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's the main reason women live longer than men? Why is this difference growing over time? There is only limited evidence and the evidence is not strong enough to make a definitive conclusion. We know there are biological, psychological and environmental variables which all play a part in the longevity of women over men, we don't know the extent to which each factor plays a role.

We know that women live longer than men, regardless of weight. But it is not due to the fact that certain biological or non-biological factors have changed. What are these new factors? Some are well known and relatively straightforward, like the fact that men smoke more often. Other are more complicated. For example, العاب زوجية (Glorynote writes) there is evidence that in rich countries the female advantage increased in part because infectious diseases used to affect women disproportionately a century ago, so advances in medicine that reduced the long-term health burden from infectious diseases, especially for survivors, ended up raising women's longevity disproportionately.

Everywhere in the world women tend to live longer than men
The first chart below shows life expectancy at birth for men and women. As we can see, every country is above the diagonal parity line - it means that in all nations baby girls can expect to live longer than a newborn boy.1

Interestingly, this chart shows that the advantage of women is present everywhere, global differences are significant. In Russia women live 10 years longer than men, while in Bhutan the difference is just half each year.

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In wealthy countries, the female advantage in longevity was smaller
Let's look at how the gender advantage in longevity has changed with time. The next chart shows male and female life expectancy when they were born in the US during the time period between 1790 and 2014. Two distinct features stand out.

There is an upward trend. Men and women in the US have a much longer life span longer today than a century ago. This is in line with historical increases in life expectancy everywhere in the world.

And second, there is a widening gap: The female advantage in terms of life expectancy used to be extremely small, but it grew substantially over the last century.

You can verify that these points are also applicable to other countries that have data by clicking on the "Change country" option in the chart. This includes the UK, France, and Sweden.