Carbohydrates and Sugars: Key Players in Human Evolution

A recent study sheds light on the critical role that carbohydrates and sugars played in the evolution of early humans. Evolutionary biologists suggest that our ability to perceive colors was primarily developed to help identify ripe, nutrient-rich fruits, which are often the sweetest. According to Professor Brand-Miller, the fruits that exhibit the most vibrant colors—deep reds, oranges, and yellows—are typically those with the highest sugar content. This ability to locate and consume these fruits may have provided a significant survival advantage for early humans, as different fruits ripen at various times throughout the year in tropical forests. The capacity to mentally map these resources would have favored those primates, including our ancestors, who could efficiently find ripe fruit trees before their competitors. This search for sugar-rich food likely stimulated cognitive development, leading to larger brains and enhanced memory capabilities.

Fossil evidence also indicates that early primates, including humans, had a diet rich in natural sugars, as shown by the prevalence of cavities in ancient remains. Brand-Miller notes that the increase in cavities among humans became particularly pronounced after the advent of cooking, which introduced starchy tubers and other carbohydrate-heavy foods that were previously indigestible.

Most of human evolution occurred in Africa, where ripe fruits and honey were plentiful. However, as humans migrated to colder and drier regions, the availability of dietary sugars diminished. This environmental shift likely continued to influence human evolution, leading to genetic adaptations that improved our ability to process sugars and carbohydrates. A prime example of this adaptation is the ability to digest lactose, the sugar found in milk. Unlike most animals, some humans can consume milk into adulthood, providing a crucial nutritional resource in climates where fresh fruit is scarce.

The Agricultural Revolution, which began around 10,000 years ago, marked another significant shift in human diets, as grains and starches like rice, corn, and potatoes became staples. This transition further increased carbohydrate consumption. Notably, humans possess multiple copies of the salivary amylase gene, which aids in the digestion of starchy foods, whereas chimpanzees have only one. This genetic variation highlights the evolutionary pressure to efficiently break down complex carbohydrates into glucose, which serves as a vital energy source for the brain. Brand-Miller emphasizes that these genetic changes underscore the importance of carbohydrate calories throughout human history.