The jaw and mandible
Gonial angle, bigonial and bicondylar width by sex, which jaw measures discriminate sex reliably, and how the jaw changes with age and dentition. Every figure attributed.
Range strips on one scale from 70 to 115 mm, each with a mean tick, a solid band at plus or minus one standard deviation and a pale band at plus or minus two. Female 91 ± 5.9; Male 97 ± 5.8.
Jaw & mandible
Range strips on one scale from 110 to 140 degrees, each with a mean tick, a solid band at plus or minus one standard deviation and a pale band at plus or minus two. Female 124.7 ± 3.2; Male 122.2 ± 3.9.
Landmarks: go gonion (jaw corner) · cdl condylion (top of the joint) · gn gnathion (chin)
Four numbers carry almost all of the jaw's shape information: the gonial angle (how square vs rounded the corner is), the bigonial width (jaw width at the corners), the bicondylar breadth (width across the joints) and the ramus height (vertical length of the back of the jaw). Bigonial width is widely used as one of the best single-bone sex discriminators.
| Measure | Female | Male | Range | Reads as |
|---|---|---|---|---|
| Gonial angle | 124.7° ± 3.2 | 122.2° ± 3.9 | 117-135° | <124° square · >126° rounded[5] |
| Bigonial width (Go-Go) | 91 ± 5.9 mm | 97 ± 5.8 mm | 85-105 mm | Farkas adult reference[2] |
| Bigonial (dry bone) | 87.4 ± 5.4 mm | 94.5 ± 5.3 mm | 76-109 mm | South Indian mandibles[1] |
| Bicondylar breadth | 108.2 ± 7.0 mm | 113.4 ± 5.5 mm | 90-125 mm | width across the joints[1] |
Mandibular measures, adults
Sex differences - the reliable part
- Males: higher ramus, more pronounced gonial angle (sharper, everted corner from heavier masseter attachment), larger inter-gonial width and a more distinct antegonial notch. Mandible-based sexing from 3D shape reaches ~91% accuracy.[3]
- Females: more obtuse (larger) mandibular angle, relatively wider ramus, and a more gracile body - a rounder, softer lower face.[3]
- Magnitude: the inter-gonial width difference lands around 7.6% in a well-matched sample.[3]
Age & dentition
The mandibular angle increases by roughly 3-7° from youth to old age, and alveolar bone resorbs after tooth loss, shortening the ramus and reducing chin projection.[6] A square young jaw reads increasingly rounded and receding with age.
Sources
- Sex Determination of Human Mandible Using Metrical Parameters (South Indian sample, n=250). pmc.ncbi.nlm.nih.gov/articles/PMC3919368
- Farkas adult craniofacial norms (gonial width M 97 ± 5.8 / F 91 ± 5.9 mm), as tabulated in Ogodescu et al. (2021), Updating Standards of Facial Growth. pmc.ncbi.nlm.nih.gov/articles/PMC8156684
- Chalazoniti, Lattanzi & Halazonetis (2024). Shape variation and sex differences of the adult human mandible. Sci Reports. www.nature.com/articles/s41598-024-57617-7
- Gonial Angle in Forensic Anthropology to Determine Age and Sex. pmc.ncbi.nlm.nih.gov/articles/PMC11288476/
- Gender Determination Using Mandibular Angle Measurement (mandibular angle M 122.19 ± 3.89 vs F 124.72 ± 3.24). brieflands.com/journals/amhsr/articles/114608
- Shaw & Kahn / Pessa: Changes in the Facial Skeleton With Aging. pmc.ncbi.nlm.nih.gov/articles/PMC3404279/