A computer assisted method for age-determination in non-literate populations

Abstract

Estimation of ages of individuals in censuses and genealogies is a serious problem for ethnographers working in populations without written birth records or systematic calendrical knowledge. The method of estimating ages, used by most anthropologists in such circumstances, has a high risk of inaccuracy. First, most of us have difficulty with estimation by this method in our own culture. Even though we know what middle-aged, or sixtyish people are supposed to look like, we are frequently surprised by substantial overor underestimation of ages when more accurate information becomes available to us. Secondly, our cultural age-stereotypes are not likely to help much in their application to members of another population. Few of us have any idea what sixtyish Melanesians are supposed to look like, so we are prone to apply the criteria supplied by our own cultures, however faulty they may be. Third, many environmental, economic and nutritional fac tors may affect the physical appearance of aging in immeasurable ways. One of us (Nelson) discovered, while recording census and genea logical data among the Kaimbi-speaking people of the New Guinea Highlands, that by use of the eyeball method he was rather consistently overestimating the ages of women and underestimating the ages of men. Most of the error was probably due to differential physical deterioration between males and females in the New Guinea Highlands. Because of heavy garden labor, poor nutrition, and protein loss through menstru ation, pregnancy and lactation, females ' age physically more rapidly than males. The discovery of this error led to a correction in the eyeball technique, though perhaps not a very systematic one. The error was discovered through comparisons of estimated ages with informants' statements regarding birth order of siblings and peership. The population in question is not age-graded, nor are there either male or female puberty rites, but each individual knows or can find out who his peers are and whether he is older or younger than another individual.