How could we determine age and sex by skulls in mass graves?
Age at death can be estimated from osteological standards associated with skulls, like pattern and timing of crown formation and tooth eruption in young individuals. First permanent molar tooth erupts at the age of six. The wisdom teeth erupt at the age of 18. Degree of suture closure in the skull also has bearing with age: sutures are more closed with increased age. After the age of 30, bones begin to wear down. Degree of bone and joint decay offers clues about approximate age of the individual. Degree of teeth wear and loss too depends upon degree of ageing. But caution is required here because the rate of tooth wear and loss is strongly related to diet. It is again difficult to determine the age of individuals older than 50 years.
Sex of an adult individual can be pinned down quite accurately from osteological standards associated with skulls. Adult male skull is usually more robust than adult female skull with heavier brow ridges over the eyes, larger mastoid processes and more prominent muscle attachment points especially in the occipital bones. Male skulls also tend to have squarer chins and eye orbits. Female eye orbits are roundish. Though the world population varies in robustness or degree of other tell-tale signs significantly, given a burial population, bio-archaeologists can discern between adult male and female skulls with more than 90% accuracy. The sex of a child skull is difficult to determine because the sexually distinctive characteristics of bones do not develop until young adulthood.