All elements of the species, as depicted in Fig. The common ancestor of extant members of the C. pepo lineage was probably an annual, gourd-producing plant adapted to colonization of disturbed ground in riverine habitats. The archaeological record indicates that this free-living ancestral type initially became involved as a fundamental element of the New World agricultural revolution in the highlands of Oaxaca, Mexico more than 10,000 years ago. Subsequent evolution under both human and natural selection, coupled with human-mediated and 'natural' means of dispersal, has produced the remarkable suite of structural forms that now comprise the species and now show a global distribution. It appears, however, that this is not the full picture of domestication and differentiation of C. pepo .
Centers of origin are usually centers of genetic diversity.
The produce section of most U.S. supermarkets carries a more diverse sample of C. pepo than could be obtained from a full sample of modern field collections taken from throughout Mexico. While native C. pepo cultivar diversity in Mexico could have been extirpated during European colonization, it is also quite possible that one arm of the C. pepo lineage - diverse elements associated with ssp. Recent archaeological work has demonstrated that C. pepo was present in the eastern U.S. by 7,000 years ago. Data relating to this issue are a complex mix of biochemical genetics, archaeology, history, plant population biology, and personal inclinations. Assessment of the situation and interpretation of the data are difficult for the non-specialist as well as those actively engaged in the issue.