http://www.telegraph.co.uk/health/healthnews/9448608/Why-women-live-longer-than-men.html
I'm not sure I understood this, but it seemed interesting as mitochondria are discussed here so much.
Researchers have found that faults in a part of the "engine rooms" of cells known as the mitochondria have a greater effect on men than women.
That's because of a quirk of evolution their make-up or DNA is inherited solely from the mother and so is only screened by natural selection for mutations harmful to women.
Any that are damaging to men but not women slip through the net and slowly over time undermine the health of male cells.
I'm not sure I understood this, but it seemed interesting as mitochondria are discussed here so much.