Spatial patterns, availability and cultural preferences for edible plants in southern Africa

We investigated whether cross-cultural food plant selection in southern
Africa is best explained by language ancestry, floristic environment or
subsistence strategy. Location: The flora of southern Africa region. Taxa:
All 1740 edible plant taxa of southern Africa, representing 711 genera in
156 families. Methods: Distribution data of plants were overlapped in
ArcMap with 19 language maps, eight biomes and all taxa with nutritional
data. Six correlations were estimated between five pair-wise distance
matrices (language ancestry, geographical proximity, floristic and edible
environments and utilised species) with Mantel tests using the ‘vegan’
package in R. Regression analyses were used to identify floristic and
cultural preferences in food plant selection. Results: Spatial
autocorrelation did not influence the selection of edible plants by the 19
language groups of southern Africa (r = -0.078). The floristic and edible
environments had a strong correlation (r = 0.9743) while the distance
matrices of the edible and actually utilised plants had a low correlation
for 13 of the language groups (r = 0.2174). Regression analyses between
the floristic and edible environments for the FSA region and three
languages, representing hunter-gatherers (Ju│’hoan), pastoralists
(Khoekhoe) and agrarians (Venda) were all significant (p <0.001)
with high R2 values (respectively 0.6181, 0.7702, 0.6654 and 0.7900), as
were the relationship (p <0.001) between what is edible and what
was actually utilised. Surprisingly, the Apocynaceae had a much higher
residual value than globally important food plant families. Vitamin C of
fruits seems to have higher levels along the coastal regions, and
carbohydrates in underground storage organs have higher levels in the
summer-arid western region. Main conclusions: There is an apparent
preference for certain food plant families in southern Africa. This
selection appears to be driven by subsistence strategy, based on the
categories of plants preferred by the three representative language
groups.