But a few years ago Dr. Patrick Gannon of the Mount Sinai School of Medicine in New York found the same asymmetry in chimpanzee brains.

Compared to the chimpanzee brain, the human brain is larger and certain brain regions have been particularly altered during human evolution.

Research into the chimpanzee brain has revealed chimp communication activates an area of the chimp brain in the same position as Broca's area, a language center in the human brain.

Relative to its body size, the crow brain is the same size as the chimpanzee brain.

However, since A, afarensis had a chimpanzee brain in a body half the weight of a chimpanzee, its brain/body ratio was twice that of a chimpanzee.

In terms of cognitive function - thinking and reasoning - the chimpanzee brain is significantly more limited than its human counterpart.

The gulf between the human and the chimpanzee brain may be smaller than that between the human and the rat brain, but it is still large.

A few years ago, Dr. Gannon and his colleagues were examining preserved chimpanzee brains with the same methods used in the 1968 study.

Of 18 chimpanzee brains examined, 17 had enlarged plana temporale on the left side of the brain.

For instance, Dr. Conroy has since found that a fossil hominid skull reported to have a 440-cubic-centimeter brain really measures only 370 cubic centimeters, about the size of a chimpanzee brain.