– There's a reason we don't typically call Earth's oldest person the oldest woman in the world—the oldest person is pretty much always a woman. In fact, just two of the world's 53 living supercentenarians (people 110 and older) are men, reports IFL Science. But why is the longevity gap so stark, and how long has it been so? An international team of researchers is investigating the lifespans of men and women born between 1800 and 1935 in 13 developed nations in search of answers, reports PhysOrg, and they've found that women's superior longevity only emerged recently. Before 1840, death rates were very similar between men and women. But since those rates began to plummet in 1880 thanks in large part to improved diets, vaccinations, and better health care, female death rates have dropped 70% faster than male ones, and heart disease seems to be holding men back the most, the researchers report in Proceedings of the National Academy of Sciences. Men may be more biologically susceptible to cardiovascular health problems, and their different weight distribution could play a role here, reports Live Science. The researchers plan to further explore the differences between male and female biology, genetics, and lifestyles to look for answers. (The oldest man in the US says his trick has been to enjoy a can of beer a day.)