Distinguishing domestic pig femora and tibiae from wild boar through microscopic analyses

Abstract

Pigs are the only species where the geographical distribution of the domestic type overlaps with that of its wild ancestors. Therefore, distinction between domestic pig and wild boar remains are important to better understand the roles of these animals. The aim of this study was to distinguish domestic pig and wild boar femora and tibiae based on bone microstructure. Midshaft cross sections were prepared from femora (n = 15) and tibiae (n = 12) belonging to domestic pigs and wild boars. The bone tissue was classified and 300 osteons per animal were measured. Measurements included the perimeter, area, minimum and maximum diameters of osteons and Haversian canals, osteon density and lamellae count. Comparisons were made using a Kruskal–Wallis test. Domestic pig bone was mainly characterized by plexiform bone sandwiching a layer of irregular Haversian tissue, whereas wild boars exhibited a tissue transition from plexiform to irregular to dense Haversian tissue towards the subendosteal zone. A greater number of osteon lamellae were noted in the wild boars, with an increased number in tibiae compared to femora. Similarly, all metric parameters including osteon density were significantly larger in wild boars compared to domestic pigs except for the minimum diameter of the Haversian canal. Domestic pigs had more circularly shaped osteons and Haversian canals compared to the more elliptical shapes found in wild boars. Our results support the idea that a strong correlation exists between lifestyle and bone structure.