Paleolithic diets: meat, animal fat, and hunter-gatherers

Human diets do not adhere to a single, universal model but have instead evolved across a wide spectrum of regional, seasonal, and ecological contexts. Early hominins were opportunistic foragers, relying on available plant and animal resources. As humans transitioned from forested areas to open savannahs, animal-sourced foods, such as meat, marrow, and organs, became increasingly important. These foods provided essential energy and micronutrients that were crucial for brain expansion.

Foraging shaped human 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. In ice-age 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, and nuts, supplemented by small game.  Coastal populations included seafood and marine fats, while inland groups hunted animals and gathered seasonal plants.

Cooking and fermentation enhanced the 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 greater reliance on stored or preserved foods. Despite these variations, ancestral diets typically included a mixture of animal-sourced and plant-based foods, with macronutrient ratios tailored to local resources. This dietary flexibility enabled humans to thrive in a wide range of environments as dietary generalists.

Between 2–3 million years ago, hominins began transitioning from forested areas to savannahs, relying increasingly on animal-sourced foods like meat, marrow, and organs through scavenging and hunting. Animal-derived nutrients, including those from meat, fat, marrow, and organs, played a key role in human evolution, shaping anatomy and metabolism. This dietary shift marked a turning point, with improved hunting skills enabling access to large herbivores. 

During 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’. 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 pushed humans toward smaller, faster prey, driving advancements in agility, cognitive skills, and hunting techniques. 

During the last stages of the Pleistocene, humans adapted to ecological challenges by diversifying their diet to include smaller animals, eggs, fish, and plant-based foods. This shift toward smaller game required greater precision, planning, and cooperation, advancing human innovation and social complexity. Long-range weapons and improved food processing techniques also enhanced food security. These adaptations underscore the evolutionary significance of animal-sourced foods, not only as primary nutrient sources but also as drivers of physical and cognitive development. By targeting diverse prey and improving tools and techniques, humans evolved into apex predators capable of thriving in various ecosystems.

Animal-sourced foods were essential in pre-agricultural diets, although estimates are uncertain. Modern hunter-gatherers, often used as models, derive about 50-65% of their energy from hunting and fishing on average. In cold environments this can even reach higher shares (>90% kcal), while the caloric budget is dominated by plants for only a minority of foraging groups. 

Meat consumption specifically ranges from 5% to 90% of total caloric intake in such modern hunter-gatherer communities, with annual consumption usually varying between 40 and 650 kg per person, depending on the group. In sub-Arctic regions, Inuit diets can even include up to 300-500 kg of meat and 150-300 kg of blubber annually. 

In the Paleolithic, it is estimated that 30-70% of caloric intake similarly came from animal sources, possibly higher in areas with mega-herbivores and during glacial conditions. The proportion of animal-based calories also varied by species. 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 around 60% or more, and for Homo neanderthalensis even up to 80%. Although plants contributed to early human diets, they mostly supplemented animal foods. 

Early ‘modern humans’ (Homo sapiens) were heavily carnivorous in the presence of megafauna. The diet of the Clovis culture, for example, was almost entirely animal-based, with an estimated 95% of calories coming from large herbivores, particularly mammoths. After the megafauna extinction, diets became more diversified. The increasing sophistication of food processing and cooking techniques improved the digestibility of plants, making foods like tubers and grains more significant sources of energy and nutrients. Macronutrient ratios differed based on ecological factors, with some diets being low in carbs and high in protein, while others incorporated more starches and sugars like honey.