Life as we see it in our planet today has been shaped by many different biological processes, particularly natural selection, during billions of years. These processes leave a signature in our genomes in the form of differences between species, or between individuals of the same species. Interrogating these patterns of genome diversity we can infer what are the forces that affect living organisms, how and when they act and how do they affect such various things as biodiversity, human emotions or the differential susceptibility of different persons to certain diseases. All this knowledge empowers us to control our future but, above all, it is very fun to obtain.