Pathogens provide an ever-changing target for our control efforts, constantly evolving in response to the treatments we use, and with new pathogens 'spilling-over' from other host species. This problem has been brought into even sharper focus by the emerging antimicrobial resistance crisis, where pathogen evolution threatens to undo decades of advances in medicine. We study this problem using a mixture of mathematical modelling and experiments to understand and predict pathogen evolution. In the first part of this talk I will present work showing that we can predict bacterial species ability to both jump the host barrier and to shape microbiome composition from their sweet of cooperative traits, and that the evolution of these cooperative traits may in many cases be a by-product of bacterial warfare. In the second part of this talk I will examine the strategies we use to combat the antimicrobial resistance crisis, showing that our current focus on resistance to last resort antimicrobials is misguided, and that evolutionary theory suggests we must perform an about-face and focus on resistance to frontline antimicrobials.