Stone Age Sustenance: How Meat and Animal Fat Shaped Paleolithic Diets

Human diets have evolved across a wide spectrum of regional, seasonal, and ecological contexts. Early hominins were opportunistic foragers, relying on both plant and animal resources. As they transitioned from forests to open savannahs, red meat, marrow, and organ meats became increasingly important. These foods provided essential energy and micronutrients that were crucial for brain expansion. It is likely that even older infants and toddlers became dependent on the supply of (premasticated) meat for adequate nourishment and development.

Foraging shaped social structures, cooperation, and tool use, leading to technological innovations that improved dietary breadth. As humans dispersed globally, they adapted to diverse ecosystems, developing unique dietary patterns. Already one million years ago, during the Middle Pleistocene Transition, Homo erectus populations expanded into various African and Eurasian steppe-desert regions and beyond. In arid or icy environments, where plant resources were limited, humans relied heavily on large herbivores, prioritizing fatty cuts of meat. In tropical regions, diets incorporated more fruits, tubers, seeds, and nuts, while coastal populations included seafood and marine fats.

Cooking, fermentation, and other forms of processing improved the safety, digestibility, and nutrient availability of both plant and animal foods, further diversifying diets even within similar environments. Seasonal variations also played a role, with leaner times necessitating a reliance on preserved foods. Despite these variations, ancestral diets typically included a mixture of plants and animal-sourced foods, with macronutrient ratios tailored to local resources. This dietary flexibility enabled humans to thrive in a wide range of environments as dietary generalists.

After transitioning into more open ecosystems, some three million years ago, hominins increasingly relied on aggressive scavenging. Grassland-derived nutrients, especially those from meat, fat, marrow, and organs, thus entered the ancestral diet. One million years ago, Homo erectus began to expand into the arid steppe-desert regions of Africa and Eurasia, acting as flexible ecological generalists. Both thermal and non-thermal processing helped to diversify dietary breadth. The controlled use of natural fire by hominins dates back 800,000 years ago or more, which eventually evolved into fire-making technology, at least 400,000 years ago. 

A turning point was reached when improved hunting skills enabled access to large herbivores. At least some of the upper-Paleolithic diets became dominated by red meat and fat, with mammoth protein comprising up to two-thirds of the intake of Neanderthals and early ‘modern humans’ in certain regions of Eurasia. Their ability to process and store large amounts of meat allowed them to manage seasonal shortages and enabled temporary group aggregations. However, the extinction of megafauna eventually pushed humans toward smaller, faster prey, driving advancements in agility and hunting techniques. 

During the late stages of the Pleistocene, humans adapted to ecological challenges by diversifying their diets to include more eggs, fish, seafood, and plants. The shift toward smaller game required greater precision, planning, and cooperation, advancing social complexity and innovation. Long-range weapons and improved food processing techniques also enhanced food security. 

Animal-sourced foods were essential in all pre-agricultural diets. On average, modern foragers still derive more than half of their energy from hunting and fishing. In cold environments this even reaches higher shares (>90%), while the caloric budget is dominated by plants for only a minority of groups. Meat and animal fat consumption ranges from 5% to 90% of total caloric intake, with annual intake levels of 40-650 kg per person, depending on the group and region.

In the Paleolithic, 30-70% of caloric intake similarly came from animals, possibly higher in areas with mega-herbivores and during glacial conditions. Homo habilis likely consumed only around 10%, being still close to the Australopithecus lineage. For the obligate bipedal and larger-brained Homo erectus, arguably the first true representative species of Homo, the contribution may have been 60% or more, and for Homo neanderthalensis even up to 80%. Nonetheless, landscapes and food sources may have been more diverse and with a higher access to plants than often assumed, even in extreme cold conditions.

Early ‘modern humans' were nonethless mostly heavily carnivorous in the presence of megafauna. As an example, the Clovis culture may have obtained up to 95% of calories from large herbivores, such as mammoths. After the megafauna extinction, especially during the Mesolithic ‘Broad Spectrum Revolution’, diets became more diversified while more sophisticated processing enhanced the role of foods like tubers and grains. Macronutrient ratios differed based on ecological factors, with some diets being low in carbs and high in protein, while others incorporated more starches.