Meeting Abstract

S6.5  Monday, Jan. 5  The evolutionary mechanism of action of neurotoxins: punishment or reward? SULLIVAN, RJ; California State University, Sacramento; and University of California, Davis sullivar@csus.edu

Humans have not been exempt from plant-herbivore interactions. In an evolutionary timescale, human ancestors (hominids) were dependent primarily on wild plant foods, and thus were no less subject to herbivore offences than other animals. Ecological theory of hominid consumption and exploitation of wild plants anticipates avoidance of, or selective exposure to, plant secondary metabolites (PSMs) because of their harmful effects. The history of plant domestication is, in large part, a process of selective detoxification of wild plants for safe consumption by humans, but this process occurred very recently in evolutionary history. Many animals adaptively exploit PSMs, and research of self-medication by primates has contributed to theories of selective medicinal use of wild plants by hominids as a precursor to modern human drug behaviors. However, evolutionary ecological perspectives that see human interactions with common plant toxins as governed primarily by punishment from herbivore offences, are overshadowed by current neurobiological theories that emphasize reward and reinforcement as the principal dynamic affecting human substance use, including that of commonly-used PSMs like nicotine. My talk will engage with the evolutionary question of how important reward can have been when cast against the ubiquitous selection pressures from toxic PSMs in the wild plants that constituted the foods of our hominid ancestors, and will discuss contradictions between the punishment inherent in herbivore offence mechanisms and the reward emphasized in contemporary neurobiological theories of human drug seeking behavior.