Sexual Dimorphism in Faces.

What sexual dimorphism is

Sexual dimorphism is the term for the physical differences between male and female members of the same species. In humans the most visible facial dimorphisms develop during puberty under different hormone signals:

• Testosterone drives wider jaws, larger gonial angles, longer midfaces, prominent brow ridges, longer philtrums, narrower eyes, and thinner lips
• Estrogen preserves the juvenile facial template — smaller jaw, shorter philtrum, fuller lips, larger relative eye size, smoother brow ridge — see neoteny

Before puberty, male and female faces are nearly indistinguishable. After puberty, the gap is huge — and the size of that gap (how dimorphic a face is) carries strong signal value in attractiveness scoring.

The dimorphic features list

Most face-rating systems track these as dimorphism inputs:

Feature	Male-typical	Female-typical
Jaw width	Wide	Narrow
Gonial angle	Sharp (110–120°)	Soft (125–135°)
Brow ridge	Prominent, low	Smooth, higher
Eye shape	Narrow, deep-set	Round, large relative
Lips	Thinner	Fuller
Philtrum length	Longer	Shorter
Midface length	Longer	Shorter
fWHR	Higher	Lower
Chin	Projected, square	Recessed, pointed
Skin texture	Coarser, more body hair	Smoother

A face that hits the male column on every row is “highly masculine.” A face that hits the female column on every row is “highly feminine.” Mixed faces — broadly called “androgynous” — score lower on both masculinity and femininity sub-scores even if they’re attractive in absolute terms.

Why dimorphism is rewarded

The general finding in attractiveness research is “more dimorphic = more attractive, matched to sex.” A high-T male face and a high-estrogen female face are both rated more attractive than an androgynous baseline. The leading explanations:

1. Hormonal signal — dimorphic features indicate healthy hormone development through puberty, which is read as a fitness signal
2. Templatematching — humans pattern-match to clearer category exemplars; ambiguous category members get a slight penalty
3. Mate-selection bias — straight viewers reward dimorphic features in opposite-sex faces; this is by far the most replicated finding

There are exceptions — slight neoteny in male faces can be a positive in certain cultural contexts (K-pop, boy-band aesthetics) — but the overall pattern holds.

How it’s measured

You don’t measure dimorphism directly. You measure individual dimorphic features and combine them into a composite, weighted by how reliably each one separates male from female faces in a reference population. Fazly’s “Masculinity” or “Femininity” sub-score on a scan is exactly this — a weighted combination of jaw width, gonial angle, brow ridge, philtrum length, midface ratio, and eye geometry.

The output is sex-conditional: a male-presenting scan with masculinity = 8/10 is scoring well, a female-presenting scan with masculinity = 8/10 is scoring poorly. Same underlying features, opposite signs.

Can you change your dimorphism?

Bone structure is fixed past puberty, but several soft-tissue components are movable:

• Body fat — high body fat softens dimorphism in both directions (rounds male jaws, but also obscures female cheekbones)
• Muscle development — masseter, neck, trapezius growth amplifies male dimorphism
• Lip care, skin care — boost female dimorphism via lip fullness and skin smoothness
• Hair — beard adds to male dimorphism, soft framing hairstyles add to female

Surgical options exist on both sides. Facial feminization surgery and facial masculinization surgery are well-established procedures, primarily used in gender-affirming care but increasingly cosmetic.

What Fazly does

Every scan returns a sex-conditional dimorphism score, and the app flags which specific features are pulling you toward androgyny. The most common finding for male-presenting users: enough bone structure, but soft-tissue (body fat, beard, muscle) blunting it. For female-presenting users: enough bone, but skin and lip texture under-performing.

That breakdown tells you whether you’re a gym/diet/dermatology problem or a bone-structure problem — which decides whether the fix takes 3 months or a flight to Istanbul.