Tracing Our Roots: What was the first thing eaten by humans? A Journey Into the Prehistoric Nutrition Diet

October 1, 2025 •

3 min read

The diet of our earliest hominid ancestors was primarily plant-based, consisting of fruits, leaves, and nuts, which suggests the answer to what was the first thing eaten by humans? is far more complex than a single food item. The evolution of the human diet was a journey of gradual adaptation, influenced by environment, tool use, and climate.

Quick Summary

The earliest human ancestors primarily consumed plants like fruits, leaves, and nuts, supplemented opportunistically with insects and small animals, transitioning toward a broader omnivorous diet with increased meat consumption around 2.6 million years ago, fueled by developing tool technology and environmental shifts. Subsequent innovations like cooking further diversified food options and improved nutrient absorption.

Key Points

Pre-human ancestors were vegetarian: The earliest hominids, like Australopithecus, primarily consumed fruits, leaves, nuts, and possibly insects, similar to modern chimpanzees.
Meat consumption coincided with tools: The introduction of meat and marrow into the diet around 2.6 million years ago, enabled by the first stone tools for butchery, was a critical evolutionary step for the genus Homo.
Dietary evolution wasn't uniform: Prehistoric diets varied significantly based on geographic location and available resources, debunking the myth of a single, universal “caveman” diet.
Cooking revolutionized nutrient absorption: The discovery and use of fire, likely by Homo erectus, allowed for the cooking of foods, increasing nutrient availability and caloric intake.
Dietary flexibility drove success: The ability to adapt to new environments and exploit a wide range of food sources, from scavenged meat to cooked tubers, was crucial for human survival and evolutionary success.
Scientific evidence is multifaceted: Anthropologists use dental analysis (microwear, calculus), isotopic studies, and archaeological remains to piece together the complex story of our ancestors' eating habits.

The Earliest Foragers: A Plant-Based Foundation

To understand what our ancestors first ate, we must look at the earliest hominids, such as the Australopithecus species, which lived several million years ago. Their diet, much like that of modern great apes, was predominantly vegetarian, consisting of readily available plant matter.

Life Before Tools

Early hominids like "Lucy" (Australopithecus afarensis) possessed teeth and jaws adapted for grinding tough plant fibers and chewing fruits and leaves. This suggests a heavy reliance on soft plant foods, with harder plants like nuts and tubers possibly serving as fallback options during times of scarcity.

Fruits and Leaves: Soft fruits and tender leaves were likely a dietary staple, providing essential energy and nutrients.
Nuts and Seeds: These provided calorie-dense energy but were likely tougher to process without advanced tools.
Insects: Opportunistic consumption of insects, like termites, would have offered a valuable source of protein.

The Crucial Shift to Animal Protein

A significant turning point in the human dietary story came approximately 2.6 million years ago, with the emergence of the Homo lineage, particularly Homo habilis. This shift was characterized by a dramatic increase in the consumption of meat and marrow, likely from scavenging carcasses left by large predators.

The Rise of Tool Technology

The development of the first stone tools coincided with this dietary change. These tools, found alongside butchered animal bones, provided the means to:

Slice meat from carcasses more efficiently than with bare hands.
Crack open bones to access the highly nutritious, energy-dense marrow inside.

This shift to a higher-quality, more calorie-dense diet had profound evolutionary consequences, including a reduction in gut size and the fueling of a larger, more energy-demanding brain.

Evidence for Ancient Diets

Determining the dietary habits of our ancient ancestors is not straightforward and relies on a blend of different scientific methods.

How We Reconstruct Prehistoric Diets

Dental Microwear: Analyzing the microscopic scratches and pits on fossilized teeth reveals what foods were chewed. Hard foods leave different marks than soft, leafy ones.
Dental Calculus Analysis: Mineralized plaque (calculus) on ancient teeth can trap microfossils of plants, providing direct evidence of what was eaten.
Isotopic Analysis: By studying the ratio of different carbon and nitrogen isotopes in fossilized bones and teeth, scientists can determine the types of plants and the amount of meat an individual consumed.
Archaeological Evidence: The presence of butchered animal bones alongside stone tools is a clear sign of meat consumption.

The Impact of Cooking

The controlled use of fire, perfected by Homo erectus around 1.8 million years ago, marked another revolution in human nutrition. Cooking made tough meat safer and easier to digest, while also unlocking more carbohydrates and calories from plant foods like tubers. This innovation allowed for further brain growth and dietary diversification.

The True "Paleo" Diet Was Diverse

The popular conception of a "Paleo diet" as a single, meat-heavy regimen is a simplification. The reality is that hominid diets varied dramatically depending on geography, climate, and the available local resources. While some populations, particularly in colder climates, relied heavily on animal products, others in more resource-rich areas consumed far more plants.

A Comparison of Early Hominin Diets


Feature	Australopithecus Diet (~4-2.5 mya)	Early Homo Diet (~2.5-1.5 mya)
Dominant Food Source	Plants (fruits, leaves, roots)	Omnivorous (significant increase in meat and marrow)
Primary Hunting Strategy	Opportunistic (insects, small prey)	Scavenging large animals, small-game hunting
Tool Use	Limited (similar to modern primates)	First stone tools for butchering
Key Dietary Innovation	Behavioral adaptation to new plant sources	Tool-assisted scavenging for high-energy nutrients
Nutrient Density	Lower-density, fibrous plant foods	Higher-density meat and marrow

Conclusion: An Omnivorous Evolution

In summary, the first food eaten by humans was not a singular meal but a wide variety of plant-based foods, such as fruits, leaves, and nuts, reflecting our omnivorous primate ancestry. The subsequent shift to regularly incorporating animal protein, enabled by tool use, provided the energy required for the remarkable brain expansion that defines the genus Homo. As our ancestors evolved and dispersed, their diets continued to adapt, incorporating cooked starches and an even broader range of flora and fauna, demonstrating that dietary flexibility has been a key to human survival and success.

To learn more about the complex journey of human dietary evolution, explore the resources from the Australian Museum on prehistoric diets.

Frequently Asked Questions

Evidence suggests that early members of the genus Homo, around 2.6 million years ago, primarily obtained meat through scavenging carcasses left by large predators before developing more advanced hunting techniques.

Scientists use several methods, including analyzing fossilized teeth for wear patterns, studying microfossils in dental plaque (calculus), and measuring carbon and nitrogen isotopes in ancient bones to determine dietary habits.

The controlled use of fire and cooking is believed to have begun much later in human history, possibly with Homo erectus around 1.8 million years ago, which significantly improved digestion and energy extraction.

No, studies on tooth enamel indicate that Australopithecus, including the famous "Lucy" fossil, consumed a diet consisting mainly or exclusively of plants and did not regularly eat large amounts of meat.

The shift towards consuming more nutrient-dense and high-calorie foods, particularly meat and cooked starches, is widely believed to have provided the extra energy needed to fuel the expansion of the human brain.

No, the modern "Paleo Diet" is a simplified representation based on popular assumptions. The actual diet of prehistoric humans was far more diverse and varied significantly by region and era, often including cooked tubers, seeds, and wild grains.

Recent studies examining Neanderthal and early modern human dental calculus have found evidence of cooked plant foods, showing a culinary complexity not previously understood. Cooking damages starches in a way that is visible under a microscope.