"Evolution" is a scientific term. It means the way that animals and plants change over time, to become better adapted to their environments. For example, people sometimes like to talk about why humans first started to walk on two feet instead of using all 4 hands like apes do.
Evolution takes a long time to work, so it's common to talk about "millions of years of evolution", or "hundreds of thousands of years of evolution.
Society expects us to control our urges, but you can't fight against millions of years of evolution.