Intrinsic limb morpho‐dynamics and the early development of interlimb coordination of walking in a quadrupedal primate

Abstract

We question the developmental changes of the temporal aspects of quadrupedal walking and how these relate to the intrinsic morphological (size, shape) and dynamical (inertia) properties of the limbs and body. Indeed, during ontogeny of altricial species, a dependent infant develops toward autonomy. Interlimb coordination is likely to be mediated by the neurological system (central pattern generators and/or supraspinal control), whereas the mechanical parameters of limbs and body appear to influence the locomotor optimization of gaits. We studied six captive baboons at two instants in their development, when they just begin foraging independently and when they are autonomous, in order to collect, in parallel, morphometrics and temporal parameters of voluntary quadrupedal walking. The natural pendular period (NPP) is put forward to represent the limb's intrinsic morpho‐dynamics; the position of the body center of mass as the morpho‐dynamics of the body. The main results reveal that fore‐ and hindlimbs, at the level of the convergence of the NPP, have a significant and positive impact on the interlimb coordination pattern. This probably facilitates, very early in development, the control of the coordination. Nevertheless, because an improved control of the interlimb coordination points at a proceeding neuromotor maturation as well, neuromotor control appears to become gradually important relatively to the intrinsic morpho‐dynamics of the limbs during infancy. These findings are of importance in the context of the evolution of the locomotor developmental processes in primates.

The body center of mass in primates: Is it more caudal than in other quadrupedal mammals?

“…From this, they concluded that because monkeys maintain otherwise diagonal walking gaits, they should possess a caudal CoM. Although this hypothesis has been supported by ontogenetic studies showing parallel changes between the caudal migration of the BCoM and an increase use of the diagonal walking gaits (e.g., Grand, ; Nakano, ; Turnquist & Wells, ; Young, ), a certain number of works were not able to find such a relationship (e.g., Anvari et al, ; Druelle, Berillon, & Aerts, ; Young, Patel, & Stevens, ). Experimental alterations of the antero‐posterior mass distribution of the trunk revealed a clear influence on the mechanics of the limbs such as contact time, positioning, angular excursion, and compliance (e.g., Anvari et al, ; Lee, Stakebake, Walter, & Carrier, ; Young et al, ).…”

Developments in development: What have we learned from primate locomotor ontogeny?

“…For example, growing Papio cynocephalus experience an increase in frequency of DS relative to LS gaits around the time when the whole‐body COM moves caudal to the midline of the trunk (Shapiro & Raichlen, ). Druelle, Berillon, and Aerts () also found a caudal movement of COM with increase in use of DS for Papio anubis , but were hesitant to draw functional links between COM position and gait preference, pointing instead to the probable influence of neuromotor maturation. Young () found that in an ontogenetic sample of infant and juvenile squirrel monkeys, a caudal translation of the COM (from 47% to 58% of trunk length) during growth increased the probability of using a DS gait by 66% (on a flat surface) to 98% (on a pole).…”