Ancient Humans Ate Meat!
Eben van Tonder
15 July 2023
Introduction
Earliest humans ate mainly meat. Incorporating plant food into our diet is a recent development. I summarise the landmark work of Miki Ben-Dor, Ran Barkai, and Raphael Sirtoli on the subject which is, in my opinion, the best in existence. In preparation for reading their work, I read the 1970s work of Walter L. Voegtlin. I included the parts of his work that were of the biggest interest to me.
Ben-Dor and his colleagues delve into the dietary practices of ancient humans and conclude that meat consumption played a primary role, especially during the Pleistocene era, approximately 2.58 million to 11,700 years ago. The 11700 time is significant as it brings us to the point of the agricultural revolution.
People often refer to the fact that a diverse diet of plants and meat was part of the ancient hunter-gatherer communities. Ben-Dor’s team challenges the method of directly comparing ancient human diets to those of contemporary hunter-gatherers, advocating instead for a more nuanced analysis that incorporates genetic, metabolic, and archaeological evidence. This method reveals a dietary evolution that is far from linear, shaped significantly by environmental shifts and technological progress.
Ultimately, the combined insights from Ben-Dor, Barkai, Sirtoli, and Voegtlin highlight the intricate and dynamic nature of human dietary patterns over the millennia, influenced by a confluence of ecological conditions, technological innovations, and societal shifts. This comprehensive approach not only challenges oversimplified historical dietary models but also sheds light on the remarkable adaptability of humans and the complex relationship between diet and evolutionary change.
Evidence from Ben-Dor
The overwhelming evidence is that the earliest humans consumed mostly meat and it was not till the advent of the agriculture revolution when we started incorporating more plant matter into our diets. Here is a summary of their “pieces of evidence” to this conclusion.
- Bioenergetics: Humans require significantly more energy than most primates due to our large brains, extensive tool use, prolonged child care, and learning activities. Meat provides a more efficient energy source than plants, offering a higher energy return for the effort expended in hunting compared to the continuous gathering of plants. This efficiency in energy acquisition likely influenced early humans to favour hunting, especially during periods when plant resources were scarce.
- Diet Quality: The human brain is exceptionally large, necessitating a diet rich in high-quality, calorie-dense foods. Animal fat, being more calorie-dense than proteins or carbohydrates, playd a crucial role in meeting these energy demands. Plant-based diets often contain antinutrients that can inhibit nutrient absorption, making animal products a preferred source for supporting brain development.
- Higher Fat Reserves: Humans can store more fat than our ape relatives, providing a vital energy reserve during food shortages. This capacity for fat storage, enabling prolonged fasting periods without significant muscle loss, is supported by our efficient shift into ketosis, a metabolic state where fat is burned for energy.
- Ketosis and Fat Adaptation: Humans are adept at entering ketosis, a metabolic state that serves as an alternative energy source when carbohydrates are scarce. This ability to rapidly switch to ketosis, conserving energy and sustaining physical activity during periods of low food intake, highlights a significant evolutionary adaptation for energy efficiency.
- Omega-3 Oils Metabolism: The theory that early human brain development was supported by the consumption of aquatic foods rich in DHA is debated. Alternatives, such as terrestrial animal organs or the biosynthesis of DHA from plant sources, along with genetic adaptations improving DHA conversion, suggest a flexible dietary strategy. This includes the potential for aquatic resource reliance or efficient plant-derived DHA synthesis, highlighting the dietary diversity of early humans.
- Late Genetic Adaptation to Underground Storage Organs (USOs): Recent genetic adaptations in some populations to high-starch diets from roots and tubers suggest a later incorporation of USOs into the human diet. These adaptations, enhancing metabolism and detoxification of plant glycosides, indicate that USOs might not have been a primary food source until more recent stages of human evolution.
- Stomach Acidity: High levels of stomach acidity in humans, comparable to obligate scavengers, suggest an evolutionary adaptation for consuming scavenged food with a higher risk of pathogen exposure. This trait underscores the complexity of early human diets, which likely included scavenging alongside hunting and gathering.
- Gut Morphology: The human digestive system, characterized by a smaller colon and a longer small intestine, is optimized for the digestion of fats and proteins rather than fermenting plant fibres. This adaptation suggests a dietary shift towards energy-dense, nutrient-rich animal sources, reducing reliance on plant fibre.
