Have humans living within the Greater Cape Floristic Region used the same plant species through time?

Abstract

An improved understanding of indigenous plant use by humans over time may assist in our understanding of how the Greater Cape Floristic Region's flora (GCFR) contributed to the survival of modern humans. To address this issue, two databases were created documenting all archaeological (all plant species found in archaeological sites dating 0–80,000 BP) and contemporary (all plant species in the modern-day ethnographic literature of the last 400 years) that occur within the GCFR. Sixty-three plant species were shared between the archaeological (205 plant species) and contemporary (672 plant species) databases. This overlap is significantly (p < .001) more than expected (~15 species) if the samples were drawn at random from the available pool of species in the GCFR (11,423). Nonetheless, the overlap is a relatively low proportion of both databases (<1/3) and potential reasons for this mismatch are explored. Both databases were found to be incomplete: species accumulation curve projections suggest the total species list should be double the current number of plant species recorded for each database. Another potential reason for the mismatch is preservation bias in the archaeological record: most plant remains only preserve to 6000 BP, unlike charcoal samples (31% of all samples) that preserve up to ~80,000 BP. Also, there has likely been a modern-day shift to utilising plant species that are easy to process. This is the first study to investigate similarity in human use of specific plant species over time in any region. The significant overlap in plant species used at least as far back as 80,000 BP supports explorations of the GCFR's current flora from the perspective of earlier foragers.