A common line of thought in contemporary metaethics is that certain facts about the evolutionary history of humans make moral realism implausible. Two of the most developed evolutionary cases against realism are found in the works of Richard Joyce and Sharon Street. In what follows, I argue that a form of moral realism that I call proper-function moral realism can meet Joyce and Street's challenges. I begin by sketching the basics of proper-function moral realism. I then present what I take (...) to be the essence of Street's and Joyce's objections, and I show how proper-function realism answers them. (shrink)