How it began
The domestication of pearl millet has been traced to the western Sahel. Its earliest evidence as a domesticate comes from pottery tempered with millet chaff at the site of Er Negf in the Lower Tilemsi Valley of northeastern Mali, with the temper radiocarbon dated to 2579 to 2369 cal BCE. Researchers who reported the Tilemsi finds described them as the earliest archaeobotanical evidence for domesticated pearl millet, predating other finds from Africa or India by several centuries. The sites lie in present-day Mali.
Before it existed
Evidence suggests that people were already cultivating wild pearl millet as early as about 4500 BCE in the Araouane region of Mali, where wild Pennisetum chaff was used as ceramic temper. Charred wild grains have also been found at several sites across the central and western Sahara from the Early to Middle Holocene. Sherds from northern Mali dating to the fifth and fourth millennia BCE contain millet chaff with wild forms.
How it works
Researchers track domestication through three changes preserved as imprints in pottery: stalked seed clusters that no longer shatter, the appearance of paired spikelets, and larger grains. By the fourth millennium BCE average grain breadth had increased by 28 percent. In the third millennium BCE seeds were on average 38 percent wider than wild seeds and nonshattering forms appeared. Nonshattering spikelets had probably become fixed by around 2000 BCE, while grain size kept increasing into the second millennium BCE.
How it spread
Once domesticated, pearl millet spread widely and rapidly. After about 2200 BCE pearl millet farming appears to have expanded quickly into more southern savanna regions of West Africa. Grains from Bhando Qubo in South Asia have been dated to about 2576 to 2354 BCE, which suggests that the crop reached South Asia within roughly 50 to 100 years of the earliest Malian evidence.
Who pushed back
The early dates have been questioned. The Er Negf date has been considered possibly too old because older carbon may have adhered to the temper that was dated, and a grain from Karkarichinkat Nord dated to 2621 to 2464 BCE does not show clear domestication traits. The authors of the Tilemsi study themselves highlighted potential flaws in using organic chaff-tempered pottery to date pearl millet.
