Morphofunctional effects of captivity on the microanatomy of the talus bone in a wild ungulate (Sus scrofa)

Captive environments induce plastic and adaptive phenotypic changes to the inner and outer anatomy of vertebrate bones. However, the respective effects of these changes are not well documented. This study examines the impact of captivity on the microanatomy of the talus, an ankle bone that lacks muscular attachment but is involved in supporting the body weight during locomotion. This study focuses on the wild boar (Sus scrofa) as a wild ungulate model and on an experimental setting through which these wild boars experienced different mobility patterns during their growth: 20 lived in their natural habitat, while 21 were born in the wild but raised in captivity, either in a large enclosure (10) or in a stable (11). We quantitatively investigated the microanatomical structure of their talus using 3D cartographies of compact bone thickness and five microanatomical parameters, while describing the distribution of compact bone and the trabecular network from the cartographies and virtual sections. While the absolute thickness of compact bone remains similar regardless of the mobility context, specimens that have been raised in captivity have tali with greater bone density and a tighter network of bone trabeculae but a lower relative maximum thickness of compact bone. Our results show that captivity induces a plastic response in the bone microanatomy, which could therefore serve as a valuable indicator of the early process of domestication of wild boars and, more generally, wild ungulates in the bioarchaeological records.