Figure 4.

Velocity models of fetal and early postnatal brain growth in four precocial (a–d) and four altricial species (e–h). Colour bars indicate model estimates for the age of events associated with neurogenesis (green), tract formation (blue), and myelination (red) taken from www.translatingtime.net [9]. Birth timing is highly variable relative to growth. Altricial species tend to be born earlier along growth trajectories and correlated patterns of neurodevelopment, given that peak velocity corresponds well to eye opening (a common proxy for altriciality) during neurodevelopment (see text).