Integrating ethnolinguistic and archaeobotanical data to uncover the origin and dispersal of cultivated sorghum in Africa: a genomic perspective

  1. Aude Gilabert
  2. Monique Deu
  3. Louis Champion
  4. Philippe Cubry
  5. Armel Donkpegan
  6. Jean-Francois Rami
  7. David Pot
  8. Yves Vigouroux
  9. Christian Leclerc

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Abstract

Archaeobotanical evidence suggests that the beginning of cultivation and emergence of domesticated sorghum was located in eastern Sudan during the fourth millennium BCE. Here, we used a genomic approach, together with archaeobotanical and ethnolinguistic data, to refine the spatial and temporal origin and the spread of cultivated sorghum in Africa. We built a probability map of the origin of sorghum domestication in Eastern Africa using genomic data and spatial Bayesian models. The origin was located in Eastern Sudan and Western Ethiopia, in perfect concordance with recent archaeobotanical evidence. Calibrated on archaeological remains, our genomic-based model suggests that the beginning of the expansion of sorghum agriculture took place around 4,600 years ago. Spread of sorghum cultivation led to a sorghum population structure fitting ethnolinguistic groups at different scales, suggesting that human social groups and sorghum populations co-diffused. Consequently, ethnolinguistic barriers and social preferences, as well as adaptation to specific climate zones, have contributed to structuring domesticated sorghum diversity during its diffusion.

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  1. Version published to 10.24072/pcjournal.613
  2. Peer Community in Evolutionary Biology

    Cross-discipline research is an increasing need in modern world just to fit societal expectations or simply to better achieve one critical aim of scientific inquiry, to know the true causes of facts, both proximate and ultimate. This is increasingly notorious in day-to-day life of researchers, as evaluation of research grants and careers considers multi-, inter- and trans-disciplinarity as items to be specifically addressed (Porter et al., 2008; Wagner et al., 2011). Whereas interdisciplinarity is also encouraged by top journals, even by those within classical scientific disciplines, most of papers are not beyond multidisciplinarity, that is, they use methods and/or approach interpretations based on those proper of each field, but results do not surpass a merely additive advance. True interdisciplinarity means that results obtained lay far beyond those obtained by the single disciplines composing the study. Complex questions need also complex approaches. This is a difficult aim since methods should be properly linked (Lynch, 2006). Here we recommend a genuine interdisciplinary paper (Gilabert et al. 2025).
     
    In natural sciences, it should be admitted that interdisciplinarity is more easily adopted in some specific fields which rapidly ask for support from the social sciences. This is for example the case of ecology and evolutionary biology. Serve as already classical and nearly synchronous examples, the interplay between human population genetics and linguistics (Cavalli-Sforza, 1997), or between ecology and history of human societies (Diamond, 1997), which have percolated so profoundly in the social sciences that they are currently established their own research programmes. Gilabert et al. (2025) have managed to use methods from three disciplines (archaeology, linguistics, and crop domestication and expansion by artificial and cultural selection). One can imagine of a similar study using solely modern phylogeographical tools for depicting migration routes of cultivated sorghum and then interpreting results using the available information from other fields. Instead, the authors use also available information on the relationships among languages (closely related in pursuit and methodology to evolutionary biology, with a different target) of societies that use races of this crop, and archaeological remains to date genomic phylogeography, similar to the use of fossils for dating phylogenies. This multiple approach mighty revealed the routes of crop expansion through time and confirmed the geographic origin of the domestication formerly proposed with more classical, archaeological procedures. One of the reviewers suggested the use of another technique for depicting these expansion routes, which apparently produces more resolution and better visualization of the timing and spread of the process, although it relies on additional information on the dates of the process. Not being a molecular phylogenetist myself, it is easy to recognize that this and other tools will throw more light in the near future, due the rapid development of these techniques and the power of the data acquired by the authors. 
     
    Despite that authors claim their study as multidisciplinary I think they are very modest as it accomplishes required conditions to be interdisciplinary. As much, a multidisciplinary study would ascertain congruence between the three different approaches (linguistics, archaeology, genomic phylogeography); instead, there is a clear integration of methods and data from these in a single analytical procedure. Thus, the results transcend from single congruence. This paper paves the way for future use of even more data and information from other sources, some of them already mentioned by the authors. These may include (1) the relationship between human groups beyond those ascertained through language relationships, as done by Tao et al. (2023), cited by authors; (2) the effect of changing paleoclimates during the period revealed in this paper within the Holocene using available data and maps (e.g., Joussaume & Taylor, 2000; http://pmip.lsce.ipsl.fr/); and (3) the relationship between current crops and archaeological crop remains with the possible use of ancient DNA (Brown et al. 2015). This will prove the development of the emerging field of phyloculture reconstruction, using crops as a model system.
     
     
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    Gilabert A., Deu M., Champion L., Cubry Ph., Donkpegan A. Rami J.F., Pot D., Vigouroux Y., Leclerc Ch. (2025). Integrating ethnolinguistic and archaeobotanical data to uncover the origin and dispersal of cultivated sorghum in Africa: a genomic perspective. bioRxiv, ver.1 peer-reviewed and recommended by PCI Evolutionary Biology. https://doi.org/10.1101/2025.04.16.648676

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  3. Version published to 10.1101/2025.04.16.648676 on bioRxiv