Studying Prehistoric Diets

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Ann Gibbons wrote in National Geographic: “Until agriculture was developed around 10,000 years ago, all humans got their food by hunting, gathering, and fishing. As farming emerged, nomadic hunter-gatherers gradually were pushed off prime farmland, and eventually they became limited to the forests of the Amazon, the arid grasslands of Africa, the remote islands of Southeast Asia, and the tundra of the Arctic. Today only a few scattered tribes of hunter-gatherers remain on the planet. [Source: Ann Gibbons, National Geographic, September 2014 /*/]

“That’s why scientists are intensifying efforts to learn what they can about an ancient diet and way of life before they disappear. “Hunter-gatherers are not living fossils,” says Alyssa Crittenden, a nutritional anthropologist at the University of Nevada, Las Vegas, who studies the diet of Tanzania’s Hadza people, some of the last true hunter-gatherers. “That being said, we have a small handful of foraging populations that remain on the planet. We are running out of time. If we want to glean any information on what a nomadic, foraging lifestyle looks like, we need to capture their diet now.” /*/

“So far studies of foragers like the Tsimane, Arctic Inuit, and Hadza have found that these peoples traditionally didn’t develop high blood pressure, atherosclerosis, or cardiovascular disease. “A lot of people believe there is a discordance between what we eat today and what our ancestors evolved to eat,” says paleoanthropologist Peter Ungar of the University of Arkansas. The notion that we’re trapped in Stone Age bodies in a fast-food world is driving the current craze for Paleolithic diets. The popularity of these so-called caveman or Stone Age diets is based on the idea that modern humans evolved to eat the way hunter-gatherers did during the Paleolithic—the period from about 2.6 million years ago to the start of the agricultural revolution—and that our genes haven’t had enough time to adapt to farmed foods.” /*/

Laurence A. Marschall wrote in Natural History magazine:” Despite the highly technical character of paleontological research, the subject of ancient diets is one of great popular interest today, driven in part by current, widespread thinking that we are what we eat. Yet, readers looking for the proper diet—a “paleo,” or “natural,” match to our biology—will be disappointed. The “biospheric buffet” of every age and every locale is different, which is what the research shows. Nature’s menu, like that of a high-end restaurant, reflects what’s available on a given day in forest, field, and farm. [Source: Laurence A. Marschall, Natural History magazine, May 2017]

Studying Teeth to Gain Information About Diet

Studying teeth — which fortunately are among the more common hominin fossils — offers a lot information about diet and the foods hominin ate especially with the technology and science available today. "The moment we get our adult teeth, they start to wear down. And the rate at which they wear down is very much related to what you eat — especially if you look at the molars," Sireen El Zaatari, a paleoanthropologist at the University of Tübingen in Germany, told NPR. "This food that you're chewing is leaving tiny, tiny marks on your teeth." [Source: Maanvi Singh, NPR, April 29, 2016 \~/]

“Meat — especially cooked meat — is relatively gentle on the chompers, whereas seeds and nuts leave a mark, she says. El Zaatari and her colleagues looked at the teeth of Neanderthals and humans living mainly in Europe throughout the Upper Paleolithic period. "A better way to look at diet is to look at the chemistry of [tooth] enamel," Cachel says. \~/

“Different plants absorb different amounts of carbon isotopes. Scientists can analyze the ratios of various isotopes on ancient enamel to figure out what sorts of fruits, nuts and vegetation our ancient predecessors ate. So the isotopes in tooth enamel can paint a broad picture of what someone ate throughout their life. On the other hand, "the advantage of looking at [dental wear] is that you get a fuller picture of what all they were eating right up to the time when they died," says Shara Bailey, an anthropologist at New York University.” \~/

On a study involving the teeth of several Australopithecus species, Melissa Hogenboom of the BBC wrote: “Their diet was analysed from the chemical make up of their teeth, identifying the carbon isotopes within them. The ratios of different types of carbon atoms, or isotopes, in fossils can give clues to what a fossil creature ate because different foods have different carbon isotope signatures. “What we have is chemical information on what our ancestors ate, which in simpler terms is like a piece of food item stuck between their teeth and preserved for millions of years,” said Dr Zeresenay Alemseged, from the California Academy of Sciences, co-author on two of the papers. “Because feeding is the most important factor determining an organism’s physiology, behaviour and its interaction with the environment, these finds will give us new insight into the evolutionary mechanisms that shaped our evolution.” [Source: Melissa Hogenboom, BBC News, June 4, 2013]

