Mouth width : alar base width
Width of the mouth (commissure to commissure) as a multiple of nose width.
How to read it
the mouth is narrow relative to the nose for the reference group, or the nose is comparatively wide; the ratio does not distinguish which.
mouth width relative to nose width sits close to the reference mean.
the mouth is wide relative to the nose for the reference group.
Only 8.7% of a Southern Chinese sample conformed. Population means range from ~1.3 (African reference) to ~1.6 (NA White reference).
Conformity in published samples: east asian 9%
Reference values by population
| Reference population | Female (mean ± SD) | Male (mean ± SD) | n | Source |
|---|---|---|---|---|
| North American White | 1.599 ± 0.151 | 1.562 ± 0.15 | 2326 | Farkas 1994/2005 (NA White young adults) prov. |
| East Asian | 1.296 ± 0.124 | 1.273 ± 0.114 | 618 | Farkas 2005 (Chinese/Japanese/Vietnamese/Thai pooled); Jayaratne 2012 (Southern Chinese, n=103) prov. |
| South Asian | 1.418 ± 0.138 | 1.397 ± 0.136 | 210 | Farkas 2005 (Indian); Metgudmath 2022 prov. |
| African / African diaspora | 1.325 ± 0.126 | 1.299 ± 0.12 | 300 | Farkas 2005 (African-American, Zulu, Angolan) prov. |
| Middle Eastern | 1.508 ± 0.144 | 1.479 ± 0.141 | 348 | Farkas 2005 (Turkish, Iranian, Egyptian); Al-Sebaei 2015 (Saudi, n=168) prov. |
| Hispanic / Latino | 1.412 ± 0.139 | 1.392 ± 0.137 | 120 | Farkas 2005 (Mexican-American) prov. |
| Not specified — show pooled | 1.42 ± 0.189 | 1.394 ± 0.182 | 3922 | Unweighted pool of the six groups above prov. |
Where these numbers come from
Transcribed from the cited anthropometric literature; SDs of ratios are propagated conservatively (independence assumed). Entries marked prov. await line-by-line audit against the primary tables — see the norm provenance note.
Why every value has an error bar
Every value Canthion reports carries a 1σ uncertainty propagated from MediaPipe Face Mesh's published accuracy (3.96% of inter-ocular distance mean absolute error per landmark, Kartynnik 2019). For a typical 300 px inter-pupil photo that is ≈12 px per landmark, which is why small ratios and angles get wide intervals. A number without an interval is a number pretending to be more precise than it is.
References
- Farkas, Hreczko, Kolar & Munro (1985). Vertical and horizontal proportions of the face in young adult North American Caucasians: revision of neoclassical canons. Plast Reconstr Surg 75(3):328–338. pubmed.ncbi.nlm.nih.gov/3883374/
- Jayaratne, Deutsch, McGrath & Zwahlen (2012). Are Neoclassical Canons Valid for Southern Chinese Faces? PLoS ONE 7(12):e52593. doi.org/10.1371/journal.pone.0052593
- Farkas, Katic & Forrest (2005). International Anthropometric Study of Facial Morphology in Various Ethnic Groups/Races. J Craniofac Surg 16(4):615–646. doi.org/10.1097/01.SCS.0000171847.58031.9E
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