by Prehistoric humans are often believed to have eaten mostly meat – to the extent that proponents of many modern low-carb diets show that they closely resemble the eating style of “prime” humans.
But a recent excavation at a cave in Taforalt, Morocco, complicates this picture, according to findings published Monday in Nature Ecology & Evolution.
These findings “challenge the prevailing notion” that prehistoric humans “relied heavily on animal proteins,” the authors wrote.
Their findings also suggested that a plant-based diet has a strong advantage: It makes it easier to wean young children. This factor gives a strong additional advantage to the transition to settled agriculture.
By analyzing 13,000-year-old body teeth found in caves in Morocco, researchers at the Max Planck Institute in Leipzig, Germany, found evidence of “substantial plant-based” elements in their diet.
The researchers found this out by analyzing the respective levels of the element zinc in the teeth of the bodies found at the site.
Zinc has many isotopes — or forms with the same number of protons but different numbers of neutrons, and therefore different weights. The breakdown of the plant fiber body tends to leave it with a higher ratio of the heavier zinc isotopes than meat processing.
The zinc levels in the human teeth recovered from Taforalt were much closer to those seen in Barbary sheep recovered from the site – that is, pure herbivores – than they were to the levels of local canids such as wolves, jackals and dogs.
Although the canid teeth found at the site showed that they were not pure carnivores either, they seem to have supplemented meat in their diets with fruit.
The people weren’t pure herbivores either – the sheep bones found at the site had cut marks, suggesting they had been hunted, butchered and processed.
But the isotopic analysis suggests that people at the site got only about 50 percent of their diet from meat, including gazelles, wild cattle and hartebeest.
They supplemented this with sweet acorns, pine nuts and legumes – which they apparently made into flour with grinding stones found at the site. (The starches from these plants left cavities in their teeth.)
They seem to have gathered plants in periods of seasonal abundance and stored them on site to eat throughout the year — a step between foraging and agriculture — probably during periods when animal protein was less available.
The isotope analysis also allowed the scientists to determine how old the people buried in the isolated caves were – or weaned them off breast milk and onto solid foods – and what diet they switched to.
They found something else surprising while doing this: The evidence from the teeth showed that babies were weaned early – before they were even a year old – and perhaps “with plant-based foods .”
The researchers admitted that it was difficult to reach firm conclusions in this regard, since they had such a small sample size to work with. But their findings may indicate the use of starchy grains as a means of weaning babies — a practice that would be in stark contrast to that of many hunter-gatherer societies, “where extended breastfeeding periods due to limited availability of suitable weaning foods,” the authors noted.
The infant bodies in the cave suggest that this transition involved a tough trade-off: Early weaning in the past may have meant “increased infant stress and mortality,” the researchers wrote.
But by significantly reducing the time required for breastfeeding, the study shows that the practice could also significantly reduce the time between births – allowing plant-eating populations to grow faster, and hunter-gatherers eventually pushed to the edges.
In recent years, research has made less of a distinction between farming and foraging, instead uncovering a more diverse spectrum of feeding behaviors: Ancient humans gathered, foraged, processed and stored plant-based foods long before the development of captive food , engineered by man. plant species that we formally call agriculture.
Where that formal transition did occur, recent research suggests that it was the result of an ecological crisis. In south-west Asia, thought to be the center of agriculture in the West, declining populations of large and medium-sized game animals led hunters to diversify their diets.
One explanation for the rise of farming in this region is that it arose from the so-called Broad Spectrum Revolution — as rising populations and climate change pressured human populations on the number of prey and plant species they ate. they increase much more widely than it was. maybe her ancestors would.
But in northwest Africa, despite reliance on wild plants and close genetic links to proto-farmers in southwest Asia, prehistoric humans did not develop farming. The first evidence of farming in the region – a single domesticated lentil seed – does not appear for another 7,500 years after the abandonment of the cave sites on which Monday’s study was based.
Planck scientists can only point out the “difference” between these two regions – they cannot explain it. They note that as the climate continued to cool under the long glacial expansion known as the Younger Dryas, plant resources became less available, and the cave sites where they conducted their research became increasingly empty. more.
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