SCALING WITH SIZE IN HORSES MAY HAVE IMPLICATIONS FOR RECONSTRUCTING ACTIVITY FROM ENTHESEAL CHANGES
Channel: European Association of Archaeologists
Date: 02/11/2020

Size and scaling (the relative change in dimensions with size) affects structural durability and locomotor ability of vertebrate animals through effects on weight-bearing skeletal support system and muscle-tendon mechanics. This study examines scaling with size in horses representing a large range in size and type from small ponies to large draft horses in light of ostemetric dimensions focusing on the moment and load arm lengths of the ankle joint extensor muscles reconstructed from tarsal, metatarsal and phalangeal measurements. Results reveal that there is very little allometric scaling with size in this domestic species. For example, the moment arm length of the ankle extensors increases much less than predicted relative to their load arm length with size. Findings of this study are in an agreement with a study of pulling strength of draft horses, which shows that large horses are essentially isometrically scaled-up versions of small horses in respect to their ability to pull weight. Because the force output relative to body mass declines with size in horses, increasing size is associated with a compensatory increase in muscular effort. This largely isometric scaling with size may have implications for reconstructions of activities and/or workloads from entheseal changes. More entheseal change in large horses than in small horses is predicted.


Author(s): Niskanen, Markku (University of Oulu)