Small is big: The microfossil perspective on human–plant interaction

Abstract

The archaeological record contains only scattered and incomplete clues to the scope and complexity of past human behavior, and archaeologists must develop every possible source of useful information. Although much overused of late, the truism that absence of evidence is not evidence of absence holds particular force in archaeology and nowhere more than in the prehistory of human–plant interaction. Until recently, the reconstruction of plant use and domestication has been biased by a necessary dependence on macrobotanical remains preserved in arid environments or through serendipitous carbonization. Microbotanical analyses have proven increasingly valuable in balancing the record. Over the last few decades, phytolith (plant opal silica bodies) and starch grain studies have contributed significantly to the multiproxy reconstruction of past environments, human use of plants, and the pathways of plant domestication (e.g., refs. 1 and 2). This observation is especially true in humid regions, where conditions do not favor the preservation of macrobotanical remains, and in areas where tubers were important sources of plant foods; tubers are soft structures that often are consumed in their entirety, and they tend to leave few macro remains even under optimal preservation conditions. Working in the humid tropics of Central America, Dickau et al. (3) demonstrate in this issue of PNAS the power of archaeological starch grain analysis by using this proxy to elucidate the differential movement and adoption of both seed and root crops in western and central Panama beginning ≈7,800 years ago.