Nutritional PharmEcology: Doses, nutrients, toxins, and medicines.

The synthesis of pharmacological techniques and concepts into ecology holds considerable promise for gaining new insights into old questions, uncovering new priorities for research and, ultimately, for consolidating a new sub-discipline within the ecological sciences-PharmEcology. We argue that this potential will best be realized if the boundaries of PharmEcology are drawn broadly to encompass not only toxins and medicines, but also nutrients. The hub of our argument is that PharmEcology shares with the established discipline of nutritional ecology an organismal focus, at the core of which is the notion of evolutionary function. From this functional viewpoint the dividing lines between chemicals traditionally considered as "toxins," "medicines," and "nutrients" are often thin, vague, heavily contingent and non-stationary, and thus provide a poor footing for an emerging sub-discipline. We build our argument around three points: nutrients and toxins are not so different, medicines and nutrients are not so different, and even in cases in which nutrients, medicines and toxins can be categorically distinguished, the biological actions of these compounds are heavily interdependent.