There are a great many theories as to why the well-known gap between male and female longevity exists. Here, researchers look at differences in lifestyle choices and pin the blame on smoking and drinking: "Since the late 1990s there has been evidence that women now outlive men in all countries of the world. Historical records show that in Sweden, Denmark, Italy, The Netherlands, England and Wales, the life expectancy of women has exceeded that of men since the mid to late 18th century, and there has been speculation about the causes of gender differences since that time. Different explanations have been postulated for this gender gap, including biological factors. However, there is considerable variability, and sometimes rapid change, in the magnitude of the female mortality advantage over time and in different countries, a variability that poses challenges for simple biological explanations for the gender gap. Earlier research suggested that health behaviours, and particularly men's higher prevalence of smoking, were a major cause of gender differences in the US. Here, we use contemporary mortality data for 30 European countries to examine the extent to which men's higher mortality can be explained by smoking-related and alcohol-related deaths. ... Smoking-related deaths accounted for around 40% to 60% of the gender gap, while alcohol-related mortality typically accounted for around 20% of the gender gap. The range in the contribution of smoking-related deaths reflects gender differences in the uptake of smoking by gender in earlier decades."