Library.

“The majority of a human's brain is almost always active.”

The claim captures the broad scientific picture that the human brain is active across most states, including rest and sleep, rather than lying mostly dormant. However, it overstates precision: activity is uneven across regions, and deep non-REM sleep significantly lowers overall brain metabolism. The statement is best understood as a rebuttal to the "10% of the brain" myth, not as a strict quantitative rule.

“In adults under typical conditions, the human brain accounts for about 2% of total body weight but consumes about 20% to 25% of the body's glucose or energy.”

The core claim matches standard physiology references: an adult human brain is about 2% of body weight and uses roughly 20% of the body’s energy, with some sources placing glucose use near 20–25% at rest. The caveat is that these figures are usually stated for resting metabolism, and “glucose” and “energy” are related but not identical measures.

“More than 3,000 human genes show sex-specific expression patterns in the human brain.”

Recent high-quality research directly supports the 3,000+ figure: a 2025 single-cell study of the human cerebral cortex reports "over 3,000 unique genes" with sex-biased expression, and independent transcriptomic analyses corroborate counts in this range. However, the claim's unqualified framing omits important context — the number varies substantially by developmental stage (dropping to roughly 1,000 in the adult forebrain), brain region, and methodology, and cross-study consensus on which specific genes are sex-biased remains limited.

“The human brain uses 20% of the body's total oxygen supply.”

The claim is well-supported by multiple peer-reviewed biomedical studies confirming that the adult human brain consumes approximately 20% of the body's total oxygen at rest. This is a widely accepted figure in neuroscience. Minor caveats: the figure applies specifically to adults in a resting/basal state, some sources cite a 15–20% range, and the proportion is significantly higher in young children. These are standard qualifications that don't undermine the claim's core accuracy.