Bronze Age herders spread farming around Asia

Nomadic herding groups that inhabited Central Asia’s mountains and deserts more than 4,000 years ago spread crops across much of Asia and took up cultivation themselves surprisingly early, a new study suggests.

The findings fit with other emerging evidence that ancient Asians flexibly mixed herding and farming lifestyles. That type of adaptability enabled agriculture to initially spread via mainland herders and coastal seafarers, not migrating farmers or trading networks of urban civilizations as anthropologists had previously thought.

Seeds recovered at two herder campsites in Kazakhstan represent the earliest evidence of the combined use of bread wheat and broomcorn millet, say anthropologist Robert Spengler of Washington University in St. Louis and colleagues. Radiocarbon dates of charred wood and seeds at these sites, Tasbas and Begash, range between roughly 4,800 and 4,300 years ago.

The findings push back the dates of the two crops’ first appearance in Central Asia, suggesting that the herders transported bread wheat from west to east and broomcorn millet from east to west. Bread wheat originated about 6,000 years ago in Southwest Asia and was transported to East Asia, but didn’t get there until at least 4,500 years ago. Broomcorn millet, which was domesticated 8,000 years ago in East Asia, turned up in Southwest Asia 4,000 years ago.

No signs of farming appear at the two camps in Kazakhstan, the researchers report April 2 in the Proceedings of the Royal Society B. The seeds mainly came from special chambers in which the dead were cremated.

“Early pastoralists in Central Asia may have obtained crops solely for burial rituals,” says Washington University anthropologist and study coauthor Michael Frachetti.

Large numbers of seeds discovered by the researchers at two other camps in Turkmenistan indicate that mobile herders ate millet, wheat, barley and green peas over 3,400 years ago. An absence of broomcorn millet at nearby farming villages suggests that herders cultivated that crop, and perhaps others, about 600 years before previous evidence of farming in Central Asia.

Spengler’s team regards these camps as herders’ seasonal outposts, not permanent, year-round settlements. “Agriculture and settled life are shown to be separate and independent activities in these new discoveries,” says David Anthony, an archaeologist at Hartwick College in Oneonta, N.Y. Anthony has directed excavations of 3,900- to 3,700-year-old settlements in Russia’s Volga steppes, where herders lived year-round. Residents there collected wild seeds but didn’t grow crops, he says.

Spengler and his colleagues provide “much needed data” showing that herding groups transported domesticated crops out of two cultivation heartlands to the rest of Asia, says Harvard University archaeologist Rowan Flad.

Ancient herding groups, each containing no more than about 20 individuals, built numerous campsites in summer and winter pastures across Central Asia, Frachetti says. Previous finds suggest that groups periodically congregated at certain summer pastures. Exchanges there led to the gradual expansion of wheat from west to east and millet from east to west, he proposes.

Distances between each group’s summer and winter pastures ranged from about 25 to 50 kilometers, he adds. Some herders may have ridden horses between camps, but little is known about how the groups traveled, Frachetti says.

Herders weren’t the only ones carrying crops from one part of the world to another, says archaeologist Dorian Fuller of University College London. In 2011, Fuller and colleagues reviewed in Antiquity archaeological evidence indicating that seafaring groups in southern Arabia ferried crops across the northwestern Indian Ocean, between what’s now East Africa and western India, starting around 4,000 years ago.

Seafarers also contributed to the westward dispersal of East Asian broomcorn millet, which reached the southern end of the Arabian Peninsula 4,000 years ago and East Africa 3,700 years ago, Fuller says.