Studies of Chemical Isotopes in Tooth Enamel

Acorns were eaten by prehistoric humans

Zach Zorich wrote in Archaeology magazine: “Direct evidence that reveals the behavior of the human race's earliest ancestors has been all but impossible for paleoanthropologists to find. Now, however,studies of chemical isotopes in tooth enamel are providing new lines of evidence concerning the lives of early hominins. As tooth enamel forms during the first eight years of life, it absorbs chemicals from the food and water that people consume and, indirectly, from the bedrock in the area where they reside. That chemical signature provides an important record of an individual's life, which scholars are now learning to read. Two recent isotope studies are changing paleoanthropologists' understanding of hominins who lived roughly 2.2 to 1.4 million years ago. [Source: Zach Zorich, Archaeology, Volume 64 Number 5, September/October 2011 ***]

“A study published in Proceedings of the National Academy of Sciences examined the amounts of carbon isotopes in two Paranthropus boisei teeth from eastern Africa. Carbon isotopes reveal details about diet, and the research showed that these individuals dined on grasses and sedges. Previously, P. boisei had been nicknamed Nutcracker Man because paleoanthropologists believed the species' large teeth and powerful jaws were an evolutionary adaptation to eating hard foods. ***

“A second study, published in the journal Nature, measured strontium isotopes in the teeth of Australopithecus africanus and Paranthropus robustus from southern Africa. Strontium isotopes offer evidence of the bedrock in an individual's early home area because plants and water absorb strontium from the bedrock, which is then absorbed by tooth enamel. This study showed that females of both species tended to grow up in areas with a different type of bedrock than the places where their teeth were ultimately found. The finding could indicate that females left the social groups they were born into and moved away to live with their mates. ***

“The major impact of this research has less to do with the results of the two studies and more to do with providing paleoanthropologists with a new research tool, according to the University of Colorado's Matthew Sponheimer, who took part in both projects. "If we can be clever enough, we might be able to design ways to get at interesting behaviors that had seemed forever lost," he says.” ***

Studying Teeth Tartar — Dental ‘Calculus’ — of Hominins

Chris Gorski wrote in Inside Science: “Many ancient human teeth, including specimens tens of thousands of years old, still hold onto tiny pieces of food — and even bacteria. Anthropologists are studying the tartar attached to ancient human teeth to learn more about the plants people ate and the pathogens they carried long ago. Tartar, also known as dental calculus, is a hard substance that toothpaste ads promise to obliterate and dentists scrape away. It builds up on human teeth after dental plaque solidifies. A dentist might scrape away 30 milligrams of a patient’s calculus each visit. Sets of teeth from hundreds or thousands of years ago might have up to 20 times that much, a mass roughly equal to a small paperclip. [Source: Chris Gorski, Inside Science, May 30, 2012 /]

“Scientists are only beginning to explore the variety of materials caught in calculus, which preserves organic materials that are often fleetingly preserved in other settings. This allows scientists to address questions that are very difficult to answer using established archaeological methods. “There are so many time periods in human history where we have theories about what they ate but we really have no idea,” said Amanda Henry, a physical anthropologist at the Max Planck Institute for Evolutionary Anthropology, in Leipzig, Germany. /

“Seeds and grains often degrade slowly and animal bones typically last even longer. But finding direct evidence of vegetable consumption is more difficult. Vegetables such as cabbage and carrots were important foods in medieval Europe, but evidence to confirm their consumption is hard to come by. Reconstructing the full diet for people living in earlier periods is even more difficult. “We know very little about the vegetable and salad portion of the diet,” said Christina Warinner, an archaeological geneticist at University of Zurich’s Centre for Evolutionary Medicine, in Switzerland. “[Studying calculus] could potentially be an entirely new way of approaching that.”“ /

Teeth from different hominins

Methodology of Studying Hominin Tooth Tartar

Chris Gorski wrote in Inside Science: “Calculus contains pollen grains and microscopic fossilized plant pieces called phytoliths, in addition to starch grains and even bacteria. Fragments of bacterial DNA found in calculus can help identify specific pathogens that were once present in the mouths of ancient people. The plant evidence can be definitive enough to suggest the species that was consumed, or it may suggest what part of a plant was eaten, such as a fruit or leaf. This can help track the use, spread and evolution of food plants, including agricultural varieties, through time and space. Researchers can examine the calculus directly on the tooth with a microscope. But for further analysis, they carefully scrape the material off ancient teeth with common dental tools to avoid contaminating the samples with modern material. From that scraped-off tartar, they then carefully remove non-organic material to concentrate the food remnants. [Source: Chris Gorski, Inside Science, May 30, 2012 /]

