Archaeologists study the material remains of cultures and societies of the past. These remains include evidence of the plants people collected, grew, and utilized for food, medicine, raw material, and ceremony. Direct evidence exists primarily in the form of charred seeds, wood, and other plant parts such as nut shells, rind, corn cobs, corn cupules, phytoliths and pollen. On a rare occasion, coprolites (paleofeces) survive, containing the seed residue of prehistoric meals. Scientists who study ancient plants are called paleobotanists or archaeobotanists.
Indirect evidence of plant use comes from cooking pots and storage pits, hearths, charred food residue found on containers, artifacts like hoes, scrapers, and scoops used to grow or process plants, drawings, and even the footprints of ancient gardens. And as the saying goes “we are what we eat.” Human bone chemistry sometimes offers clues to crop foods in the diet.
Until archaeologists devised ways to recover very small, sometimes microscopic-size, seeds from soil and flotation samples collected at excavated sites, most evidence ended up tossed away with the back dirt. Small seeds, such as tobacco, goosefoot, little barley, and maygrass, were not captured in standard-sized mesh sifting screens and, hence, went undetected. Modern microscopes, especially scanning electron microscopes, greatly aid in identifying varieties of seed remains. Nevertheless, not all sites produce such evidence. The lifestyles of ancient peoples, the soils at a site, conditions for preservation, and the interests and techniques of the archaeologist all affect whether ancient plant remains exist, are preserved, and will be recovered.
Even after plant remains have been found, they must be identified and classified by the paleobotanist. And determining whether a seed represents a wild, cultivated, or domesticated plant is not always easy.