Sugar May Have Powered the Evolution of the Human Brain, Study Finds

Fruit, honey, and other naturally sweet foods may have played an important role in the evolution of the human brain, new research suggests. The study comes from scientists at the University of Sydney and the University of Glasgow. It was published in the journal Science.

The team built a model. It tracked the sugar needs of humans and their ancestors across four million years. Their conclusion was clear. Natural sugars gave early humans a huge energy boost. This happened long before cooking made starchy foods like grains and root vegetables simple to eat.

Jennie Brand-Miller led the study. She is a professor of human nutrition at the University of Sydney. She explained that raw starch is challenging for the body to use. It does not break down into sugar easily without cooking. So early humans probably depended on naturally sweet foods first. Grains came much later.

This idea challenges an older theory. For years, many scientists believed meat was the main driver of human brain evolution. This new study offers a different angle. It also may explain why humans still crave sweet things today.

Brand-Miller pointed out something important. Meat mattered, yes. But scientists have often overlooked how much the brain relies on sugar. That gap in research is what this study tries to fill.

A Growing Brain Needs More Fuel

Over four million years, the human brain changed a lot. It grew from about 300 grams in early ancestors to roughly 1,500 grams in people today. As the brain got bigger, its need for sugar grew too. This sugar, called glucose, doesn’t just fuel the brain. It also powers red blood cells, the kidneys, and reproductive organs.

Brand-Miller noted that the human brain is unusually large for our body size. It burns a lot of energy just to function. Glucose is its main fuel source. For most of human history, that glucose came from carbohydrates in fruit and honey.

Building the Model

To test their idea, researchers created a timeline. It covered six major stages of human evolution. At each stage, they looked at how much animal and plant food our ancestors likely ate. They wanted to see if carbs could have supplied enough glucose to support brain growth.

They pulled together evidence from many fields. This included studies on food, metabolism, ancient bones, teeth, archaeology, primate diets, and genetics.

Their results point to something intriguing. Early hominins, like the famous “Lucy,” had brains close in size to a chimpanzee’s. Homo habilis and Homo erectus likely leaned heavily on fruit for energy. Later, once fire and cooking became common, humans could finally obtain glucose from starchy underground plants. Think wild yams and water lily roots.

Brand-Miller added that flour and grains show up in the archaeological record much later. Most people assume carbs mean bread and cereal. But for most of human history, carbs mostly meant fruit, honey, and roots.

Sugar and Reproduction

The study also looked at pregnancy. Researchers found that pregnant and breastfeeding women needed far more glucose than other adults. This is because a growing fetus, the placenta, and milk production all demand extra sugar.

David Raubenheimer co-authored the study. He said brain growth isn’t the only factor to consider. The needs of pregnancy and child-rearing matter too. This phenomenon may explain why pregnant women often crave fruit.

The same idea might explain why children love sweet foods. According to Brand-Miller, this craving is instinctive. Kids’ brains use up to two-thirds of their energy during early development. That means they need extra carbs to keep up.

Rethinking How We See Sugar

Brand-Miller argued that natural sugar deserves more respect. Fruit and honey aren’t just treats. For most of human history, they were essential fuel. She also noted that natural sugar rarely comes alone. It’s usually packaged with fiber, vitamins, and minerals.

Honey, she said, isn’t empty calories. It was once a prized food, valued for both energy and health benefits. The researchers’ takeaway is simple. Carbs helped fuel human brain growth. Instead of avoiding carbs altogether, people should choose beneficial ones. Fruit, legumes, and whole grains are smart picks for a balanced diet. Sugar May Have Powered the Evolution of the Human Brain, Study Finds

Fruit, honey, and other naturally sweet foods may have played an important role in the evolution of the human brain, new research suggests. The study comes from scientists at the University of Sydney and the University of Glasgow. It was published in the journal Science.

The team built a model. It tracked the sugar needs of humans and their ancestors across four million years. Their conclusion was clear. Natural sugars gave early humans a huge energy boost. This happened long before cooking made starchy foods like grains and root vegetables simple to eat.

Jennie Brand-Miller led the study. She is a professor of human nutrition at the University of Sydney. She explained that raw starch is challenging for the body to use. It does not break down into sugar easily without cooking. So early humans probably depended on naturally sweet foods first. Grains came much later.

This idea challenges an older theory. For years, many scientists believed meat was the main driver of human brain evolution. This new study offers a different angle. It also may explain why humans still crave sweet things today.

Brand-Miller pointed out something important. Meat mattered, yes. But scientists have often overlooked how much the brain relies on sugar. That gap in research is what this study tries to fill.

A Growing Brain Needs More Fuel

Over four million years, the human brain changed a lot. It grew from about 300 grams in early ancestors to roughly 1,500 grams in people today. As the brain got bigger, its need for sugar grew too. This sugar, called glucose, doesn’t just fuel the brain. It also powers red blood cells, the kidneys, and reproductive organs.

Brand-Miller noted that the human brain is unusually large for our body size. It burns a lot of energy just to function. Glucose is its main fuel source. For most of human history, that glucose came from carbohydrates in fruit and honey.

Building the Model

To test their idea, researchers created a timeline. It covered six major stages of human evolution. At each stage, they looked at how much animal and plant food our ancestors likely ate. They wanted to see if carbs could have supplied enough glucose to support brain growth.

They pulled together evidence from many fields. This included studies on food, metabolism, ancient bones, teeth, archaeology, primate diets, and genetics.

Their results point to something intriguing. Early hominins, like the famous “Lucy,” had brains close in size to a chimpanzee’s. Homo habilis and Homo erectus likely leaned heavily on fruit for energy. Later, once fire and cooking became common, humans could finally obtain glucose from starchy underground plants. Think wild yams and water lily roots.

Brand-Miller added that flour and grains show up in the archaeological record much later. Most people assume carbs mean bread and cereal. But for most of human history, carbs mostly meant fruit, honey, and roots.

Sugar and Reproduction

The study also looked at pregnancy. Researchers found that pregnant and breastfeeding women needed far more glucose than other adults. This is because a growing fetus, the placenta, and milk production all demand extra sugar.

David Raubenheimer co-authored the study. He said brain growth isn’t the only factor to consider. The needs of pregnancy and child-rearing matter too. This phenomenon may explain why pregnant women often crave fruit.

The same idea might explain why children love sweet foods. According to Brand-Miller, this craving is instinctive. Kids’ brains use up to two-thirds of their energy during early development. That means they need extra carbs to keep up.

Rethinking How We See Sugar

Brand-Miller argued that natural sugar deserves more respect. Fruit and honey aren’t just treats. For most of human history, they were essential fuel. She also noted that natural sugar rarely comes alone. It’s usually packaged with fiber, vitamins, and minerals.

Honey, she said, isn’t empty calories. It was once a prized food, valued for both energy and health benefits. The researchers’ takeaway is simple. Carbs helped fuel human brain growth. Instead of avoiding carbs altogether, people should choose beneficial ones. Fruit, legumes, and whole grains are smart picks for a balanced diet.