Why Did People Eat Starch? An Evolutionary Perspective

November 30, 2025 •

3 min read

Over the past million years, human brain size accelerated, a phenomenon once attributed solely to meat consumption. However, recent research compellingly demonstrates why people ate starch, revealing that starchy plant foods were a critical energy source that fueled the evolution of our large, glucose-hungry brains. This shift, combined with the advent of cooking, fundamentally changed our evolutionary trajectory.

Quick Summary

Starches were essential for human evolution, providing glucose to fuel brain development and reproduction. Cooking made starches more digestible, enhancing their energy-yielding potential. Archaeological and genetic evidence confirms that starchy plants were a key part of early human diets, challenging the myth of a strictly carnivorous 'paleo' past.

Key Points

Brain Development: Starch provided the essential glucose that fueled the massive energy demands of the evolving human brain, especially after cooking became widespread.
Consistent Energy: Unlike unpredictable meat supplies, starchy tubers and roots offered a reliable, year-round source of calories for early hunter-gatherers.
Cooking's Importance: The advent of cooking made starches far more digestible, unlocking their high energy potential and making them a viable food source.
Genetic Adaptation: The duplication of salivary amylase genes in humans, which aids starch digestion, co-evolved alongside the cultural practice of cooking.
Dietary Versatility: Evidence suggests that early humans and Neanderthals were omnivores who strategically balanced meat and gathered starchy plants for optimal nutrition.
Refuting Modern Myths: The historical record of starch consumption challenges the modern 'paleo' diet philosophy that largely excludes this critical food group.

The Surprising Truth About the Paleolithic Diet

While popular culture often emphasizes a meat-focused 'Paleo' diet, mounting archaeological and genetic evidence indicates that early humans and Neanderthals regularly consumed starches from sources like tubers, roots, and seeds. This wasn't a minor part of their diet; starches provided a crucial and consistent energy supply that hunting alone couldn't guarantee. The availability and nutritional value of these starchy plants helped early hominins adapt to various environments and support the energy needs of their developing brains.

The Role of Cooking and Digestion

The ability to control fire and cook food marked a significant evolutionary turning point. Cooking dramatically changes the structure of starches, making their carbohydrates much more digestible and readily available as glucose.

Enhanced Energy: Cooking gelatinizes starch, making it easier for our bodies to access and convert into glucose, the brain's primary fuel.
Increased Edibility: This process also helped neutralize potential toxins in some raw plant foods, expanding the range of edible starches.
Genetic Adaptation: As cooking and starch consumption became more prevalent, humans developed more copies of the salivary amylase gene compared to other primates. This enzyme is specifically designed to break down starch, and its increased presence in humans is thought to have evolved alongside our dietary changes.

Starch as a Brain Fuel

The human brain is exceptionally energy-demanding, consuming up to 25% of our basal metabolism. This high glucose requirement could not be consistently met by a low-carbohydrate, meat-heavy diet alone. Starch provided a stable and ample source of glucose, essential for supporting a larger brain. This was particularly important during growth phases like pregnancy and infancy when glucose needs are highest.

Why Starch Was Superior to Meat in Some Cases

Meat offered valuable protein and fats but was an unpredictable food source. In contrast, starchy plants could be reliably gathered and stored, providing a consistent food supply. This reliability was a major evolutionary advantage, particularly during periods of migration or when hunting was unsuccessful. Studies of contemporary hunter-gatherer groups often show that gathered plant foods contribute significantly to their caloric intake.

Starch vs. Low-Carb Diet: The Modern Interpretation


Feature	Ancestral Starch Consumption	Modern Low-Carb Diet
Energy Source	Primary and consistent source of glucose.	Restricts glucose, relies on fats and gluconeogenesis.
Digestion	Relied on cooking for high digestibility.	Often avoids complex carbs, can be taxing on digestive effort.
Reliability	Provided a reliable food source even during unsuccessful hunts.	Potentially less reliable for sustained energy during high activity levels.
Brain Fuel	Essential for rapid brain growth and sustained function.	Debated whether it adequately fuels the high demands of the modern human brain.
Evolutionary Fit	Co-evolved with salivary amylase genes and cooking.	A recent dietary trend that does not align with deep evolutionary history.

Conclusion: More Than a Meal

Understanding "why did people eat starch?" reveals its crucial role in human evolution. Starch consumption, made possible by cooking, was fundamental to human development. It provided the consistent energy required for significant brain growth and maintenance, enabled survival in diverse environments, and drove genetic adaptations. Far from a minor food source, starch was a cornerstone of the ancestral diet, highlighting the deep connection between human intelligence and the starchy plants our ancestors utilized.

For more detailed insights into the archaeological findings of ancient diets, research compiled by the National Institutes of Health offers valuable resources.

The Lasting Legacy of Starch

Our efficient processing of starches is a result of evolutionary pressures. Accessing this dense, dependable energy source was a survival advantage that shaped our biology. Starchy foods remain vital carbohydrate sources globally today. Exploring our evolutionary link to starch illuminates its long-standing significance in human health and history.

Frequently Asked Questions

No, extensive archaeological and genetic evidence indicates that early humans were omnivores who consumed a wide variety of plant foods, including starchy roots and seeds, alongside meat.

Cooking was a game-changer. It gelatinized the starch molecules, making the carbohydrates much easier for the body to digest and absorb, thereby greatly increasing the energy gained from starchy foods.

Starch consumption provided the consistent glucose supply needed to fuel the high metabolic demands of the growing human brain. This reliable energy source played a critical role in the rapid increase of brain size over the last million years.

Genetic studies show that humans have more copies of the gene that produces salivary amylase. This genetic adaptation likely co-evolved with our ancestors' increased consumption of starchy foods and the adoption of cooking.

Research suggests the popular perception of a meat-centric 'paleo' diet is misleading. Our ancestors, including Neanderthals, ate significant amounts of starchy plants, indicating a more varied, omnivorous diet than the modern version suggests.

Archaeologists have found charred remains of starchy plants, such as tubers and roots, in ancient hearths and caves, including at sites dating back over 100,000 years in South Africa.

While meat provided fats and proteins, it was often an unreliable source of energy. Starchy plants were a predictable and abundant alternative that offered a dense source of carbohydrates, ensuring survival and sustained energy during periods of low hunting success.