 One possible cost of this approach is the loss of a unified account of FMS. That is, there are now two routes to FMS: having sophisticated cognitive capacities or belonging to the human species. Whether one is cognitively sophisticated is determined purely by psychology, while whether one belongs to the human species is determined purely by biology. Of course, it is true that the human species (as opposed to its membership criteria) is characterized both psychologically and biologically, and so in this sense the second route to FMS is related to the first.