Whales

The Whale Brain

An anatomical feature that scientists correlate with intelligence is the degree of folding of the upper surface of the whale’s brain, the area known as the cerebral cortex. This folding increases the surface area of the brain and is found in other intelligent animals, such as elephants and dogs. Whale brains generally show as much or more folding of the cerebral cortex as is seen in humans. Complex behavior may reveal more about whale intelligence than brain structure. Some whales in captivity exhibit extensive learning and problem-solving skills.

A study comparing brains, has found a certain type of neuron found in apes and humans and whales. There was also a considerable difference between the cortex neuronal structure in baleen and toothed whales. It is not known how these differences go to distinguish brain function and behaviour. Modular organisation of certain cells into groups, something found in other types of mammals but not in toothed cetaceans, was found in the baleen whale’s cortical brain. These structures promote faster and more efficient transmission between neurons.

The brain of an adult humpback whale was compared to the brain of a fin whale, and brains from several toothed whales, including the sperm whale, beluga whales and a killer whale. The result was found to be that the humpback’s cerebral cortex is similar to that of smaller sized cetaceans. However, there was substantial variability found between the cell structure of the cortex in humpbacks compared to toothed whales. The other notable feature was the presence of spindle cells in the humpback cortex in areas compared to other whales, and although the function of spindle neurons is not well understood, they are thought to be involved in cognitive processes and are affected by Alzheimer's disease and other debilitating brain disorders such as autism and schizophrenia. Spindle neurons are projection neurons, meaning that they connect one region of the brain to another and were given their name because of their spindle-like appearance. They have large cell bodies and, in the human cortex, occur in clusters of between 3-6 neurons.

Spindle neurons were also found in the same location in toothed whales in comparison with the largest brains, which suggests that they may be related to brain size. It is thought that spindle neurons probably first emerged in the ancestors of whales many years ago, as they are not found in the lesser apes or other species of primates. In spite of the relative scarcity of information on many cetacean species, whales such as the sperm whales, killer whales, and humpback whales have complex social patterns that included intricate communication skills, cooperation and cultural transmission. It is thus likely that some of these abilities are related to the complexity of brain organization in cetaceans.