Neoteny.

What neoteny means

Neoteny is a biology term for the retention of juvenile traits into adulthood. Salamanders that keep their gills, dogs whose floppy puppy ears never stiffen — those are neotenous. Applied to human faces, neoteny describes adults whose features look “younger” than their actual age:

• Large eyes relative to face width
• Small, slightly upturned nose
• Full, well-defined lips
• Short philtrum (vertical groove from nose to lip)
• Short midface (small distance from brow to nose base)
• Rounded forehead, no prominent brow ridge
• Soft, smooth skin with even tone
• Slightly recessed chin compared to adult male norms

You can have all of those at age 30. People who do consistently get rated younger than their chronological age, and — if female — significantly more attractive.

Why it works for female faces

Neoteny is one of the most robust findings in attractiveness research. Across continents and cultures, female faces rated most attractive tend to be more neotenous than the population average. The leading explanations:

• Estrogen signal — high estrogen suppresses the masculinizing facial growth that comes with testosterone during puberty. So a neotenous adult female face is, indirectly, a signal of higher estrogen.
• Fertility window — neotenous features peak in the late teens and early twenties, then decline. Reading them is reading age, which correlates with fertility.
• Universal infant template — humans are wired to find juvenile features compelling. That wiring leaks into adult-attractiveness judgment, especially toward female targets.

This is also why most A-list actresses retain neotenous features well into their 40s — large eyes, full lips, short midface — even if everything else about them aged normally.

Why it works against male faces

The whole point of male puberty is to add dimorphic features that move the face away from the juvenile template: brow ridge growth, jaw widening, gonial-angle sharpening, philtrum elongation, midface elongation (see sexual dimorphism). A neotenous adult male face is read as immature or under-masculinized, which drags down male attractiveness scores.

The asymmetry is striking:

• Female face, score 9/10: usually neotenous
• Male face, score 9/10: usually anti-neotenous (mature, dimorphic, large jaw, deep eyes)

Hunter eyes, sharp gonial angle, long midface, prominent brow — all anti-neotenous traits — are the male equivalent of the neoteny package.

How it’s measured

You can’t measure neoteny with one number. It’s a composite that includes:

• Eye-to-face-width ratio
• Lip-to-philtrum ratio
• Midface ratio (vertical proportion of midface to lower face)
• Forehead curvature
• Nose width and length
• Skin smoothness

Fazly’s “Youthfulness” sub-score on female-presenting scans weights these into a single number, and the same component pulls down a male-presenting scan’s masculinity sub-score. Same anatomy, opposite scoring depending on the sex of the face — that’s how dimorphic the trait is.

Can you become more neotenous?

Most neoteny is bone — fixed past puberty. But the soft-tissue and skin components are partly controllable:

• Skin care — clear, even-toned skin is the single biggest movable neoteny lever. Sunscreen, retinoids, and basic dermatology can move skin-age perception by 5–10 years.
• Body fat — slightly higher body fat fills out cheeks and lips, which reads younger. Extreme leanness on female faces often looks aged.
• Hairstyle — bangs and softer hair shapes around the face boost apparent neoteny.
• Lip care — hydrated, full lips push the score up.

Procedures like lip fillers, brow bone shaving, and chin reduction are the surgical route. They work, but they’re irreversible and often noticeable.

What Fazly does

The scan breaks “youthfulness” out from raw attractiveness so users can see which is driving their result. A female-presenting scan with high attractiveness and low neoteny tends to be a “striking” face that ages well; high attractiveness and high neoteny tends to be a “cute” face that peaks earlier. Knowing which you have is more useful than the overall number.

For male-presenting scans, Fazly flags any neotenous traits — recessed chin, short philtrum, round forehead — that are dragging down the masculinity score, so you know exactly what’s costing you points.