What part of the brain distinguishes humankind from other animals?

"The cerebral cortex is the part of the brain that distinguishes humans from other species," explains the study's senior author Christopher A. Walsh, MD, PhD, a Howard Hughes Medical Institute investigator in the Neurogenetics Division at BIDMC and Bullard Professor of Neurology at Harvard Medical School. "And the frontal lobes are the part of the cortex that govern social function, cognition, language, and problem-solving. Patients with damage to the frontal lobes exhibit changes in behavior, and frontal lobotomies were once performed to alter aggressive behavior."

http://www.sciencedaily.com/releases/2004/03/040326073026.htm