The mark of captivity: plastic responses in the ankle bone of a wild ungulate (Sus scrofa)

Deciphering the plastic (non-heritable) changes induced by human control
over wild animals in the archaeological record is challenging. We
hypothesized that changes in locomotor behaviour in a wild ungulate due to
mobility control could be quantified in the bone anatomy. To test this, we
experimented the effect of mobility reduction on the skeleton of wild boar
(Sus scrofa), using the calcaneus shape as a possible phenotypic marker.
We first assessed differences in shape variation and covariation in
captive reared and wild caught wild boars, taking into account differences
in sex, body mass, available space for movement, and muscle force. This
plastic signal was then con-trasted with the phenotypic changes induced by
selective breeding in domestic pigs. We found that mobility reduction
induces a plastic response beyond the shape variation of wild boars in
their natural habitat, associated with a reduction in the range of
locomotor behaviors and muscle loads. This plastic signal of captivity in
the calcaneus shape differ from the main changes induced by selective
breeding for larger muscle and earlier development that impacted the pigs’
calcaneus shape in a much greater extent than the mobility reduction
during the domestication process of their wild ancestors.