- Reduced Mastication and Cooking Hypothesis: The evolution of smaller jaws and teeth in humans, reducing the need for extensive chewing, points to a diet comprising softer, cooked foods or increased meat consumption. The advent of cooking, which makes food easier to chew and nutrients more accessible, likely played a significant role in dietary evolution, supporting a shift towards meat and possibly making plant foods more palatable.
- Postcranial Morphology: Human anatomical adaptations, such as increased body size and endurance running capabilities, indicate an evolution towards efficient hunting. These morphological changes, including features suited for long-distance tracking and throwing capabilities, suggest a significant dietary shift towards carnivory, highlighting the importance of meat in human evolution.
- Nutrient Density of Animal-Sourced Foods: Animal foods pack a nutritional punch not found in plant foods, offering essential nutrients like vitamins A, K2, B9, B12, B6, D, heme iron, and omega-3 fatty acids. This makes animal products both qualitatively and quantitatively superior, providing nutrients in forms readily usable by the human body.
- AMY1 Gene and Starch Consumption: The AMY1 gene, which affects salivary amylase production for starch digestion, varies among populations based on their starch consumption. Higher AMY1 copy numbers in populations with starchy diets contrast with Neandertals and Denisovans’ baseline, suggesting evolutionary dietary shifts in Homo sapiens post-divergence from these groups. Despite speculation, no direct link between AMY1 copy number and obesity or diabetes risks has been firmly established.
- Archaeological Evidence on Human Diets: Indications of plant and animal consumption in the Paleolithic era come from various sources. While plant remains are less visible in the archaeological record, evidence from tool use-wear and dental analysis suggests broad plant consumption. Stone tools reveal a shift towards increased plant processing in later periods. Zooarchaeology points to a diet rich in meat, with early humans engaging in hunting and scavenging. Isotopic analyses further support a high reliance on animal sources, with shifts in dietary practices over time reflecting ecological adaptations.
- Mesolithic Diets and Isotope Analysis: Isotope analysis shows a continued carnivorous diet into the Mesolithic, albeit with a reduction in trophic levels. The increased evidence for aquatic resource consumption in later periods suggests an adaptation to declining terrestrial animal availability, highlighting dietary flexibility in response to environmental changes.
- Trace Elements in Diet Determination: Utilizing trace elements offers insights into early human diets, suggesting a carnivorous dietary pattern among early Homo species. This method, reinforced by recent advances, supports the view of early humans occupying a high trophic level.
- Dental Pathology and Diet: The rarity of dental caries in early human remains suggests low carbohydrate consumption, indicating a diet primarily based on animal sources. The increase in caries post-agriculture marks a significant dietary shift towards higher carbohydrate intake.
- Dental Wear Analysis: While dental wear analysis provides some insights into diet, it has limitations in specifying the exact nature of consumed foods. Increased plant consumption in the Upper Paleolithic is inferred from a combination of dental wear patterns and archaeobotanical evidence.
- Behavioural Adaptations: Comparative studies suggest humans share more behavioural similarities with carnivores than primates, especially in social organization, cooperative hunting, and food sharing. These adaptations, alongside physiological traits, support early human adaptation to carnivory and a high trophic level diet.
- Paleontological Evidence: The decline in the mean body weight of terrestrial mammals during the Pleistocene, possibly influenced by human predation, suggests early humans played a significant role in their ecosystems as members of the hypercarnivore guild, impacting prey populations and competing with other carnivores.
- Zoological Analogy: Present-day predator guilds provide analogies for Paleolithic human diets, with characteristics of hypercarnivores suggesting early humans specialized in hunting large prey. This specialization required advanced hunting skills and social organization, paralleling behaviours seen in large social carnivores.
- Ethnography: Ethnographic analogies, while informative about human social and behavioural patterns, caution against direct comparisons for dietary practices due to significant ecological and technological changes since the Paleolithic. The technological and subsistence strategies observed in 20th-century hunter-gatherers may offer better insights into the Upper Paleolithic rather than earlier periods, reflecting adaptations to changing environments and prey availability.
