Integrating ecological release into the domestication equation

The ancient domestication of plants and animals permitted the agricultural yields necessary to feed higher densities of humans, leading to urbanism and eventually imperialism, further permitting humanity to culturally develop into modernity. Consequently, understanding what drove the evolution of domestication traits in prehistory is one of the most compelling areas of inquiry in the archaeological sciences. Over the past few years, new theories about what domestication is and how it unfolded in prehistory have been proposed. Among these novel ideas, ecological release, defined as the removal of a population from predation pressure (including herbivory and parasitism), has been proposed as a key driver. The removal of isolated populations of plants and animals from external stressors through cultivation permitted them to evolve a predictable suite of traits (the domestication syndrome). Support for this view comes from studies of island biogeography, whereas organisms that have evolved to adapt to oceanic islands express a similar assemblage of evolved traits (the island syndrome). Both syndromes include, for plants, an increase in plant mass, a loss of traits associated with seed-dispersal mechanisms, a loss of secondary defensive compounds, self-compatibility, and an increase in seed size; for animals, the traits include docility (reduction in fear responses), increased reproductive rates (or investment in offspring), coat-color changes, size changes (the Island Rule), and diminutive features (paedomorphism), including reductions in muzzle length and secondary sexual displays.