en·ceph·a·li·za·tion 
(ĕn-sĕf′ə-lĭ-zāshən)
(ĕn-sĕf′ə-lĭ-zāshən)n.
Increase in the ratio of brain mass to body mass during the evolution of a species or other taxonomic group. Higher degrees of encephalization are generally correlated with higher degrees of intelligence.
en·cepha·lize v.