1 Two critical advances were bipedalism and encephalization.

2 Based on the encephalization quotient, the brightest animals on the planet are humans, followed great apes, porpoises, and elephants.

3 We propose that human encephalization was made possible by a combination of stabilization of energy inputs and a redirection of energy from locomotion, growth and reproduction.

4 In the late 1970's the psychologist Harry J. Jerison developed an alternative measure that he called the Encephalization Quotien t or EQ.

5 They wondered about whether there had been evolutionary changes in the Encephalization Index.