Some anthropometrics of the head12 Nov 2012
Anthropometry is the science of measuring the human body.
In this lab station, you’ll measure a few dimensions of your head. There are more than two dozen different standard measurements that anthropologists can take on the face and head. In the past, anthropologists often developed these measurements to study population relationships. These measurements are still used for many purposes, from designing well-fitting military helmets and developing facial recognition systems, to diagnosing developmental disorders in children.
- The maximum length of the head is taken from the midpoint of the brow, just above the bridge of the nose on the most prominent anterior projection of the frontal bone. This point is called glabella. With one point of the caliper here, the other should find the point on the back of the skull that opens the calipers to the maximum distance.
- The maximum cranial breadth is taken across the head from side to side, generally above the ears. These points are slightly different in every person, and the key is that the maximum breadth is found symmetrically, with the calipers at right angles to the anterior-posterior axis.
- The facial height is taken from the most posterior point on the center of the bridge of the nose (called nasion) to the lowest point on the midline of the jaw (called gnathion).
- The facial breadth is taken across the sides of the cheeks. Like the maximum cranial breadth, move the calipers until the most distant points perpendicular to the midline are found.
The cephalic index is the ratio of the maximum breadth to the maximum length of the head, taken externally. To calculate this index, divide the maximum breadth by the maximum length, and multiply by 100 (to obtain a percentage).
What to do: With a partner, measure your head for the four dimensions above and enter them into the spreadsheet.
The cephalic index has a long history in anthropology. The cephalic index was originated by the Swedish anatomist Anders Retzius, as an instrument to compare the cranial dimensions of living peoples of Europe with ancient skulls. Almost all human crania are longer than broad, and therefore the cranial index is nearly always less than 1. Various systems to divide crania into long-headed (dolichocephalic), medium-headed (mesocephalic) and round-headed (brachycephalic) were once used. The boundaries between these categories were somewhat arbitrary, and sometimes involved as many as eight grades of shape. In later years, the most widespread system of categorization classified a skull with cranial index greater than 80% as brachycephalic, less than 75% as dolichocephalic, and between 75 and 80% as mesocephalic.