Abstract

Microscopic analysis of bones, teeth, and other animal hard tissue can yield considerable information. The most intensively studied of such structures are growth rings and osteons. “Growth rings” accrue to the periosteal surface of many bones as well as in teeth, reflecting annual and shorter periods. Where bone rebuilding has not destroyed them, they can often provide an accurate ageing device despite some problems with readability. The mandible is generally the best bone for this kind of ageing. Various vertebrates have been studied, with differing degrees of accuracy. “Osteons” refers to systems of conduits (and associated structures) for small blood vessels and nerves that grow and run lengthwise in much compact bone of many vertebrates. Osteons respond to the stress and strain of life, and this allows for their use in ageing bones. Various bones, e.g. femur, humerus, and rib, have been used with differing degrees of success and accuracy. Two general approaches are used: quantitative and qualitative. The latter, used in continental Europe, appears to be easier, more objective, and probably more accurate, but both consist of determining the relative frequency or area of various kinds of osteons, their parts and/or their fragments. Much less effective and concerted have been attempts to use osteons for sexing, though under certain conditions this can be done. The methods and techniques commonly used for studying osteons, including the preparation of thinsections with a microtome or taking of microradiographs, are not very difficult, but they do take some time to learn and to carry out. Advantages of using osteons include their being relatively resistant to fire and other abuses common to archaeological settings, their being able to be studied in small fragments of bones, and their presence in robust bones. Most but not all osteon work dealing with ageing and sexing has been done on human materials. A definite need exists for extending these efforts to more taxa, especially other long-lived ones and ones with marked sexual dimorphism.