The monkey's brain is five centimeters big. According to relevant data, Lamarck's brain capacity is about 300 ml, and that of australopithecus africanus 3 million years ago was 440 cubic centimeters. 654.38+0 million years ago, the brain capacity of homo habilis was 600-650 cubic centimeters. About100-1500,000 years ago, the capacity of an upright human brain was 940 cubic centimeters. China's Lantian ape-man is about 654.38+0-800,000 years ago, with a brain capacity of 780 cubic centimeters. China Hexian ape-man lived about 240,000 to 280,000 years ago, and his brain capacity was 1.025 cubic centimeter, which was close to Zhoukoudian Peking ape-man. At present, the brain capacity of monkeys is only one-fifth of that of humans, about five centimeters.