Transition from Bendor na Voegtlin
Building on the insights from Ben-Dor and Voegtlin, we find a compelling narrative that human dietary evolution and biological adaptation have been significantly influenced by a meat-centric diet. This perspective, grounded in archaeological, biological, and paleontological evidence, suggests that early humans evolved with dietary practices that leaned heavily towards carnivory.
Voegtlin (1975), in “The Stone Age Diet,” delves into the intricacies of the digestive system, focusing on carnivores like dogs to illustrate the efficiency of a meat-dominated diet. He emphasizes the role of hydrochloric acid in the stomach for dissolving fats and proteins, a trait shared with humans, suggesting an evolutionary predisposition towards meat consumption. This digestion process is highly efficient, with carnivores—and by extension, early humans—being able to extract nearly all nutritional content from their meat-based diet.
The production of digestive enzymes by the pancreas, stimulated by the presence of chyme in the duodenum, facilitates the breakdown of food into absorbable components. Voegtlin highlights the critical role of bile in digesting fats, pointing out the evolutionary adaptation of storing bile in the gallbladder for use when needed, indicating periods of high-fat consumption typical in a carnivorous diet.
The efficiency of this digestive process is further underscored by “balance studies” mentioned by Voegtlin, which show minimal loss of ingested fat and protein in excreta. This indicates that early humans, with their similar digestive tract, could have thrived on a diet rich in animal products, utilizing nearly all the ingested nutrients effectively.
Furthermore, Voegtlin discusses the antimicrobial properties of the stomach’s hydrochloric acid, which ensures a mostly sterile digestive system, except for the large intestine where specific bacteria aid in vitamin formation. This aspect of digestion underscores the adaptability of the human body to a diet that minimizes the risk of infection from consumed food, particularly important in a diet that includes raw or minimally processed meat.
The narrative built by Ben-Dor and Voegtlin collectively paints a picture of human evolution closely tied to meat consumption. From the efficiency and safety of meat digestion highlighted by Voegtlin to the broader evolutionary and ecological implications discussed by Ben-Dor, it’s clear that meat has played a central role in shaping our biological and cultural heritage. This meat-centric dietary perspective offers valuable insights into the nutritional foundations that have supported human development and survival across millennia.
The exploration of human dietary evolution reveals a nuanced understanding of our biological and cultural adaptation to various food sources. From Ben-Dor’s archaeological and paleontological evidence to Voegtlin’s detailed examination of digestive processes in carnivores and herbivores, a comprehensive narrative emerges, illustrating the significant role of meat consumption and the efficiency of meat digestion in human evolution.
Carnivores: A Model of Efficiency
Voegtlin (1975) provides an in-depth look at the carnivore’s digestive system, using dogs as a model. He emphasizes how carnivores’ stomachs utilize hydrochloric acid to break down fats and proteins, allowing for rapid, efficient digestion and absorption. This process, characterized by minimal reliance on microbial digestion and a high absorption rate, leaves little waste, showcasing the digestive tract’s adaptation to intermittent, meat-rich diets.
Herbivores: Complexity and Microbial Dependence
In contrast, Voegtlin explores the herbivore’s digestive system, such as sheep, highlighting the complexity and reliance on microbial activity for breaking down cellulose and synthesizing protein from non-protein sources. The multi-chambered stomach, constant feeding, and extensive microbial digestion underscore the adaptations to a plant-based diet, which is lower in nutritional density and requires continuous processing to extract sufficient nutrients.
Humans: Bridging the Gap
Drawing these threads together, it becomes clear that early humans likely bridged the gap between these two dietary strategies. The efficiency and rapid digestion associated with carnivorous diets may have provided the nutritional density necessary for brain expansion and the development of complex social behaviours. Meanwhile, the ability to process plant matter, albeit less efficiently than modern herbivores, offered flexibility in subsistence strategies, especially as ecosystems changed over time.
The integration of meat into human diets, highlighted by both Ben-Dor and Voegtlin, suggests an evolutionary trajectory that favoured high-energy, nutrient-dense foods. This preference for meat, alongside the capacity to exploit a wide range of other food sources, including plants, played a crucial role in human adaptation and survival across diverse environments.
Evolutionary Implications
The evidence from both archaeological findings and the study of digestive physiology indicates that meat consumption was not merely a dietary choice but a fundamental aspect of human evolution. The adaptations seen in the human digestive tract, comparable in some aspects to carnivores but also capable of processing plant-based foods, reflect the omnivorous nature that allowed early humans to thrive in varied ecological niches.
