The Sweet Side of Human Evolution: Did Sugar Help Build the Human Brain?

For a long time, people have focused on meat when talking about human evolution. The common idea is that our ancestors ate more animal foods, which gave them lots of energy and nutrients, helping their brains grow bigger and more demanding than those of other primates.

A new study in Science offers a different and surprisingly sweet perspective. Researchers Jennie Brand-Miller, Karen Hardy, David Raubenheimer, and Les Copeland suggest that sugars from fruits and honey, and later starch from cooked plants, may have been key in helping the human brain evolve.

The brain’s carbohydrate problem

The human brain uses a lot of energy. Even though it is only about 2% of an adult’s body weight, it takes up a large share of the body’s resting energy, mainly using glucose as fuel. Over millions of years, as our ancestors’ brains grew from about 300 grams in Australopithecus afarensis to around 1,500 grams in modern humans, the need for easy-to-access glucose would have gone up a lot.

The researchers, therefore, asked a simple question: where did all that glucose come from?

Their analysis suggests that early hominins may have gotten much of their glucose from naturally sweet foods. Fruit and honey could give them easy access to sugars before they learned to digest cooked starch well. The study’s models show that sugars may have made up a big part of their diet.

From fruit and honey to cooked starch

The story did not end with fruit.

The researchers suggest that humans shifted from eating sweet foods to eating cooked starchy foods. Once people learned to control fire and process food, cooking made starchy plants much easier to digest and turned them into a key source of glucose.

From this perspective, new ways of preparing food, like pounding, processing, and cooking, were not just about making meals softer or tastier. These changes may have given our ancestors access to much more carbohydrate energy.

This gives us a more detailed view of how the human diet evolved. Animal foods were clearly important, but carbohydrates may have been just as important for meeting the high energy needs of a growing brain.

A different way to think about the human diet

The study does not claim that our ancestors ate sugar the way we do today. There is a big difference between eating whole fruits or natural honey and eating the highly processed, refined sugars common now.

Instead, the research points to something bigger. Human evolution may have depended on our ability to find, process, and get energy from many different foods.

Seasonal fruit, honey, underground plant foods, and later cooked starches could have been important sources of glucose. The researchers think that changes in how available these foods were may have shaped how our ancestors searched for food and even affected human evolution.

What does this mean today?

The findings should not be interpreted as a license to eat more refined sugar. Instead, they challenge the simple idea that carbohydrates were less important than meat in human evolution. Our ancestors survived and evolved by exploiting different nutritional opportunities—and by developing technologies that made previously difficult foods more useful.

So perhaps the history of the human brain was not written by meat alone. ISo maybe the story of the human brain is not just about meat. It could also be about fruit, honey, roots, grains, and our unique ability to turn plants into energy. sweeter than we once imagined.

Read more about it at https://www.science.org/doi/epdf/10.1126/science.aed8437