“Scientists use microscopes and molecular methods to examine the samples....Techniques to deduce ancient diets and disease from dental calculus are still being established and verified. Molecules of DNA in dental calculus are often degraded, and the more time has passed, the lower the chance that the sample is pristine, which makes interpretation more complicated. Scientists are also uncertain as to how comprehensively calculus can portray diet. Not all foods that are consumed will be found in calculus. Although finding evidence that a food was in a person’s mouth is significant, it doesn’t necessarily explain how often the food was eaten, or what proportion of the overall diet it represented. “We must be conscious that ancient people did not only eat starchy seeds or tubers; they also ate leaves, flowers, and so on,” said Pagan-Jimenez. What percentage of a person’s diet is represented in that record? We don’t know,” said Henry. “Any technique, you need to work out all the bugs before all academics buy it. /

“Scientists are still forming a full picture of all the components found inside ancient dental calculus, said Warinner. Henry said she planned to examine calculus “for other kinds of plant residues or even animal food residues.” She said that the technique may help solve an important mystery: when humans began cooking their food — answers currently range from a few hundred thousand to more than 1.5 million years ago. /

Kinds of Information Found in Tooth Tartar

Chris Gorski wrote in Inside Science: “Examining the small bits of food they find is challenging some long-held beliefs about ancient peoples and helping to answer significant questions. Henry has been studying Neanderthal diet and working to confirm her initial results that they ate plants regularly. Some researchers have long argued that Neanderthals were primarily carnivores who depended on meat and fat. “We were able to show that [Neanderthals] did eat plant foods and they processed these foods,” said Henry. “It’s the first time we have evidence of what those plant foods are.” “Henry and her collaborators identified grass seeds, tubers that may have been related to water lilies, and at least in a location in present-day Iraq, the foods had been cooked. [Source: Chris Gorski, Inside Science, May 30, 2012 /]

“Jaime Pagan-Jimenez, a Puerto Rico-based anthropologist working at Leiden University in the Netherlands, recently began analyzing calculus to obtain more evidence in his study of diets throughout the Caribbean islands. Pagan-Jimenez had already studied starch grains found in artifacts used to process and cook foods, concluding that the people who first lived on the Caribbean islands were, in at least many cases, cultivating a variety of food plants, such as corn, sweet potato, beans, and more. His findings also challenged the idea that the area’s main food crop was manioc, a root also known as cassava or yucca. The new technique allows him to confirm what foods actually reached the mouth. “We had the chance of seeing directly in the human tooth what plants they were eating at different time periods and sub-regions in the Caribbean islands,” Pagan-Jimenez wrote to Inside Science in an email. That evidence changes the interpretation of other archaeological findings. “It turns out that these tools that we’ve called manioc scrapers were not at all used for processing manioc,” said Henry. /

“Starch grains, such as those found in cooking pots, are well-established evidence of food processing and consumption. Scientists also look for clues about food consumption in the atomic makeup of bones and tooth enamel. However, calculus allows researchers to attain a greater level of detail. “For starch grains studies in archeology, human dental calculus is the last piece of the ‘broad picture’ for acquiring direct information on the whole process of plant preparation and consumption as food,” said Pagan-Jimenez.

Health Information Gleaned from Dental ‘Calculus’

Chris Gorski wrote in Inside Science: “Dental plaque contains all manner of information about an individual’s health. It can contain clues about tuberculosis, stomach ulcers and more. Since calculus is formed from plaque, it seemed natural to Warinner to investigate the preservation of health information. “It seems like a great way to actually access so much health information about ancient peoples that otherwise has been really, really hard to do,” said Warinner. /

“One significant modern change is a highly processed diet, which is often accompanied by fluoridated water. How does the state of modern people’s mouths differ from that of their ancestors? Because calculus can preserve oral bacteria, it opens new doors to scientists. “One of the things we don’t know very well is what actually is our natural or ancestral state of health in our mouth,” said Warinner. “We can look at specific dental diseases and try to understand how they have changed over time.” [Source: Chris Gorski, Inside Science, May 30, 2012 /]

Warinner said that in addition to bacteria from the mouth, calculus also contains bacteria that originated in other areas of the body. These bacteria can provide more information on the array of tiny organisms that inhabit the human body, called the microbiome. Doctors are becoming increasingly aware of the relationship between this collection of flora and human health. Data gathered from genetic material found in samples such as calculus is termed metagenomic, and can greatly enhance scientists’ ability to research the historical microbiome. “[Calculus] allows us unparalleled access to these more distant organ systems that we’ve almost never had access to in the archaeological record except in some exceptional circumstances,” said Warinner. /

