Abstract:

Thyroid cartilage, as the largest laryngeal cartilage, is occasionally found in ancient human bone materials from archaeological sites after ossification, and has a certain indicative role in judging the sex and age of ancient residents. This paper is a study of 18 individual cases of ossified thyroid cartilage discovered from the ancient human bones excavated from six archaeological sites in Shandong province combining with modern medicine and forensic medicine. The 18 individuals spanned four dynasties from the Shang Dynasty to the Qing Dynasty, and 1 case belongs to the Shang Dynasty, 10 cases to the Han Dynasty, 1 case to the Ming Dynasty, and 6 cases to the Qing Dynasty. Among the 18 individuals, 14 cases were males, 3 cases were females, and 1 case could not be identified for sex. Among the 17 cases with certain age, 15 cases were the age range of 35~50 years, 1 case was around 30 years old, and 1 case was older than 60 years old.

The ossified thyroid cartilage in ancient human bone material is mostly found in the middle, lower edge, posterior edge, superior and inferior horn. These parts are early and highly ossified and are easier to preserve. Excluding acquired defects, individual ossification of the right and left lateral thyroid cartilage was preserved in a symmetrical pattern. There is a gender difference in the way and the size thyroid cartilage is ossified. In males, the anterior horn of the thyroid cartilage is preserved, most commonly at the lower end of the anterior horn, and the male protruding "laryngeal node" can be observed in the fully ossified anterior horn. In females, the anterior horn was generally absent, with incomplete ossification of the middle part of the bone plate, and the measurement of the inferior margin was significantly smaller than that in males.

Eighteen individuals had only partially ossified thyroid cartilage, and none of them had completely ossified thyroid cartilage. Even the better preserved individual M195 of Xinzhi cemetery still has unossified areas at the posterior edge of the right plate. The ossification pattern of thyroid cartilage varies significantly among individuals. Although the ossification of thyroid cartilage correlates with age, it has a very low accuracy when used for identification. The results of age estimation using thyroid cartilage are older than that using bioarchaeology. It is not advisable to independently use the ossification of thyroid cartilage as a standard for age judgment. Still, it can be used as a reference basis to assist in age estimation. Among the 18 ancient residents, all individuals with a certain age were older than 30 years old.

Key words: thyroid cartilage, ossification, gender differences, age estimation