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CANBERRA, Sept. 23 (Xinhua) -- A genetic study on Friday found Aboriginal Australians are descended from the first people to leave Africa up to 75,000 years ago.Researchers from the University of Western Australia, Murdoch University and an international team analyzed genetic material of a 100-year-old West Australian Aboriginal man's hair, and found he was directly descended from a migration out of Africa into Asia.The study revealed that Australian Aboriginal ancestors split from the first modern human populations to leave Africa, between 64,000 and 75,000 years ago, at least 24,000 years before other human migrations.According to Dr. Joe Dortch, an archaeologist at the University of Western Australia, the discovery rewrites the history of the human species by confirming humans moved out of Africa in waves of migrations rather than in one single out-of-Africa diaspora.It also rewrites the story about how Aborigines arrived in Australia some 50,000 years ago."So far there are no [archaeological] sites that are over 50, 000 years old so it puts a time limit on that and focuses our future efforts," he said in a statement released on Friday.Dr. Dortch believes the finding will foster a sense of pride in modern Australian Aborigines."No-one else in the world can say 'I am descended from people who have been here 75,000 years'."Associate Professor Darren Curnoe, leader of the Human Evolutionary Biology Lab in the School of Biological, Earth & Environmental Sciences at the University of New South Wales, said the study powerfully confirms that Aboriginal Australians are one of the oldest living populations in the world, certainly the oldest outside of Africa."Australians are truly one of the world's great human populations and a very ancient one at that, with deep connections to the Australian continent and broader Asian region. About this now there can be no dispute," he told Xinhua in an email note.Meanwhile, Professor Alan Cooper, Director of the Australian Centre for Ancient DNA (ACAD) at the University of Adelaide, said while this is a major step forward, the key unresolved question remains the unique story of Aboriginal history within Australia, such as what has happened in those 50,000 years of life in the harsh Australian environment."Unfortunately, the information from a single individual tells us very little about this fascinating, and critically important part of human history. Aborigines are one of the oldest continuous human populations outside Africa, as they note in the paper, and due to the geographic isolation and limited archaeological records remain one of the most mysterious chapters in human history," he told Xinhua on Friday.The study is published on Friday in the journal Science.Indigenous Australians are the original inhabitants of the Australian continent and nearby islands. They together make up more than 2.5 percent of Australia's population.

WELLINGTON, Aug. 8 (Xinhua) -- A New Zealand study has found that people who work at least 50 hours a week can be up to three times more at risk of alcohol problems than people who work fewer hours.The study, conducted by the University of Otago, used data that followed more than 1,000 people born in Christchurch in 1977 through to age 30.Study leader Dr Sheree Gibb said it aimed to examine whether working hours were related to alcohol problems in early adulthood.Data from more than 1,000 participants at ages 25 and 30 showed a significant association between longer working hours and alcohol- related problems.Longer working hours were associated with higher levels of alcohol problems including frequent alcohol use and alcohol abuse or dependence.People who worked 50 hours or more on average a week were 1.8 to 3.3 times more likely to have alcohol-related problems than those who were not working, and about 1.2 to 1.5 times more likely to have alcohol-related problems than those who worked 30 to 49 hours a week.The higher risk of alcohol abuse for those who worked longer hours was evident in both men and women, according to the study.Gibb said the finding could suggest a need for consideration of policies and programs targeting individuals who worked long hours, with the aim of reducing rates of alcohol-related problems.The article had been accepted for publication by the UK-based journal Addiction.

BEIJING, July 26 (Xinhuanet) -- Some forms of medical research involving animals containing human material should be more tightly regulated, a report warned.The warning was issued on Friday by an expert working group from the Academy of Medical Sciences in Britain.The report suggested the ban of the use of animal cells that can produce human sperm or egg cells. "We don't want scientists to cause problems for the future by overstepping the mark of what is publicly acceptable," said Professor Robin Lovell-Badge, a member of the expert working group.The controversy partly originated from a medical research in Britain. Three years ago, the researchers produced human embryos with the nucleus hollowed cow eggs, according to the Associated Press."This is a complex research area and there should be an ongoing dialogue between scientists, regulators and the wider public to address emerging issues." said Martin Bobrow, a professor of medical genetics at the University of Cambridge.

BEIJING, Sept. 2 (Xinhuanet) -- Firefighters who worked in the wreckage of the World Trade Center in 2001 were 19 percent more likely to develop cancer than those who were not there, according to a study.The study, published Thursday in the British medical journal The Lancet, surveyed cancer occurrence in nearly 10,000 male firefighters in the seven years after Sept. 11, 2001. (There were too few women to create a meaningful sample size.)The 9/11 attacks occurred on Tuesday, Sept. 11, 2001. As a result, the World Trade Center collapsed, and nearly 3,000 Americans killed. Among the 2,753 victims killed in the World Trade Center were 343 firefighters.There were 263 cancer cases in the exposed population, showing a cancer rate 19 percent higher than that of the group not exposed.The study indicated that cancers like melanoma, non-Hodgkin’s lymphoma, thyroid and prostate cancer occurred more frequently among exposed firefighters than in the general population. But occurrences of lung cancer did not increase.The findings “provide information that there may be a significant cancer risk for these people”, said Dr. James Melius, the administrator of the New York State Laborers’ Health and Safety Trust Fund and one of the peer reviewers of the study.But the results were far from conclusive. “This is not an epidemic,” said Dr. David J. Prezant, a lead researcher and the chief medical officer for the New York Fire Department.

STOCKHOLM, July 7 (Xinhua) -- A patient has been given a new trachea made from a synthetic scaffold seeded with his own stem cells in a Stockholm's hospital, the Swedish medical university Karolinska Institutet said on Thursday.The operation was performed on June 9th at Karolinska University Hospital in Huddinge and the patient, a 36-year old man, has been well on the way to recovery and would be discharged from the hospital on Friday, the university said in a statement.The patient had been suffering from late stage tracheal cancer with the tumor had reached approximately 6cm in length and was extending to the main bronchus.Since no suitable donor windpipe was available, the transplantation of the synthetic tissue engineered trachea was performed as the last possible option for the patient.The successful transplantation of tissue engineered synthetic organs, referred to as regenerative medicine, could open promising therapeutic possibilities for the thousands of patients who suffer from similar conditions.Transplantations of tissue engineered windpipes with synthetic scaffolds in combination with the patient's own stem cells as a standard procedure means that patients would not have to wait for a suitable donor organ.This would be a substantial benefit for patients since they could benefit from earlier surgery and have a greater chance of cure, according to the statement.