According to a survey report of the University of British Columbia in Canada, left-handed people are more prone to accidents than ordinary people, and their average life expectancy is 9 years shorter than that of right-handed people. A survey of thousands of deaths in southern California shows that the average life expectancy of left-handed people is 66.3 years, while that of right-handed people is 75 years. Professor Stanley from the University of British Columbia. The survey conducted by Collen also shows that the average life expectancy of left-handed men and women is also different. The average life expectancy of left-handed men is 63 years and that of women is 72 years. The average life expectancy of right-handed men is 72 years and that of women is 77 years. Collen stressed that many factors lead to the above results, such as the poor health of left-handed people and the difficulty for left-handed people to operate machines designed for most right-handed people. According to the survey, the death rate of left-handed people caused by accidents is five times higher than that of ordinary people. Left-handed people suffer from diabetes and immune system diseases more than right-handed people. In addition, the proportion of left-handed babies born in dystocia is twice that of normal babies, so left-handed babies may have other pathological reasons. Prior to this, a survey of 1900 students at the University of British Columbia showed that left-handed people were 89% more likely to be injured by accidents than right-handed people. At present, it is estimated that there are more than 400 million left-handed people in the world.