# 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. *Figure: 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.* Bigonial width by sex (Farkas adult reference). ## Jaw & mandible *Figure: 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.* Gonial angle by sex. 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] > **Conflicting direction - do not over-trust the angle alone.** The gonial angle is the least stable of the jaw measures, and the angles in the table above come from a single sample of 149 Iranian adult patients (cephalogram and panoramic radiograph).[5] One panoramic-radiograph study found males' angle about 5° *larger* than females' (124.7° vs 119.6°), while the geometric-morphometrics work above found the reverse.[4][3] Age and dentition move it more than sex does. Treat “females rounder” as the common case, not a law: **width measures discriminate sex far better than the angle does**. #### 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 1. Sex Determination of Human Mandible Using Metrical Parameters (South Indian sample, n=250). 2. 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.* 3. Chalazoniti, Lattanzi & Halazonetis (2024). *Shape variation and sex differences of the adult human mandible.* Sci Reports. 4. Gonial Angle in Forensic Anthropology to Determine Age and Sex. 5. Gender Determination Using Mandibular Angle Measurement (mandibular angle M 122.19 ± 3.89 vs F 124.72 ± 3.24). 6. Shaw & Kahn / Pessa: *Changes in the Facial Skeleton With Aging.* --- First published 2026-10-02, updated 2026-10-18. Web page: https://www.mackenziebowes.com/research/facial-character-parameters/jaw Part of [Facial parameters for character work: the dials that carry a face, and how far they travel](https://www.mackenziebowes.com/research/facial-character-parameters).