NEW YORK: Brains of some species of whales have spindle neurons, the elongated nerve cells found in humans and some great apes and associated mostly with decision-taking and involved in higher cognitive functions like consciousness and expressing emotions, say U.S. scientists who have studied whales.
What is surprising is that these cells in whales were found located in the same region as in human brain and these were absent in smaller-brained whales and also in dolphins. Two of the whales which possessed spindle neurons are the humpback whale and the fin whale.
Two neuroscientists from Mount Sinai School of Medicine in New York City, Patrick Hof and Estel Van der Gucht, studied the detailed anatomy of whale brains and concluded that at least these two species indeed possessed spindle neurons in their brains. The team has reported its findings in The Anatomical Record.
Hof and Van der Gucht say when they compared the evolutionary histories of the species having and not having spindle neuron cells, they could estimate that whales evolved spindle neurons between 22 million and 30 million years ago -- nearly seven million years before the great apes evolved them.
The scientists describe the development process as convergent or parallel evolution and believe that some of the cognitive capabilities found in some whales -- they formed social groups and evolved a complex system of communication among themselves like singing -- could be possible with these spindle neurons.
The two wrote in the report, "In spite of the relative scarcity of information on many cetacean species, it is important to note in this context that sperm whales, killer whales, and certainly humpback whales, exhibit complex social patterns that included intricate communication skills, coalition-formation, cooperation, cultural transmission and tool usage."
Spindle neurons and their role in cognition were first discovered in 1999 when scientists established that humans and the great apes had this, though it was absent in all other primates. Subsequent research has said these cells are related to the power of decision-making and several other higher cognitive functions like learning, remembering and recognizing the world around.
The new study indicates the possibility that certain cetaceans and hominids may have evolved side by side.
It is believed that spindle neurons are affected in human disorders like Alzheimer's disease, autism and schizophrenia.
