a body can be a part of a robot & a computer controls a robot ->  a computer can control the body of a robot  an animal 's brain controls that animal & the brain is a part of the central nervous system ->  an animal's brain is a part of the nervous system that controls that animal  an animal's brain is a part of the nervous system that controls that animal & the nervous system is used for controlling the body ->  the brain can control animal body through the nervous system  a computer can control the body of a robot & the brain can control animal body through the nervous system ->  the computer in a robot and the brain in an animal both control the body of that robot / animal  the computer in a robot and the brain in an animal both control the body of that robot / animal & controlling is a kind of function ->  the computer in a robot and the brain in an animal both perform the function of controlling the body of that robot / animal  the computer in a robot and the brain in an animal both perform the function of controlling the body of that robot / animal & if two things perform the same function then those two things are similar -> the computer in a robot is similar to the brain in an animal