Leafy vegetables accompany
many West African dishes, such as pounded yam in the south of the region. In
collaboration with chemists from the University of Bristol, researchers from
Goethe University have now successfully shown that the origins of such dishes
date back 3,500 years.
FRANKFURT. Over 450 prehistoric pots were
examined, 66 of them contained traces of lipids, that is, substances insoluble
in water. On behalf of the Nok research team at Goethe University, chemists from
the University of Bristol extracted lipid profiles, with the aim of revealing which
plants had been used. The results have now been published in “Archaeological
and Anthropological Sciences": over a third of the 66 lipid profiles displayed
very distinctive and complex distributions – indicating that different plant species
and parts had been processed.
Today, leafy vegetables, for example the cooked leaves
of trees such as the baobab (Adansonia digitata) or of the shrubby – nomen
est omen – bitter leaf (Vernonia amygdalina), accompany many West
African dishes. These leafy sauces are enhanced with spices and vegetables as
well as fish or meat, and complement the starchy staples of the main dish, such
as pounded yam in the southern part of West Africa or thick porridge made from
pearl millet in the drier savannahs in the north. By combining their expertise,
archaeology and archaeobotany researchers at Goethe University and chemical
scientists from the University of Bristol have corroborated that the origins of
such West African dishes date back 3,500 years.
The studies are part of a project funded by the German
Research Foundation, which was headed by Professor Peter Breunig and Professor
Katharina Neumann and ended in December 2021. For over twelve years,
archaeologists and archaeobotanists from Goethe University studied the Nok
culture of Central Nigeria, which is known for its large terracotta figures and
early iron production in West Africa in the first millennium BC – although the
roots of the Nok culture in fact stretch back to the middle of the second
millennium. Research focused above all on the social context in which the
sculptures were created, that is, including eating habits and economy. Using carbonised
plant remains from Central Nigeria, it was possible to prove that the Nok
people grew pearl millet. But whether they also used starchy plants, such as
yam, and which dishes they prepared from the pearl millet had so far been a
mystery.
“Carbonised plant remains such as seeds and nutshells
preserved in archaeological sediments reflect only part of what people ate back
then," explains Professor Katharina Neumann. They hoped, she says, that the
chemical analyses would deliver additional insights into food preparation. And
indeed, with the help of lipid biomarkers and analyses of stable isotopes, the
researchers from Bristol were able to show, by examining over 450 prehistoric
pots, that the Nok people included different plant species in their diet.
Dr Julie Dunne from
the University of Bristol's Organic Geochemistry Unit says: “These unusual and
highly complex plant lipid profiles are the most varied seen (globally) in
archaeological pottery to date." There appear to be at least seven different
lipid profiles in the vessels, which clearly indicates the processing of various
plant species and plant organs in these vessels, possibly including underground
storage organs (tubers) such as yam.
Since the beginning of the project, the archaeobotanists
have sought evidence for the early use of yam. After all, the Nok region is situated
in the “yam belt" of West Africa, that is, the area of the continent in which
yam is nowadays grown. Carbonised remains are of no further help here because
the soft flesh of the tubers is often poorly preserved and mostly non-specific
as well. The chemical analyses indicate that – apart from leaves and other as
yet unidentified vegetables – the Nok people also cooked plant tissue
containing suberin. This substance is found in the periderm of both overground
and underground plant organs – possibly a first indication that yam was used,
if not the unequivocal proof hoped for.
Through the archaeobotanical study of carbonised
remains, pearl millet (Cenchrus americanus) and cowpea (Vigna
unguiculata), the oily fruits of the African elemi (Canarium
schweinfurthii) and a fruit known as African peach (Nauclea latifolia),
which due to its high number of seeds is reminiscent of a large fig, were
already known. Molecular analysis now rounds off the picture of food
preparation at the sites of the Nok culture. Archaeobotanist Dr Alexa Höhn from
Goethe University explains: “The visible and invisible remains of food
preparation in the archaeological sediment and the pottery give us a much more
complete picture of past eating habits. This new evidence suggests a significant
time depth in West African cuisine."
Publication: Julie Dunne, Alexa Höhn, Katharina Neumann, Gabriele Franke, Peter Breunig,
Louis Champion, Toby Gillard, Caitlin Walton‑Doyle, Richard P. Evershed Making
the invisible visible: tracing the origins of plants in West African cuisine
through archaeobotanical and organic residue analysis. Archaeological and
Anthropological Sciences https://doi.org/10.1007/s12520-021-01476-0
Picture download: https://www.uni-frankfurt.de/111577824
Caption: Excavation of a Nok vessel at the Ifana 3 site.
(Photo: Peter Breunig)
Further information
Dr Alexa Höhn
African Archaeology and Archaeobotany
Telephone +49 (0)69-798-32089
Email a.hoehn@em.uni-frankfurt.de
