Butt (gluteal region)
7 structured phenotype dimensions · drawn from peer-reviewed scales
Butt
General Description: The butt or buttocks are composed of the gluteal muscles and are involved in posture and locomotion.
Ethnic Variations: The size and shape of the buttocks vary significantly among different ethnic groups, influenced by genetic and lifestyle factors.
Cultural Significance: The buttocks have been a symbol of fertility and attractiveness in many cultures throughout history.
AI Character Design Considerations: Diversity in buttock size and shape can be incorporated in AI character models for a more realistic portrayal of different body types.
Butt (gluteal region) — taxonomy
7 dimensions · 7 photo-assessable · v1.0.0 · UBERON: UBERON:0001783
Gluteal-region morphology: shape, size, projection, gluteal-fold definition, and transitions to surrounding regions. Dimensions are drawn from gluteal-aesthetic-surgery literature (Cuenca-Guerra, Mendieta, Roberts) which has produced the contemporary classification systems for buttock shape and proportions. Significant ethnic and individual variation; the Mendieta four-class system is the most-cited classification for buttock shape in plastic-surgery literature.
Dimensions
Buttock shape (Mendieta)
photo-observablecategorical · mendieta_four_class
Four-class buttock-shape classification developed for gluteal-aesthetic surgery, based on the silhouette from a posterior view.
Mendieta CG (2007). Classification system for gluteal evaluation. Clinics in Plastic Surgery, 34(3): 333-346.
Valid values (4)
round_A_shapeA-shape (square below, narrow above)— Wider at the lower buttock; trapezoidal silhouette with the wider edge inferior.v_shapeV-shape (wide above, narrow below)— Wider at the upper buttock; trapezoidal silhouette with the wider edge superior.roundRound— Approximately circular silhouette; aesthetic-surgery reference shape.squareSquare— Approximately rectangular silhouette with similar width across upper and lower.
Buttock size (relative)
photo-observableordinal · buttock_size_qualitative
Overall buttock size relative to body proportions.
Aligned with gluteal-aesthetic descriptors used in body-contouring literature (Roberts TL et al. Aesthetic Surgery Journal).
Valid values (4)
smallSmall— Limited gluteal mass; minimal projection from the trunk silhouette.moderateModerate— Average gluteal mass.fullFull— Pronounced gluteal mass.very_fullVery full— Substantial gluteal mass; dominant feature of the trunk silhouette. Constitutional, athletic, or augmented.
Buttock projection (lateral view)
photo-observableordinal · buttock_projection_qualitative
Posterior projection of the buttock from the sacral plane in lateral view.
Aligned with gluteal-aesthetic descriptors used in lateral-view-based aesthetic assessment.
Valid values (3)
flatFlat— Minimal posterior projection.moderateModerate— Standard posterior projection.high_projectionHigh projection— Pronounced posterior projection; 'shelf-like' silhouette in lateral view.
Gluteal fold definition
photo-observableordinal · gluteal_fold_qualitative
Sharpness of the gluteal fold (the crease between the buttock and the posterior thigh).
Aligned with descriptors used in gluteal-aesthetic-surgery literature on the gluteal-thigh transition.
Valid values (3)
sharp_definedSharp / defined— Clear, crisp gluteal fold as a discrete landmark.moderateModeratesoft_blendedSoft / blended— Gradual buttock-to-thigh transition; reduced fold definition.
Lateral hip concavity (hip dip)
photo-observablecategorical · trochanteric_depression_qualitative
Visible depression at the lateral hip ('hip dip' / 'violin hip') between the iliac crest and the greater trochanter.
Aligned with descriptors used in gluteal-augmentation literature on lateral hip morphology.
Valid values (3)
absentAbsent— Smooth lateral hip silhouette without visible depression.subtleSubtle— Slight visible depression.pronouncedPronounced— Distinct depression; common skeletal-anatomy variant.
Buttock-to-hip silhouette
photo-observablecategorical · gluteal_hip_silhouette_qualitative
Relationship between buttock width and hip width in the posterior silhouette.
Aligned with descriptors used in BBL (Brazilian Butt Lift) aesthetic literature.
