Sperm whale weighs 7,800g, the elephant's weighs 7,500g, man's weighs 1,500g, the dolphin's 840g, and the brain of a mouse weighs 0,4g
Role of Encephalization in Higher Brain Functions

brain weight (E) = K X body weight; K: encephalization factor

K: mouse: 0.06
chimpanziees: 0.3
human: 1.00

[Encephalization quotient in some familar mammals]

evolutionaly development:
relative increase in the neocortex --- reduction elsewhere in the brain due to decreasing sensory specialization & a need for fewer motor rsponse patterns

hunter and prey: progressive encephalization in vertebrates, carnivores

present brain wt: 200,000 years ago, 1,400 g

language about 40,000 years ago

Superior thinking and learning abilities<---- quantitative change, increase in the number of neuronal aggregates available for information processing