 Nicholas Agar (1993), for instance, supports the idea that the frog’s representation means there’s small, dark, moving frog food, a content intended to incorporate all of the properties causally responsible for the selection. By contrast, Manolo Martínez (2013) argues that it is not these properties themselves that enter into the content of the frog’s representation, but the natural kind (understood as a ‘homeostatic property cluster’) that accounts for the frequent co-instantiation of these properties. According to this proposal, the content of the frog’s representation would be something like there’s a fly. (This content ascription is also favored by Artiga 2019, who synthesizes Martínez’ approach with Millikan’s biosemantics, and extends it to representations that do not refer to natural kinds.)