Spices and herbs are stimulants. Not necessarily pharmacological, but sensory: they stimulate our senses of taste and smell in foods that are otherwise bland. The human diet must have gotten a little boring when our ancestors first learned to cultivate grains and root crops and began to lean heavily on these starchy staffs of life, after millions of years of eating this and that as hunter-gatherers. So when did humans start spicing up their monotonous new diet? Very early--in the Americas, even before the widespread use of cooking pots, according to a new report on the archaeology of the chilli "pepper." A group of fifteen scientists led by Linda Perry of the Smithsonian Museum of Natural History published their results in this week's Science.
Say Perry and colleagues: "The presence of domesticated plants used as condiments rather than as staple foods during the Preceramic period indicates that sophisticated agriculture and complex cuisines arose early throughout the Americas and that the exploitation of maize, root crops, and chili peppers spread before the introduction of pottery."
Perry, L. et al. Starch fossils and the domestication and dispersal of chili peppers (Capsicum spp. L.) in the Americas. Science 2007, 315, 986-88. http://dx.doi.org/10.1126/science.1136914