Evidence atlas
Sex differences
A guide to established reproductive differences and measured average brain differences, with the scale, uncertainty, and limits of each finding kept visible.
In this article
Reading sex-difference evidence
Humans have two reproductive sexes, organized around large ova or small sperm. The two reproductive sexes differ in gametes, reproductive anatomy, endocrine organization, and reproductive functions. Variations in sex development can alter individual traits without creating another gamete class ( Endocrine Society scientific statement; review of anisogamy and the two reproductive sexes).
Average brain differences are reproducible, but their direction and magnitude vary by measure, region, task, sample, and statistical model. Structural size, cell count, activation, connectivity, and hormone-sensitive plasticity are different measurements. These results show why robust does not mean large, and overlap limits individual inference without erasing a measured group mean. An unedited early-access multi-task study reported internally split-half-stable, task-specific functional associations; because the publisher warns that this production-stage version may contain errors, its claims should be rechecked against the edited version when available.
Lateralisation shows the required calibration: a review found slightly stronger average male lateralisation across many measures, with small meta-analytic estimates; large-sample work found regional sex associations within distributed structural asymmetry patterns. A separate meta-analysis found no reliable male-female difference in language lateralisation. A reproducible finding can therefore be small, regional, or null.
This resource is educational and non-diagnostic. It cannot establish an individual person's physiology, desire, sexual orientation, behaviour, or consent.
Explore the anatomy
The atlas is an anatomical reference, not a male or female template. In each exhibit, evidence controls highlight measured locations or documented participants while the surrounding article explains what the comparison can support.
Atlas exhibits
Available evidence maps
- Sexual response and reproductive control How distributed brain systems contribute to sexual response and reproductive endocrine control.
- Brain structure, scaling, and variability How brain-size adjustment, regional morphometry, between-person variability, and hemispheric asymmetry shape measured female-male group differences in human brain structure.
- Pain sensitivity and modulation How average differences in experimental pain sensitivity relate to shared acute-pain maps, limited PAG-connectivity findings, peripheral nociceptor physiology, and uncertain endogenous modulation.