Evolutionary biology of nervous systems
The nervous system of human beings and other animals evolved over a long period of time about 1 billion to 530 million years. This is how the nervous system of humans and other species came into being. The human brain is more intelligent than that of most other species known on Earth at this present time. How and why it evolved to do more complex task than it's fellow ancestors like chimpanzees and other members of the primate family is not known and down to speculation and opinion. The neurotransmitters found in the human brain such as GABA (Gamma aspartic butyric acid) are found in bacterial life forms which is evidence for evolution of the human brain and the brain of other species from more primitive life forms.