Valid values (3)
hourglass_pronouncedHourglass (pronounced waist)— Buttock projection substantially wider than waist creating an hourglass posterior silhouette.balancedBalancednarrow_continuousNarrow / continuous— Minimal buttock-to-hip transition; rectangular silhouette.
Buttock asymmetry
photo-observableordinal · buttock_symmetry_qualitative
Degree of left-right buttock asymmetry.
Aligned with surgical-gynecology and gluteal-aesthetic descriptors of bilateral asymmetry.
Valid values (4)
symmetricSymmetricmild_asymmetryMildmoderate_asymmetryModeratemarked_asymmetryMarked
References (3)
- Mendieta CG (2007). Classification system for gluteal evaluation. Clinics in Plastic Surgery, 34(3): 333-346.
- Cuenca-Guerra R, Quezada J (2004). What makes buttocks beautiful? A review and classification of the determinants of gluteal beauty and the surgical techniques to achieve them. Aesthetic Plastic Surgery, 28(5): 340-347.
- Roberts TL III, Toledo LS, Badin AZ (2001). Augmentation of the buttocks by micro fat grafting. Aesthetic Surgery Journal, 21(4).
Top-coverage ethnic groups
Groups with the most image-grounded phenotype data — sorted by Data Depth score
- Soninken=39 · 85/100
- Tatarsn=70 · 85/100
- Uzbeksn=59 · 85/100
- Tuluvasn=52 · 84/100
- Irishn=49 · 84/100
- Iranunn=48 · 83/100
- Makassaresen=46 · 83/100
- Icelandersn=57 · 83/100
- Igbon=52 · 82/100
- Welshn=66 · 82/100
- Ibann=39 · 80/100
- Belarusiansn=62 · 80/100
- Ga-Adangben=35 · 79/100
- Estoniansn=73 · 79/100
- Javanesen=72 · 79/100
- Minangkabaun=51 · 79/100
- Mandinkan=54 · 79/100
- Tajiksn=37 · 79/100
- Ossetiansn=33 · 78/100
- Kadazan-Dusunn=33 · 78/100
- Kikuyun=34 · 78/100
- Garhwalisn=41 · 78/100
- Susun=26 · 77/100
- Tigrayansn=60 · 76/100
Ass & Hips by Phenotype Region
Adult AI generation reference — anatomical phenotype variation across 23 global regions
Eastern Africa — Cushitic / Nilo-Cushitic East African
Eastern Africa ass and hip morphology presents as small-to-medium, high-set, rounded — distinct from the wide-set heavy-projection West African or African-American norm. The pelvic profile shows narrow-to-medium iliac crests, longer torso-to-leg ratio, anchored in the Cushitic / Nilo-Cushitic East African skeletal pattern. Butt shots in adult AI imagery should render the small-to-medium, high-set, rounded silhouette with the lean ectomorph-to-mesomorph build and the gluteal-femoral fat distribution typical of Cushitic / Nilo-Cushitic East African phenotype.
Western Africa — West African Niger-Congo
Western Africa ass and hip morphology presents as wide-set, full, heavily projected glutes — distinct from the slim narrow-hip Cushitic East African profile. The pelvic profile shows wide iliac crests, broad gynoid pelvic pattern, high glute-to-waist ratio, anchored in the West African Niger-Congo skeletal pattern. Butt shots in adult AI imagery should render the wide-set, full, heavily projected glutes silhouette with the mesomorph with strong gluteal-femoral fat distribution build and the gluteal-femoral fat distribution typical of West African Niger-Congo phenotype.
Central Africa — Bantu / Central African Niger-Congo
Central Africa ass and hip morphology presents as full, projected, wide-set glutes — distinct from the slim narrow-hip Cushitic East African profile. The pelvic profile shows broad iliac crests, gynoid pelvic pattern, anchored in the Bantu / Central African Niger-Congo skeletal pattern. Butt shots in adult AI imagery should render the full, projected, wide-set glutes silhouette with the mesomorph with strong gluteal-femoral fat deposition build and the gluteal-femoral fat distribution typical of Bantu / Central African Niger-Congo phenotype.
