The Intellectual Capabilities of the Human Brain

Snippets From Science

Compiled by Paul Burton

• Until about 10 years ago, it was thought that the intellectual capabilities of the human brain depended on the number of nerve cells, or neurons, making up the brain. It sounded simple enough, more neurons could make the difference between genius and you and me. Albert Einstein, a 20th century genius, died on April 18, 1955. A pathologist named Thomas Harvey quietly removed and preserved Einstein’s brain and appointed himself the brain’s guardian and protector.

Over the next 30 years or so Harvey doled out pieces of Einstein’s brain to several distinguished scientists skilled in the cellular anatomy of the nervous system. He hoped they might discover what made Einstein’s brain special. Could they discover genius in the cellular architecture of his brain? The anatomists carefully measured and counted neurons and other cells in various parts of Einstein’s brain, and then they compared the data to that obtained from the brains of a number of intellectually average people. They were surprised to find that the number and appearance of neurons in Einstein’s brain were similar to those found in the brain of an average person. (Fields, R.D., 2009, The Other Brain, Simon and Schuster)

• No one really knows exactly how many neurons there are in an average human brain. The estimates range from 10 billion to 100 billion neurons in the 3-pound mass of Jell-O-like tissue stuffed into our skulls. There is an even larger group of cells in the human brain that outnumbers neurons by a factor of about ten. These are glial cells, and they fill spaces around neurons.

Although neuroanatomists didn’t find any more neurons in Einstein’s brain than in yours or mine, they did discover that there were more glial cells associated with his neurons than in the average brain. This led to the theory that glial cells may play a role in the intellectual and creative capabilities of the brain. Could enhanced numbers of glial cells be the basis for Einstein’s genius? Maybe. Recent research studies focus on one of the four kinds of glial cells called astrocytes. These cells crowd in around neurons and abut synaptic junctions, the sites where one neuron signals to another.

Evidence is emerging that astrocytes can actually regulate synaptic transmission, which means that brain circuitry is not just a function of wiring, but also of how astrocytes enhance or suppress impulse transmission. Thus Einstein’s genius may have depended on the role astrocytes played in regulating brain circuitry associated with creativity. (Fields, R.D., The Other Brain)

• The drilling disaster in the Gulf of Mexico reminds us that the environment and many thousands of people are at the mercy of large corporations dealing with potentially hazardous materials. The world’s worst chemical disaster took place in December of 1984 at a Union Carbide pesticide plant in Bhopal, India, where human error resulted in the release of over 40 tons of methyl isocyanate gas.

The gas killed 5,295 people within days, and subsequently over 9,000 people died of complications from cyanide lesions. The cause of the accident was that plant personnel failed to activate three safety systems. Seven Union Carbide executives were implicated and sentenced to two years in prison, but the sentences were never served. The executives lived in the U.S. and managed to avoid extradition. Executives associated with corporate operations would do well to heed a statistical imperative that says, “if an event can theoretically happen, given enough time, it is certain to happen.” (Science, July 2, 2010)