Humpback whales have brain cells also found in humans

Cetaceans, the group of marine mammals that includes whales and dolphins, have demonstrated remarkable auditory and communicative abilities, as well as complex social behaviors. A new study published online November 27, 2006 in The Anatomical Record, the official journal of the American Association of Anatomists,compared a humpback whale brain with brains from several other cetacean species and found the presence of a certain type of neuron cell that is also found in humans. This suggests that certain cetaceans and hominids may have evolved side by side. The study is available online via Wiley InterScience at http://www.interscience.wiley.com/journal/ar.

Although the biology of the humpback whale is well understood, there have been virtually no studies published on its brain composition, leaving an open question as to how brain structure may relate to the extensive behavioral and social abilities of this mammal. Although brain to body mass ratio, a rough measure of intelligence, is lower for baleen whales such as the humpback compared to toothed whales such as dolphins, the structure and large brain size of baleen whales suggests that they too have a complex and elaborate evolutionary history.

Patrick R. Hof and Estel Van der Gucht of the Department of Neuroscience at Mount Sinai School of Medicine in New York, NY, examined the brain of an adult humpback whale and compared it with the brain of a fin whale (another baleen species) and brains from several toothed whales, including three bottlenose dolphins, an Amazon river dolphin, a sperm whale, two beluga whales, a killer whale and several other whale and dolphin species. They found that the humpback cerebral cortex, the part of the brain where thought processes take place, was similar in complexity to smaller sized cetaceans such as dolphins. The large area of cortex found in these mammals is thought to be related to acoustic capabilities and the current study shows that it is organized into a system of core and belt regions. However, substantial variability was found between the cell structure of the cortex in humpbacks compared to toothed whales. The authors suggest that these differences may indicate differences in brain function and behavior in aquatic species that are not yet understood.