When marriage is good for your genes
06 February 2012
Botany researchers recently published a paper in the Proceedings of the National Academy of Sciences of the USA showing that marriages within small farming communities in Africa may influence the genetic diversity of manioc, a crop cultivated pantropically for its starchy, edible root often referred to as cassava. Marc Delêtre, Doyle McKey and Trevor Hodkinson analyzed how crop landraces are
passed on from one generation to the next, using the example of manioc
in Bantu societies of Gabon, central Africa. They collected and genotyped varieties grown in 10 communities in Gabon, and found that the genetic diversity of manioc clustered into distinct geographic regions, with the greatest diversity found in the southern part of the country, and the lowest diversity in the north. The authors suggest that regional differences in diversity may reflect in part the different marital practices in the two regions: in the south, where societies are matrilineal (i.e., children take the clan of their mother), a new bride moves to her husband's village and brings along manioc varieties from her mother's farm, whereas in the north, where societies are patrilineal (i.e., clan membership is inherited from the father), new brides move empty-handed and receive manioc varieties from their mothers-in-law. The result is that in patrilineal societies there is no inflow of manioc cuttings accompanying the inflow of women. According to the authors, understanding the relationship between marriage exchanges and inter-generational transmission of crop seeds may help decipher geographical patterns of crop diversity.
For full detail see:
Marc Delêtre, Doyle B McKey, and Trevor R Hodkinson (2011) Marriage exchanges, seed exchanges, and the dynamics of manioc diversity. Proceedings of the National Academy of Sciences of the United States of America 108: 18249-18254.