Bipedalism and tool use

이족보행으로 인해 자유로워진 양손으로 도구를 제작하고 사용하게 되었고, 이에 따라 다른 사람의 손동작을 보고 따라하는 능력이 향상되었으며, 이 과정에서 Mirror neuron이 진화되었다.(Language evolution and human development).

타인의 행위를 따라하기 위해 타인의 행동과 자신의 행동을 일치시키기 위한 기능이 진화:

Rizzolatti, Fadiga, Gallese, and Fogassi has shown that monkeys have Mirror neurons in the supplementary eye fields of premotor cortex that respond with equal force when an action such as grabing is carried out either by the self or by the other, including a human. THis mechanism provides a way of equating actions performed by the self with actions or postures performed by the other. These neurons are part of the Dorsal visual system that allows us to represent the postural perspective of another in a way that is isomorphic with but nonidentical to our own postural perspective. This dorsal system for motor matching also connects to systems in motor cortex, Cerebellum, and Hippocampus that represent various postures and movements of the body. These system then connect to frontal mechanisms for storage and perspective shifting that provide a way of using our own full body image to perceive the actions of others. —p387, Origins of the social mind

계획을 세우고, 기억하고, 실행하는 기능이 진화:

The ability to imitate a series of actions requires construction of stored mental images of specific motor actions and postures. To plan the actions involved in chipping an axe, we must be able to call up an image of the desired product, and we must be able to sequence a long series of specific motions that are needed to locate good stones and devise methods for chipping edges. In this regard, the ability to construct a planned sequence of actions appears to be a unique property of hominids, as opposed to monkeys and apes. —p388, Origins of the social mind