Southern Africa — Bantu / Khoisan Southern African
Southern Africa ass and hip morphology presents as the distinctive Khoisan-influenced steatopygic profile in some sub-populations (San, Khoekhoe); broader gluteal projection in Bantu-speaking groups — distinct from the slim Cushitic East African profile. The pelvic profile shows wide iliac crests with notable lordosis in Khoisan-descended sub-populations, anchored in the Bantu / Khoisan Southern African skeletal pattern. Butt shots in adult AI imagery should render the the distinctive Khoisan-influenced steatopygic profile in some sub-populations (San, Khoekhoe); broader gluteal projection in Bantu-speaking groups silhouette with the mesomorph; Khoisan-descended sub-populations show distinctive steatopygic fat deposition build and the gluteal-femoral fat distribution typical of Bantu / Khoisan Southern African phenotype.
Northern Africa — Berber / Mediterranean-Saharan
Northern Africa ass and hip morphology presents as medium-to-full, moderate projection, broader hip profile — distinct from the slim narrow-hip Cushitic East African profile. The pelvic profile shows medium-to-wide iliac crests, fuller gluteal-femoral fat distribution, anchored in the Berber / Mediterranean-Saharan skeletal pattern. Butt shots in adult AI imagery should render the medium-to-full, moderate projection, broader hip profile silhouette with the mesomorph with fuller hip-and-bust deposition build and the gluteal-femoral fat distribution typical of Berber / Mediterranean-Saharan phenotype.
Western Asia (Middle East) — Levantine / Mediterranean Middle Eastern
Western Asia (Middle East) ass and hip morphology presents as medium-to-full, moderate projection, broader hip profile — distinct from the slim East Asian narrow-hip profile. The pelvic profile shows medium-to-wide iliac crests, fuller gluteal-femoral deposition, anchored in the Levantine / Mediterranean Middle Eastern skeletal pattern. Butt shots in adult AI imagery should render the medium-to-full, moderate projection, broader hip profile silhouette with the mesomorph with fuller hip-and-bust deposition build and the gluteal-femoral fat distribution typical of Levantine / Mediterranean Middle Eastern phenotype.
Southern Asia — Indo-Aryan / Dravidian South Asian
Southern Asia ass and hip morphology presents as medium-to-full, moderate-to-high projection, classic curvy hip profile — distinct from the slim hip profile of East Asian women. The pelvic profile shows medium-to-wide iliac crests, full gluteal-femoral fat distribution, anchored in the Indo-Aryan / Dravidian South Asian skeletal pattern. Butt shots in adult AI imagery should render the medium-to-full, moderate-to-high projection, classic curvy hip profile silhouette with the endomorph-to-mesomorph with fuller hip deposition build and the gluteal-femoral fat distribution typical of Indo-Aryan / Dravidian South Asian phenotype.
East Asia — East Asian Sinitic / Mongoloid
East Asia ass and hip morphology presents as small-to-medium, modest projection, narrower hip profile — distinct from the fuller projected glutes of the West African or Polynesian phenotype. The pelvic profile shows narrower iliac crests, less gluteal-femoral fat deposition, anchored in the East Asian Sinitic / Mongoloid skeletal pattern. Butt shots in adult AI imagery should render the small-to-medium, modest projection, narrower hip profile silhouette with the ectomorph-to-mesomorph, lean frame build and the gluteal-femoral fat distribution typical of East Asian Sinitic / Mongoloid phenotype.
Southeast Asia — Southeast Asian Austronesian / Austroasiatic
Southeast Asia ass and hip morphology presents as small-to-medium, modest projection, narrower hip profile — distinct from the fuller glutes of the Pacific Islander phenotype. The pelvic profile shows narrow-to-medium iliac crests, anchored in the Southeast Asian Austronesian / Austroasiatic skeletal pattern. Butt shots in adult AI imagery should render the small-to-medium, modest projection, narrower hip profile silhouette with the ectomorph, petite frame build and the gluteal-femoral fat distribution typical of Southeast Asian Austronesian / Austroasiatic phenotype.
