Human migration and trade have played a significant role in shaping the genetic makeup of chickpeas, according to a recent study published in the journal Molecular Biology and Evolution. Led by researchers Anna Igolkina of Peter the Great St. Petersburg Polytechnic University, Eric von Wettberg of the University of Vermont, and Sergey Nuzhdin of the University of Southern California, the study utilized genetic data from over 400 chickpea specimens collected in the 1920s and 1930s.
The collection included two subtypes of chickpeas, desi and kabuli, which differ in terms of color and size. Chickpea samples were obtained from nine distinct geographical regions: the northern and southern Mediterranean, Turkey, Lebanon, Ethiopia, the Black Sea, western and eastern Uzbekistan, and India. The researchers employed two novel models, popdisp (population dispersals) and migadmi (migrations and admixtures), to analyze the genetic data.
The popdisp model was utilized to understand how chickpeas spread within each geographic region. The researchers compared two scenarios: one involving the dispersal of chickpeas along routes that were historically traversed by humans, possibly trade routes, and another scenario assuming chickpeas dispersed in a linear manner, regardless of geographic barriers.
Surprisingly, the study revealed that genetic similarity among chickpea landraces in different regions was more influenced by human movement costs rather than linear distance. This suggests that the spread of chickpeas within each region primarily occurred along trade routes, rather than through simple diffusion.
The migadmi model aimed to determine the origin of the Ethiopian desi population. Previous studies had proposed two possible origins for Ethiopian chickpeas: either an Indian origin based on morphological similarities or a Middle Eastern origin due to evidence of human migration from western Eurasia to East Africa around 4,500 years ago.
The results of the study indicated that both scenarios may be accurate, as Ethiopian chickpeas share ancestry from Indian, Lebanese, and Black Sea source populations. This finding highlights the cultural connections between Ethiopians and the Middle East, as well as the importance of Indian Ocean trade routes for agricultural and cultural exchange between South Asia and East Africa.
Additionally, the migadmi model suggested that the kabuli type of chickpeas originated from a local desi chickpea population in Turkey, contradicting the linguistic suggestion that the kabuli type originated in Central Asia and was named after Kabul City in modern Afghanistan.
While this study sheds light on the natural history of chickpeas and their interconnectedness with human trade routes and migrations, its implications extend beyond chickpeas alone. The development of two new models, popdisp and migadmi, presents a valuable contribution. These models can be applied to analyze migrations and admixtures in other species, providing insights into complex migration patterns. The researchers hope that these tools will be used to investigate similar migration patterns in human-associated species such as crops, pests, and mutualists, as well as in natural species.
By unraveling the historical interactions between humans and plants, researchers can gain valuable insights into the cultural and economic exchanges that have shaped our world.
