Research Reveals Sugar's Role in Human Brain Evolution

WHO:

Sci.News - Researchers from the University of Sydney and the University of Glasgow conducted the study.

Sci.News - Professor Jennie Brand-Miller is the lead author of the study.

WHAT:

Sci.News - The study argues that dietary sugars, rather than animal foods, played a decisive role in the expansion of the human brain over the past 4 million years.

Sci.News - Hominin brain size grew nearly fivefold, from about 300 grams in early relatives like Australopithecus afarensis to roughly 1,500 grams in modern Homo sapiens.

Sci.News - The study suggests adult glucose needs ranged from about 150 to 250 grams a day, depending on sex and reproductive status, with young children requiring roughly 125 grams.

Sci.News - Early hominins likely derived more than 65% of their energy from sugars, primarily from fruit.

Sci.News - The earliest evidence of seed grinding is 65,000 years ago, indicating the first use of grinding stones to make flour.

WHERE:

Sci.News - The research was conducted by teams from the University of Sydney and the University of Glasgow.

WHEN:

Sci.News - The findings were published in the journal Science.

WHY:

Sci.News - The researchers argue that the seasonal rise and fall of fruit and honey availability may have shaped foraging behavior and contributed to extinctions among hominin groups less able to secure enough carbohydrates.

Sci.News - The study suggests that understanding the role of carbohydrates alongside meat, fat, and protein provides a more complete picture of the human evolutionary journey.

HOW:

Sci.News - The authors calculated glucose requirements for the brain, red blood cells, kidneys, and reproductive tissues at different stages of human evolution and compared this demand against the likely carbohydrate content of ancestral diets.

(UPDATED August 7, 2026 10:49 UTC)

Researchers from the University of Sydney and the University of Glasgow, led by Professor Jennie Brand-Miller, have published a study in the journal Science that argues dietary sugars played a crucial role in the expansion of the human brain over the past four million years. The study reveals that early hominins likely derived more than 65% of their energy from sugars, primarily from fruit, and highlights that brain size grew nearly fivefold from early relatives to modern humans. Additionally, the researchers calculated glucose requirements for various body functions and suggest that understanding the role of carbohydrates alongside other nutrients offers a more complete picture of human evolution.