The average weight of the human brain is about 3 pounds, according to the Smithsonian Institution. In comparison, a chimpanzee's brain weighs less than a pound.
The brain consists of about 10 billion neurons, or nerve cells. Each of these nerve cells can make connections with about 10,000 other nerve cells, asserts Dr. Genevieve Orr of Williamette University.
The human brain has tripled in size during 7 million years of evolution, states Professor John Hawks from the University of Wisconsin-Madison. An early human ancestor, Australopithecus afarensis, had a brain capacity similar to apes of modern times. This brain capacity increased from the evolution from Homo habilis to H. erectus to H. sapiens, or modern humans.