How to calculate the age at formation of Harris lines? A step-by-step review of current methods and a proposal for modifications to Byers’ formulas

Abstract

Harris lines (HL; also known as “growth arrest lines” or “transverse radiopaque lines”) are horizontal sclerotic lines formed in the metaphyseal or diaphyseal part of long bones, usually visualized using X-ray images. Among the factors that may lead to a temporary arrest of bone growth (and thus—to HL deposition), the most commonly mentioned are nutritional disorders (malnutrition, protein, vitamin, and mineral deficiencies), a history of smallpox, pneumonia or other diseases, food poisoning, or alcohol abuse. The position of the HL is related to the period of incidence of physiological stress inhibiting bone growth, which enables the estimation of the age at which the subject was exposed to it. Such information can be valuable in the study on archeological populations; therefore, various methods have been developed to determine the age of HL deposition. In this review, six known methods for calculating the age of HL origin are presented and compared: Allison/McHenry, Hunt and Hatch, Clarke, Hummert and van Gerven, and Maat and Byers’ methods. In addition, the authors propose here a modification to the last method in order to enable calculations on non-adult bones.