““The idea that metagenomic data from archaeological dental calculus can provide a glimpse of ancient human diet and health is very clever, and if validated, it will be a very exciting discovery!” wrote Cecil Lewis, a molecular anthropologist at the University of Oklahoma, in an email. /

Teeth found in Fuyan Cave in China

Stable Isotope Analysis

Research published in April 2024 in the journal Nature Ecology & Evolution on the Iberomaurusians, hunter-gatherers who buried their dead in Taforalt cave in what’s now Morocco between 13,000 and 15,000 years ago, adds determined that the perhistoric Moroccans ate mainly plants by analyzing chemical signatures preserved in bones and teeth belonging to at least seven different Iberomaurusian using a technique called stable isotope analysis.[Source: Katie Hunt, CNN, April 30, 2024]

According to CNN: Nitrogen and zinc isotopes (variants of an element) contained in collagen and teeth enamel can reveal the amount of meat ancient diets once contained, while carbon isotopes can shed light on whether the main source of protein was meat or fish. “Humans consume these foods and the isotope information is recorded in tissues like bones and teeth,” Moubtahij said. “By analyzing this tissues that we find in archaeological records, we can know if a person ate more meat or they ate more plant-based food.”

The isotope technique shows the amount of plants eaten but not the type. However, botanical remains of charred sweet acorns, pistachio, pine nuts, wild oats and pulses discovered at the site support the information gleaned from the human remains. Grinding stones unearthed at the site also suggest plant processing took place nearby.

Was Digesta an Important Source of Food?

Raven Garvey wrote: One of the things that has come to trouble me about attempts to test related hypotheses using archaeological data — some of my own attempts included — is that they assume plants and animals are mutually exclusive food categories. Everything rests on the idea that plants and animals differ completely in how risky they are to obtain, their nutrient profiles and their abundance on a landscape. It is true that highly mobile large-game species such as bison, caribou and guanaco (a deer-sized South American herbivore) were sometimes concentrated in places or seasons where plants edible to humans were scarce. But what if people could get the plant portion of their diets from the animals themselves? [Source: Raven Garvey, Associate Professor of Anthropology, University of Michigan, The Conversation, May 30, 2023]

The plant material undergoing digestion in the stomachs and intestines of large ruminant herbivores is a not-so-appetizing substance called digesta. This partially digested matter is edible to humans and rich in carbohydrates, which are pretty much absent from animal tissues. Conversely, animal tissues are rich in protein and, in some seasons, fats — nutrients unavailable in many plants or that occur in such small amounts that a person would need to eat impractically large quantities to meet daily nutritional requirements from plants alone.

If past peoples ate digesta, a big herbivore with a full belly would, in essence, be one-stop shopping for total nutrition. To explore the potential and implications of digesta as a source of carbohydrates, I recently compared institutional dietary guidelines to person-days of nutrition per animal using a 1,000-pound (450-kilogram) bison as a model. First I compiled available estimates for protein in a bison’s own tissues and for carbohydrates in digesta. Using that data, I found that a group of 25 adults could meet the U.S. Department of Agriculture’s recommended daily averages for protein and carbohydrates for three full days eating only bison meat and digesta from one animal. Among past peoples, consuming digesta would have relaxed the demand for fresh plant foods, perhaps changing the dynamics of subsistence labor.

Ethnographically documented foragers did routinely eat digesta, especially where herbivores were plentiful but plants edible to humans were scarce, as in the Arctic, where prey’s stomach contents was an important source of carbohydrates. I believe eating digesta may have been a more common practice in the past, but direct evidence is frustratingly hard to come by. In at least one instance, plant species present in the mineralized plaque of a Neanderthal individual’s teeth point to digesta as a source of nutrients. To systematically study past digesta consumption and its knock-on effects, including female hunting, researchers will need to draw on multiple lines of archaeological evidence and insights gained from models like the ones I developed.

Image Sources: Wikimedia Commons

Text Sources: National Geographic, New York Times, Washington Post, Los Angeles Times, Smithsonian magazine, Nature, Scientific American. Live Science, Discover magazine, Discovery News, Ancient Foods ancientfoods.wordpress.com ; Times of London, Natural History magazine, Archaeology magazine, The New Yorker, Time, Newsweek, BBC, The Guardian, Reuters, AP, AFP, Lonely Planet Guides, “World Religions” edited by Geoffrey Parrinder (Facts on File Publications, New York); “History of Warfare” by John Keegan (Vintage Books); “History of Art” by H.W. Janson (Prentice Hall, Englewood Cliffs, N.J.), Compton’s Encyclopedia and various books and other publications.

Last updated April 2024