Humans vs. other animals
Overall brain size doesn't correlate with level of intelligence. For instance, the brain of a sperm whale is more than five times heavier than the human brain but humans are considered to be of higher intelligence than sperm whales. The more accurate measure of how intelligent an animal may be is the ratio between the size of the brain and the body size, according to the University of California San Diego's Temporal Dynamics of Learning Center.
Among humans, however, brain size doesn't indicate how smart someone is. Some geniuses in their field have smaller- than-average brains, while others larger than average, according to Christof Koch, a neuroscientist and president of the Allen Institute for Brain Science in Seattle. For example, compare the brains of two highly acclaimed writers. The Russian novelist Ivan Turgenev's brain was found to be 2,021 grams, while writer Anatole France's brain weighed only 1,017 grams.
Humans have a very high brain-weight-to-body-weight ratio, but so do other animals. The reason why the human's intelligence, in part, is neurons and folds. Humans have more neurons per unit volume than other animals, and the only way to do that with the brain's layered structure is to make folds in the outer layer, or cortex, said Eric Holland, a neurosurgeon and cancer biologist at the Fred Hutchinson Cancer Research Center and the University of Washington.
"The more complicated a brain gets, the more gyri and sulci, or wiggly hills and valleys, it has," Holland told Live Science. Other intelligent animals, such as monkeys and dolphins, also have these folds in their cortex, whereas mice have smooth brains, he said.
Humans also have the largest frontal lobes of any animal, Holland said. The frontal lobes are associated with higher-level functions such as self-control, planning, logic and abstract thought — basically, "the things that make us particularly human," he said.
Left brain vs. right brain
The human brain is divided into two hemispheres, the left and right, connected by a bundle of nerve fibers called the corpus callosum. The hemispheres are strongly, though not entirely, symmetrical. The left brain controls all the muscles on the right-hand side of the body and the right brain controls the left side. One hemisphere may be slightly dominant, as with left- or right-handedness.
The popular notions about "left brain" and "right brain" qualities are generalizations that are not well supported by evidence. Still, there are some important differences between these areas. The left brain contains regions involved in speech and language (called the Broca's area and Wernicke's area, respectively) and is also associated with mathematical calculation and fact retrieval, Holland said. The right brain plays a role in visual and auditory processing, spatial skills and artistic ability — more instinctive or creative things, Holland said — though these functions involve both hemispheres. "Everyone uses bot
Physical Facts About the Brain
The adult human brain weights about 3 pounds and the cerebrum accounts for about 85% of the brain. The brain is composed of 40% gray and 60% white matter. The gray matter is made up of about 100 billion neurons that gather and transmit signals while the white matter is made of dendrites and axons that the neurons use to transmit signals. The brain is composted of about 75% water and is the fattiest organ in the body, consisting of a minimum of 60% fat. Humans have the largest brain to body ratio of any animal, and the blood vessels in the brain, if stretched end-to-end, would be about 100,000 miles long. The neocortex, or language center of the brain, comprises about 76% of the organ.
The Developing Brain
Brain development begins very early in the life of a fetus. The brain grows at a rate of about a quarter million neurons per minute in the first trimester, with brain growth continuing through age 18. The brain of a newborn baby triples in size during the first year. The amount of brain stimulation a child receives can effect brain growth by as much as 25%. If continued mental activity takes place, new neurons will develop throughout the life of a brain.
Brain Function
Brains use about 20% of the total blood and 20% of the total oxygen that is circulating through the body at any given time. If blood supply to the brain is cut off for more than 8 to 10 seconds, loss of consciousness will occur, yet the human brain can survive for between 4 and 6 minutes without any oxygen. The information processing speed of the human brain can reach up to 120 meters per per second, and in a waking state can generate 10 - 23 watts of energy.
The brain is all this and more, providing us with the ability to bond socially with other humans and giving us the facilities for the creativity that makes us the innovators of the animal kingdom.
Amazing
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