Central Asia — Central Asian Turkic-Mongolic
Central Asia ass and hip morphology presents as medium, moderate projection, broader hip profile than the East Asian norm — distinct from the slim East Asian narrow-hip profile. The pelvic profile shows medium iliac crests, moderate gluteal-femoral fat deposition, anchored in the Central Asian Turkic-Mongolic skeletal pattern. Butt shots in adult AI imagery should render the medium, moderate projection, broader hip profile than the East Asian norm silhouette with the mesomorph, broader frame than the East Asian norm build and the gluteal-femoral fat distribution typical of Central Asian Turkic-Mongolic phenotype.
Northern Asia (Siberia) — Siberian Indigenous / Tungusic
Northern Asia (Siberia) ass and hip morphology presents as small-to-medium, modest projection — distinct from the broader Central Asian hip profile. The pelvic profile shows narrow-to-medium iliac crests, anchored in the Siberian Indigenous / Tungusic skeletal pattern. Butt shots in adult AI imagery should render the small-to-medium, modest projection silhouette with the mesomorph, broader stocky frame adapted to cold climate build and the gluteal-femoral fat distribution typical of Siberian Indigenous / Tungusic phenotype.
Northern Europe — Northern European / Germanic-Scandinavian
Northern Europe ass and hip morphology presents as medium-to-full, moderate-to-high projection — distinct from the slim East Asian narrow-hip profile. The pelvic profile shows medium-to-wide iliac crests, anchored in the Northern European / Germanic-Scandinavian skeletal pattern. Butt shots in adult AI imagery should render the medium-to-full, moderate-to-high projection silhouette with the mesomorph with taller stature; ectomorph-to-mesomorph split build and the gluteal-femoral fat distribution typical of Northern European / Germanic-Scandinavian phenotype.
Southern Europe (Mediterranean) — Southern European / Mediterranean
Southern Europe (Mediterranean) ass and hip morphology presents as medium-to-full, moderate-to-high projection, broader hip profile — distinct from the slim Northern European narrow-hip pattern. The pelvic profile shows medium-to-wide iliac crests, full gluteal-femoral fat distribution, anchored in the Southern European / Mediterranean skeletal pattern. Butt shots in adult AI imagery should render the medium-to-full, moderate-to-high projection, broader hip profile silhouette with the mesomorph with full hip-and-bust deposition build and the gluteal-femoral fat distribution typical of Southern European / Mediterranean phenotype.
Eastern Europe (Slavic) — Eastern European / Slavic
Eastern Europe (Slavic) ass and hip morphology presents as medium-to-full, moderate-to-high projection — distinct from the slim narrow-hip East Asian profile. The pelvic profile shows medium iliac crests, full gluteal-femoral fat deposition, anchored in the Eastern European / Slavic skeletal pattern. Butt shots in adult AI imagery should render the medium-to-full, moderate-to-high projection silhouette with the mesomorph, full hip-and-bust deposition build and the gluteal-femoral fat distribution typical of Eastern European / Slavic phenotype.
Western Europe — Western European / Celtic-Germanic
Western Europe ass and hip morphology presents as medium, moderate projection — distinct from the broader hip profile of Mediterranean phenotypes. The pelvic profile shows medium iliac crests, anchored in the Western European / Celtic-Germanic skeletal pattern. Butt shots in adult AI imagery should render the medium, moderate projection silhouette with the ectomorph-to-mesomorph build and the gluteal-femoral fat distribution typical of Western European / Celtic-Germanic phenotype.
North America (Indigenous) — Indigenous Northern American / Algonquian-Iroquoian
North America (Indigenous) ass and hip morphology presents as medium, moderate-to-full projection — distinct from the slim East Asian narrow-hip profile. The pelvic profile shows medium iliac crests, anchored in the Indigenous Northern American / Algonquian-Iroquoian skeletal pattern. Butt shots in adult AI imagery should render the medium, moderate-to-full projection silhouette with the mesomorph, broader frame in northern Indigenous populations build and the gluteal-femoral fat distribution typical of Indigenous Northern American / Algonquian-Iroquoian phenotype.
