“…By contrast, myelination is complete in white-matter tracts of pubertal macaques, and, although perhaps incomplete in pubertal chimpanzees (Sakai et al, 2010(Sakai et al, , 2011(Sakai et al, , 2012(Sakai et al, , 2013, myelination is complete when they are sexually mature (Miller et al, 2012). The life-span of rhesus macaques often exceeds 25 years, but they may show cognitive decline from as early as 12 years of age (Moore et al, 2006) in mid-life when also a reduction in white matter is detectable in dorsolateral prefrontal cortex and frontal, and anterior cingulate cortices of the monkeys (Dash et al, 2023;Kohama et al, 2012). Unlike them, protracted immaturity increasingly has defined the trajectory of cerebral evolution in Homo (Semendeferi and Hanson, 2016), and Coward (2012) suggested that prolongation during human ontogeny of an increase in cerebral white matter represents a significant phylogenetically evolved characteristic of our genus.…”