Forensic anthropologists estimate sex from a skeleton — one of the "big three" identifiers alongside age and ancestry — using ordinal scoring of skeletal robusticity. Walker (2008) formalised five cranial traits, each scored on a 1 (most female-typical / gracile) to 5 (most male-typical / robust) scale by comparison to a reference chart: glabella, supraorbital margin, mastoid process, nuchal crest, and mental eminence. This simulator drives four of them from sliders (glabella and supraorbital margin are combined into one brow-ridge control) and morphs a 3D skull mesh to match.
Composite score S = sum of trait scores (range 4-20 here)
Trait average A = S / (number of traits)
Logistic sex estimate:
P(male) = 1 / (1 + e^(-k(A - 3))) with k ≈ 1.6
P(female) = 1 - P(male)
A is centred on 3 (the scale midpoint) so a perfectly average skull scores 50/50; each point above or below 3 shifts the odds toward male or female respectively, mirroring how a real discriminant-function sectioning point works — no single trait is decisive, but the sum is a reasonably reliable classifier (published accuracy for the full 5-trait method is roughly 85-90% when scored by a trained observer, which is why real casework backs it up with pelvic and long-bone measurements too).
- Glabella / brow ridge — the smooth-to-shelf-like ridge above the nose; male skulls typically show a projecting bony shelf.
- Mastoid process — the bony bump behind each ear where neck muscles attach; larger and more angular in males.
- Nuchal crest — the muscle-attachment ridge on the back of the skull for neck extensors; a rugged crest with a hook is a strongly male-typical trait.
- Mental eminence — the chin; a broad, square, bulging chin is more male-typical than a narrow, rounded, receding one.
Drag on the canvas to orbit the skull and inspect each landmark from any angle.