By understanding the dietary practices of our ancestors, we gain insight into the evolutionary pressures that shaped our physiology, social structures, and technological advancements. The exploration of our dietary past continues to inform current discussions on nutrition, health, and the environmental impacts of our food choices, underscoring the deep connections between diet, evolution, and the human experience. Bile, produced by the liver and stored in the gallbladder, is released into the small intestine to aid in the digestion and absorption of fats. This process is crucial for the effective digestion of dietary fats, allowing them to be emulsified and subsequently absorbed by the intestinal lining.
Voegtlin’s perspective, articulated in 1975, posits a carnivorous inclination within human physiology, emphasizing the structure and function of the human digestive system as being optimally suited for the digestion of animal proteins and fats, with a limited capacity for processing plant materials and carbohydrates. His analysis draws attention to the human digestive tract’s similarity to that of carnivorous animals, suggesting that humans are designed for intermittent feeding on a diet primarily composed of animal protein and fat, with minimal inclusion of carbohydrates.
The human digestive system, as described, is relatively short and simple compared to herbivorous counterparts, which possess complex systems designed for the fermentation and breakdown of cellulose-rich plant material. Humans lack the extensive gut flora found in herbivores, which is essential for breaking down cellulose through fermentation. Instead, humans rely on a set of digestive enzymes produced by the pancreas and small intestine for the digestion of proteins, fats, and simple carbohydrates.
Voegtlin’s assertion about the appendix, suggesting its evolution from a functional cecum in response to dietary changes, underscores a broader debate regarding human dietary evolution. Whether the appendix is a vestigial organ from a herbivorous past or an evolving organ adapting to dietary shifts remains a subject of scientific inquiry. Nonetheless, its current function in the human body appears minimal, with little impact on digestion.
The emphasis on the human stomach’s ability to secrete strong acids capable of dissolving meat and fat highlights the carnivorous adaptation of the human digestive system. However, the capacity to digest and absorb nutrients from plant sources, albeit less efficiently than animal sources, suggests a level of omnivorous flexibility in human digestion. This adaptability may reflect evolutionary dietary shifts and the inclusion of a wider range of food sources in the human diet.
Voegtlin’s argument for a carnivore-aligned dietary pattern for humans, based on the structure and function of the digestive system, contributes to ongoing debates about optimal human nutrition. Modern nutritional science recognizes the complexity of human dietary needs, incorporating a broader understanding of nutrient requirements, metabolic health, and the role of dietary diversity in human evolution. While Voegtlin’s perspective provides insight into the physiological capabilities of the human digestive system, contemporary dietary recommendations emphasize balance, variety, and the inclusion of both animal and plant sources to meet nutritional needs effectively.
Conclusion
In conclusion, the human digestive system’s capability to process a diverse array of nutrients demonstrates an evolutionary trajectory marked by dietary flexibility. Voegtlin’s examination underscores the physiological alignment of humans with the consumption of animal proteins and fats, emphasizing the significance of understanding the subtleties embedded in human dietary evolution. An omnivorous diet plays a crucial role in fostering human health and nutrition, reflecting our adaptability. Simultaneously, a thorough assessment of biological, archaeological, paleontological, zoological, and ethnographic evidence reveals the intricacies involved in pinpointing the Pleistocene human trophic level. This evidence indicates a progression towards increased carnivory, notably through the specialization in hunting large game. Nonetheless, such conclusions, suggesting a high trophic level for Pleistocene humans, are based on indirect evidence and warrant further scrutiny. The pursuit of insights into human dietary history via a multidisciplinary lens illuminates the dynamic exchanges between humans and their environments across prehistory, illustrating the complex nature of our ancestral diets and their implications for our evolutionary development.
References
Bonhommeau et al (2013). Eating up the world’s food web and the human trophic level. PNAS, Vol 110 – 51.
Ben-Dor, M., Sirtoli, R., Barkai, R.. (2021) The evolution of the human trophic level during the Pleistocene, First published: 05 March 2021 https://doi.org/10.1002/ajpa.24247
Voegtlin, W. L.. (1975) The Stone Age Diet. Vantage Press.
Conny Waters (2022) Humans Were Apex Predators For Two Million Years, AncientPages.com