Everywhere in the world women live longer than men - but this was not always the case. The available data from rich countries shows that women didn't live longer than men in the 19th century. What makes women live more than men do today, and why is this difference growing in the past? We have only a small amount of evidence and the evidence isn't sufficient to reach a definitive conclusion. We know that biological, behavioral and environmental factors contribute to the fact that women have longer lives than men, however, we do not know how much the influence of each one of these factors is.