One of the most intriguing paradoxes in biology is that oxygen - upon which we depend so critically for life - is highly reactive, jeopardizing the health of our cells. When we breathe, we unwittingly leak reactive oxygen molecules as by-products, and these have been implicated in many ailments, from ageing to infertility. One emerging pattern is that the sexes differ in their vulnerability to oxidation, but the evolutionary implications of this have been hitherto unrealized. We build on the exciting new theory that oxidation mediates the evolution of many of the differences and conflicts we see between males and females. Our project will stand at the forefront of scientific discovery, exploring this theory through robust experimentation.