There is no such thing as a gold standard for determining age in clinical medicine. There are several testing methods used in medicine to deduce age: based on human tissue morphology, bone X-ray testing, morphological changes in human bones, and chemical changes in human tissues. 1. Inferring age according to human tissue morphology: the changes in the human epidermis infer age, as people grow older, a network of protrusions is formed at the junction of the epidermis and dermis of the skin, which is developed in young people and shrinks and fades in the elderly. By detecting the value of parallel bands in the epidermis and the value of network protrusions and comparing with the value of the sample of the known age layer to make age inference. 2. Bone X-ray test to infer age: (1) Age is inferred by studying the development of ossification centers in bones, and the age sequence of the appearance and healing of the ossification centers on X-ray. (2) Inferring age by dental X-ray, inferring age by determining the age of the tooth based on calcification of the root, changes in tooth development in the pulp chamber, and crown index. 3. Morphologic changes in the human skeleton: (1) Inferring age based on bone length, using the length of the diaphysis of the radius and femur to infer the age of young children, and using the data on the relationship between the length of the sternum and the height of minors to infer age. (2) Inferring age from morphological changes in the cranium, inferring the age of the minor’s cranium by changes in the cranium at each stage of development. Inferring the age of the adult cranium by the ageing changes of the cranium, the degree of healing of the cranial sutures, and the time and order of eruption of teeth. 4. Changes in human tissue chemistry: Determine the D/L ratio of aspartic acid in human tissue to find out the relationship with age.