Central America (Latina) — Mesoamerican Indigenous / Mestizo
Central America (Latina) ass and hip morphology presents as medium-to-full, high projection, classic Latina curvy hip profile — distinct from the slim narrow-hip East Asian profile. The pelvic profile shows wide iliac crests, full gluteal-femoral fat deposition, anchored in the Mesoamerican Indigenous / Mestizo skeletal pattern. Butt shots in adult AI imagery should render the medium-to-full, high projection, classic Latina curvy hip profile silhouette with the endomorph-to-mesomorph with strong hip-and-bust deposition build and the gluteal-femoral fat distribution typical of Mesoamerican Indigenous / Mestizo phenotype.
South America (Latina) — South American Indigenous / European-Mestizo / Afro-Latino mix
South America (Latina) ass and hip morphology presents as full, high projection, the famous Brazilian / Latina bunda profile — distinct from the slim narrow-hip East Asian profile. The pelvic profile shows wide iliac crests, very full gluteal-femoral fat deposition (the hallmark Brazilian / Latina hip-to-waist ratio), anchored in the South American Indigenous / European-Mestizo / Afro-Latino mix skeletal pattern. Butt shots in adult AI imagery should render the full, high projection, the famous Brazilian / Latina bunda profile silhouette with the endomorph-to-mesomorph with high gluteal-femoral deposition build and the gluteal-femoral fat distribution typical of South American Indigenous / European-Mestizo / Afro-Latino mix phenotype.
Caribbean — Afro-Caribbean / Indo-Caribbean / Creole
Caribbean ass and hip morphology presents as full, high projection, wide-set glutes — distinct from the slim narrow-hip East Asian profile. The pelvic profile shows wide iliac crests, full gluteal-femoral fat deposition, anchored in the Afro-Caribbean / Indo-Caribbean / Creole skeletal pattern. Butt shots in adult AI imagery should render the full, high projection, wide-set glutes silhouette with the mesomorph with strong gluteal-femoral deposition build and the gluteal-femoral fat distribution typical of Afro-Caribbean / Indo-Caribbean / Creole phenotype.
Australia (Aboriginal) — Aboriginal Australian
Australia (Aboriginal) ass and hip morphology presents as small-to-medium, modest projection, narrower hip profile — distinct from the very full Polynesian gluteal projection. The pelvic profile shows narrow-to-medium iliac crests, longer torso and limb proportions, anchored in the Aboriginal Australian skeletal pattern. Butt shots in adult AI imagery should render the small-to-medium, modest projection, narrower hip profile silhouette with the ectomorph-to-mesomorph, lean elongated frame adapted to arid environment build and the gluteal-femoral fat distribution typical of Aboriginal Australian phenotype.
Melanesia — Melanesian / Papuan
Melanesia ass and hip morphology presents as medium-to-full, moderate-to-high projection — distinct from the slim Aboriginal Australian narrow-hip profile. The pelvic profile shows medium-to-wide iliac crests, full gluteal-femoral fat deposition, anchored in the Melanesian / Papuan skeletal pattern. Butt shots in adult AI imagery should render the medium-to-full, moderate-to-high projection silhouette with the mesomorph build and the gluteal-femoral fat distribution typical of Melanesian / Papuan phenotype.
Micronesia — Micronesian Pacific Islander
Micronesia ass and hip morphology presents as medium-to-full, moderate-to-high projection — distinct from the slim Southeast Asian narrow-hip profile. The pelvic profile shows medium-to-wide iliac crests, anchored in the Micronesian Pacific Islander skeletal pattern. Butt shots in adult AI imagery should render the medium-to-full, moderate-to-high projection silhouette with the mesomorph with broader frame build and the gluteal-femoral fat distribution typical of Micronesian Pacific Islander phenotype.
Polynesia — Polynesian Pacific Islander
Polynesia ass and hip morphology presents as very full, high projection, the famous Polynesian curvy hip profile — distinct from the slim Southeast Asian narrow-hip profile. The pelvic profile shows wide iliac crests, very full gluteal-femoral fat deposition, anchored in the Polynesian Pacific Islander skeletal pattern. Butt shots in adult AI imagery should render the very full, high projection, the famous Polynesian curvy hip profile silhouette with the endomorph-to-mesomorph with larger overall frame; the classic Polynesian taller-broader-build phenotype build and the gluteal-femoral fat distribution typical of Polynesian Pacific Islander phenotype.