Dolores R. Piperno

Smithsonian National Museum of Natural History, Washington, DC 20560

Smithsonian Tropical Research Institute, Balboa, Republic of Panama

Abstract

The development of agricultural societies, one of the most transformative events in human and ecological history, was made possible by plant and animal domestication. Plant domestication began 12,000–10,000 y ago in a number of major world areas, including the New World tropics, Southwest Asia, and China, during a period of profound global environmental perturbations as the Pleistocene epoch ended and transitioned into the Holocene. Domestication is at its heart an evolutionary process, and for many prehistorians evolutionary theory has been foundational in investigating agricultural origins. Similarly, geneticists working largely with modern crops and their living wild progenitors have documented some of the mechanisms that underwrote phenotypic transformations from wild to domesticated species. Ever-improving analytic methods for retrieval of empirical data from archaeological sites, together with advances in genetic, genomic, epigenetic, and experimental research on living crop plants and wild progenitors, suggest that three fields of study currently little applied to plant domestication processes may be necessary to understand these transformations across a range of species important in early prehistoric agriculture. These fields are phenotypic (developmental) plasticity, niche construction theory, and epigenetics with transgenerational epigenetic inheritance. All are central in a controversy about whether an Extended Evolutionary Synthesis is needed to reconceptualize how evolutionary change occurs. An exploration of their present and potential utility in domestication study shows that all three fields have considerable promise in elucidating important issues in plant domestication and in agricultural origin and dispersal research and should be increasingly applied to these issues.

See: http://www.pnas.org/content/114/25/6429.abstract.html?etoc

PNAS June 20 2017; vol.114; no.25: 6429–6437

Figure 1: The differences between teosinte and maize today in branching architecture and inflorescence sexuality. Teosinte has several long primary lateral branches terminated by tassels and secondary lateral branching, where female ears are located. Maize has a single main stem terminated with a solitary tassel. There are a few, very short primary lateral branches and no secondary branching. The cobs are located at the ends of the branches on the main stem in the positions occupied by tassels in teosinte. Reproduced from ref. 27.