1. Preceramic maize from Paredones and Huaca Prieta, Peru.

    PNAS 109(5):1755 (2012) PMID 22307642 PMCID PMC3277113

    Maize (Zea mays ssp. mays) is among the world's most important and ancient domesticated crops. Although the chronology of its domestication and initial dispersals out of Mexico into Central and South America has become more clear due to molecular and multiproxy archaeobotanical research, importa...
  2. Pre-Columbian agricultural landscapes, ecosystem engineers, and self-organized patchiness in Amazonia.

    PNAS 107(17):7823 (2010) PMID 20385814 PMCID PMC2867901

    The scale and nature of pre-Columbian human impacts in Amazonia are currently hotly debated. Whereas pre-Columbian people dramatically changed the distribution and abundance of species and habitats in some parts of Amazonia, their impact in other parts is less clear. Pioneer research asked wheth...
  3. The cultural and chronological context of early Holocene maize and squash domestication in the Central Balsas River Valley, Mexico.

    PNAS 106(13):5014 (2009) PMID 19307573 PMCID PMC2664064

    Molecular evidence indicates that the wild ancestor of maize is presently native to the seasonally dry tropical forest of the Central Balsas watershed in southwestern Mexico. We report here on archaeological investigations in a region of the Central Balsas located near the Iguala Valley in Guerr...
  4. Starch grain and phytolith evidence for early ninth millennium B.P. maize from the Central Balsas River Valley, Mexico.

    PNAS 106(13):5019 (2009) PMID 19307570 PMCID PMC2664021

    Questions that still surround the origin and early dispersals of maize (Zea mays L.) result in large part from the absence of information on its early history from the Balsas River Valley of tropical southwestern Mexico, where its wild ancestor is native. We report starch grain and phytolith dat...
  5. Identification of teosinte, maize, and Tripsacum in Mesoamerica by using pollen, starch grains, and phytoliths.

    PNAS 104(45):17608 (2007) PMID 17978176 PMCID PMC2077075

    We examined pollen grains and starch granules from a large number of modern populations of teosinte (wild Zea spp.), maize (Zea mays L.), and closely related grasses in the genus Tripsacum to assess their strengths and weaknesses in studying the origins and early dispersals of maize in its Mesoa...
  6. Starch fossils and the domestication and dispersal of chili peppers (Capsicum spp. L.) in the Americas.

    Science 315(5814):986 (2007) PMID 17303753

    Chili peppers (Capsicum spp.) are widely cultivated food plants that arose in the Americas and are now incorporated into cuisines worldwide. Here, we report a genus-specific starch morphotype that provides a means to identify chili peppers from archaeological contexts and trace both their domest...
  7. Evidence for cultivar adoption and emerging complexity during the mid-Holocene in the La Plata basin.

    Nature 432(7017):614 (2004) PMID 15577908

    Multidisciplinary investigations at the Los Ajos archaeological mound complex in the wetlands of southeastern Uruguay challenge the traditional view that the La Plata basin was inhabited by simple groups of hunters and gatherers for much of the pre-Hispanic era. Here we report new archaeological...
  8. Processing of wild cereal grains in the Upper Palaeolithic revealed by starch grain analysis.

    Nature 430(7000):670 (2004) PMID 15295598

    Barley (Hordeum vulgare L.) and wheat (Triticum monococcum L. and Triticum turgidum L.) were among the principal 'founder crops' of southwest Asian agriculture. Two issues that were central to the cultural transition from foraging to food production are poorly understood. They are the dates at w...
  9. Teosinte before domestication: Experimental study of growth and phenotypic variability in Late Pleistocene and early Holocene environments

    Quaternary International 363 (2004)

    Agriculture arose during a period of profound global climatic and ecological change following the end of the Pleistocene. Yet, the role of phenotypic plasticity – an organism's ability to change its phenotype in response to the environment – and environmental influences in the dramatic...
  10. Evidence for the control of phytolith formation in Cucurbita fruits by the hard rind (Hr) genetic locus: Archaeological and ecological implications.

    PNAS 99(16):10923 (2002) PMID 12149443 PMCID PMC125074

    Many angiosperms, both monocotyledons and dicotyledons, heavily impregnate their vegetative and reproductive organs with solid particles of silicon dioxide (SiO(2)) known as opaline phytoliths. The underlying mechanisms accounting for the formation of phytoliths in plants are poorly understood, ...
  11. Effects of chronic oil-sediment pollution on the reproduction of the Caribbean reef coralSiderastrea siderea

    Marine Pollution Bulletin 26(5):276 (1993)

    In 1986 a major oil spill in Panama polluted and killed extensive areas of coral reefs. Five years afterwards, reef areas are chronically threatened by oil and large amounts of sediments containing toxic hydrocarbons trapped in mangroves. Sublethal effects of oil on coral reproduction were ...