Brain structures and life-span in primate species.

In haplorhine primates, when the effect of body weight is removed, brain weight is correlated with maximum recorded life-span. In this paper we have analyzed the relationships between volumes of specific brain structures and life-span. When the effect of body weight is removed, the volumes of many brain structures are significantly, positively correlated with maximum recorded life-span. However, the volumes of the medulla and most first-order sensory structures do not correlate with life-span. The cerebellum is the brain structure that best correlates with life-span. Parts of the cerebellum are particularly vulnerable to age-related loss of mass in humans. For another measure of the life cycle, female reproductive age, a similar set of brain structures is significantly, positively correlated (again with the exceptions of the medulla and most first-order sensory structures). There are some differences between the structures correlated for life-span and female reproductive age. For example, the hippocampus and lateral geniculate nucleus correlate with female reproductive age but do not correlate with life-span. In strepsirhine primates, when the effect of body weight is removed, total brain weight does not significantly correlate with either life-span or female reproductive age. However, the volumes of some brain structures in strepsirhines do correlate with these life-cycle parameters. The centromedial complex of the amygdala is the only structure to correlate with life-span in both strepsirhine and haplorhine primates. This structure participates in the regulation of blood pressure and in the stress response, which may be key factors governing life-span.