A model of developmental canalization, applied to human cranial form

Developmental mechanisms that canalize or compensate perturbations of organismal development (targeted compensatory growth) are widely considered a prerequisite individual health and the evolution complex life, but little is known about nature these mechanisms. It even unclear if how “target trajectory” encoded in organism’s genetic-developmental system or, instead, emerges as an epiphenomenon. Here we develop statistical model developmental canalization based on extended autoregressive model. We show under certain assumptions strength amount canalized variance population can be estimated, at least approximated, from longitudinal phenotypic measurements, target trajectories unobserved. extend this to multivariate measures discuss reifications ensuing parameter matrix. apply approaches geometric morphometric data human postnatal craniofacial size shape well frontal sinuses. Craniofacial showed strong during first 5 years leading 50% reduction cross-sectional variance, followed by continual increase puberty. Frontal sinus size, contrast, did not any signs canalization. Total decreased slightly until age increased thereafter. However, different features very dynamics. Whereas relative dimensions nasopharynx throughout development, facial orientation continually variance. Some signals may owe independent variation timing cranial components, our results indicate evolved, partly mechanically induced ensure properly sized upper airways dimensions.