Institute of Zoology found that a gene associated with schizophrenia appeared about 40,000 years ago, when the first modern humans arrived in Europe and wiped out the Neanderthals. The team’s research paper on the evolutionary pattern of schizophrenia risk variants was published in the July 4 issue of Oxford Journals’ Schizophrenia Bulletin . Schizophrenia is a mental disorder with a wide range of symptoms, most notably delusions and hallucinations, such as hearing voices, social withdrawal and aggressive behaviour. John Nash, the Nobel-prize winning mathematician who invented game theory and whose life inspired the film A Beautiful Mind , was one of the more than 20 million patients diagnosed with the disorder around the world annually. Mother Nature is fair. She gave you something, she took away something Li Ming, professor, Kunming Institute of Zoology A sufferer of schizophrenia can pass the disorder to their children, and a genetic variation called rs13107325 has been identified by scientists as associated with the occurrence of schizophrenia among the European population. One in 10 Europeans carried the gene, the study said, and by understanding its evolutionary history, researchers hoped to find a method to prevent or cure the disease. The studyfound the gene appeared when the first modern humans arrived in Europe. It was a cold period, as the eruption of a super volcano in Italy had caused temperatures around the globe to drop sharply. Like a “double-edged sword”, mutation brought both good and bad news, the researchers wrote in their paper. On one hand, the schizophrenia risk variant “significantly” reduced the threat of high blood pressure and hypertension, according to the research team. It also increased the body size of Europeans and their ability to obtain energy from protein, as well as accelerating the build-up of fat, which helped the early settlers to survive the long, dark winters with little available food. The bad news was, of course, a higher risk of schizophrenia for those who carried the mutation. “Mother Nature is fair,” Li said. “She gave you something, she took away something. While she allowed you to survive the harsh climate, she could also drive you crazy,” he said. Li stressed that the study did not suggest Europeans were more susceptible to schizophrenia than people of other races. Schizophrenia breakthrough: Scientists uncover key genetic contributor to disorder To the researchers’ surprise, although the variant existed only in European populations, people in Asia, Africa and other parts of the world suffered the same mental disorder at about the same rate, about 1 per cent. “Our study shows that though people of different races might have the same symptoms of schizophrenia, the driving mechanism behind the same disease could be very different,” Li said. “Because the rs13107325 gene only exists among Europeans, people in Asia, Africa and other parts of the world could get the disorder from a different genetic mutation caused by a different event, which remains to be discovered by further studies.” Although the gene could help the development of new drugs to treat schizophrenia, the drugs must be thoroughly checked for any potential side effects.