What our ancestors really ate: The evidence

Modern archaeology has moved beyond the simple cataloging of stone tools and pottery shards. Today, researchers increasingly focus on reconstructing the diets of our ancestors through internal evidence. Two primary methods dominate this field: the analysis of coprolites (fossilized feces) for direct, short-term snapshots of meals, and stable isotope analysis of skeletal remains for long-term dietary patterns. Together, these approaches reveal that human survival involved a complex mix of scavenging, gathering, hunting, selective food processing, and adaptation to diverse environments.

Insights from Paleofeces

Coprolites provide a high-resolution record of individual meals. Unlike bone chemistry, which averages diet over years, a coprolite captures undigested residues from a relatively short period. Analysts examine macroscopic remains (such as seeds, fish scales, and bone fragments) as well as microscopic evidence (including pollen, parasites, and starch granules). Chemical methods further identify plant cuticles and proteins.

A key methodological advance is the CoproID bioinformatics framework, published in 2020. It uses shotgun metagenomic DNA sequencing combined with machine learning to distinguish human paleofeces from canine ones (which can appear morphologically similar) and from non-fecal sediments. By integrating ancient host DNA with microbiome composition, CoproID enables more accurate reconstructions of the human microbiome and the specific plant and animal taxa consumed.

Advancements in Isotope Analysis

While coprolites offer detailed snapshots, stable isotope analysis of bone collagen provides a broader, lifetime-scale narrative. Measurements of carbon (δ¹³C) and nitrogen (δ¹⁵N) isotopes help differentiate between marine and terrestrial resources, or between plants using C₃ versus C₄ photosynthetic pathways, and indicate the relative contribution of animal protein.

Recent technological refinements include high-resolution mass spectrometry techniques, such as Electrospray-Orbitrap (ESI-Orbitrap), which allow multi-isotopologue analysis on small sample sizes. Compound-Specific Isotope Analysis of Amino Acids (CSIA-AA) further disentangles complex dietary and metabolic signals that bulk analysis may obscure. These tools are increasingly combined with machine learning to improve dietary reconstructions and trace population movements.

Stability and Change in the Archaeological Record

Recent studies highlight both remarkable stability and periods of dietary fluidity.

Research on the Moriš culture in the Middle Bronze Age of Serbia (approximately 2100-1550 BCE, within the broader cultural timeframe of ~2700-1500 BCE) analyzed stable carbon and nitrogen isotopes from human and animal bone collagen. Data from multiple cemeteries show a consistent reliance on livestock - primarily cattle, sheep, goats, and horses - supplemented by domestic C₃ plants. This dietary stability persisted for centuries, suggesting a resilient and sustainable agro-pastoral system that adapted to environmental and social changes without major shifts in core food sources.

In contrast, isotopic studies from prehistoric north-central Poland reveal more dynamic transitions. Early Corded Ware communities (around 2800 BCE) initially herded animals in forested areas or wet river valleys, producing isotopic signatures distinct from those of local sedentary farmers who used open grasslands. Over time, their diets became more similar to those of the established farming populations. By the Early Bronze Age, variations in nitrogen isotope values indicate that some individuals had greater access to animal protein, pointing to emerging social hierarchies and unequal resource distribution.

Survival Strategies and Environmental Mastery

Human evolutionary success often stemmed from dietary flexibility. Our ancestors are increasingly seen as a "broad-spectrum" species, capable of exploiting diverse resources to buffer against seasonal shortages and environmental variability.

Multi-proxy isotope analysis (including bulk collagen, enamel bioapatite, and CSIA-AA) at the Mesolithic cemetery of Yuzhniy Oleniy Ostrov (Lake Onega region, north-western Russia) examined remains from around 60 individuals. Despite its inland location, the data reveal an unusually high reliance on freshwater resources from the Lake Onega system, with lower contributions from terrestrial game than might be expected. This underscores the importance of aquatic resources in certain hunter-gatherer-fisher economies.

Scavenging and the Use of Fire

Scavenging of animal carcasses likely represented a significant, low-risk strategy for obtaining high-calorie marrow and meat. Biological adaptations such as high stomach acidity and endurance walking supported this opportunistic behavior. While scavenging complemented hunting throughout much of human evolution, its precise role continues to be refined through ecological modeling and archaeological evidence.

Mastery of fire dramatically expanded the human dietary niche. At Gesher Benot Ya'aqov in Israel (~780,000 years ago), evidence includes charcoal - primarily from driftwood gathered along the ancient lakeshore - associated with controlled hearth activity. Taphonomic and crystallographic analyses of fish remains (primarily two species of large cyprinids, Luciobarbus longiceps and Carasobarbus canis) show they were exposed to controlled low temperatures (below 500 °C), consistent with deliberate cooking, probably in a hearth or earth-oven setting. This represents some of the earliest reliable evidence of hominins using fire to improve nutrient bioavailability and detoxify foods.

The Dark Side of Survival

Dietary and taphonomic analyses also reveal harsher realities. A study of Neanderthal remains from the Troisième caverne of Goyet in Belgium (dated ~41,000-45,500 years ago) identified butchery marks on bones of at least six individuals - primarily adult or adolescent females and younger male individuals from non-local groups. The modifications (including marrow extraction) closely resemble those on animal prey bones. Current analyses suggest selective exocannibalism that may have been predatory or competitive in nature - possibly linked to territorial tensions between groups - rather than purely ritualistic or desperation-driven. Notably, isotopic evidence confirms these individuals originated from a different region, and this cannibalism occurred during a period when early modern humans had already begun occupying neighboring areas of Northern Europe.

The Plant-Based Foundation

Far from being exclusive carnivores, prehistoric humans intensively processed plant foods long before agriculture. Microscopic analysis of starch residues and plant fragments on tools, combined with coprolite data from sites worldwide (including the Ocampo Caves in Mexico and various African contexts), demonstrates grinding, heating, and detoxification of diverse flora. Pre-agricultural diets were often exceptionally high in fiber, sometimes exceeding 100 grams per day in analyzed samples. Gathering and plant processing thus formed a fundamental component of the human evolutionary diet.