Unlike many of their mostly meat-eating peers, a group of late Stone Age hunter-gatherers living in what is now northeastern Morocco had a largely plant-based diet. But despite dining for millennia on local, wild plants — such as acorns, pistachios and wild oats, the Iberomaurusians never started cultivating those plants. The finding aligns with recent challenges to scientists’ theory that heavy reliance on plants ultimately leads to their domestication (SN: 11/9/21).
Before humans figured out farming, they relied on hunting and gathering to sustain themselves, with most protein coming from animals. Over time, they shifted from foraging to cultivating certain plants, eventually leading to the plants’ domestication — so goes the typical story of agriculture’s emergence. Archaeologists once assumed that the Iberomaurusians also relied mostly on animals. But data from human remains at a site in Morocco points to a predominantly plant-based diet, researchers report April 29 in Nature Ecology & Evolution.
The site — called Taforalt, which is located in a cave — is a “very important site to study human evolution and understand human behavior during this time,” says Zineb Moubtahij, an archaeologist at Géosciences Environment Toulouse, a research laboratory in France. The Iberomaurusians lived around this area for a long time, starting around 23,000 years ago. They used part of the cave to bury the deceased.
To learn about the Iberomaurusians’ diets, Moubtahij and colleagues turned to teeth and bones from these remains, which date to between 15,077 and 13,892 years old. The team looked at levels of certain forms, or isotopes, of elements — including zinc, carbon and nitrogen — that were deposited from food into tissues and bones. The researchers also looked at isotopes in the remains of herbivores and carnivores from the site, such as sheep and foxes, and compared those to the human isotope levels.
The analysis showed that the Iberomaurusians’ diets were closer to that of herbivores, suggesting a heavy reliance on plants not animals. The group wasn’t completely vegetarian; meat was still on the menu, Moubtahij says. But compared with other hunter-gatherers from this time, the Iberomaurusians’ diet leaned more on the gatherer side and less on the hunter side.
Previous work has suggested that the Iberomaurusians loved their plant foods, says Teresa Steele, a paleoanthropologist at the University of California, Davis not involved in this study. In 2014, researchers analyzed the decayed teeth of some Iberomaurusians. Their frequent cavities indicated a diet rich in starchy, fermentable foods. But it’s “always nice to see further verification of things we have less direct evidence about,” she says.
Curiously, the group relied on wild plants for many millennia without ever domesticating them. The archaeological record suggests the plants’ features didn’t change over time.
That’s in contrast with humans in southwestern Asia, who began farming around 12,000 to 11,000 years ago (SN: 7/4/13). It wasn’t until around 7,600 years ago that agriculture arrived in what is now Morocco, and the farmed plants had been brought from other lands. Why the Iberomaurusians’ reliance on plants didn’t lead to domestication is a mystery, Moubtahij says.
Because there are relatively few well-preserved human remains from around this time in history — the late Pleistocene — scientists have limited evidence to piece together how agriculture arose in different places. “It’s really important that we have these sort of studies that show us that there were alternative pathways and food production systems,” says Michael Westaway, an archaeologist at the University of Queensland in Australia who was not involved in the work. One thing is clear: “Not all roads lead to agriculture.”
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