Spindle Neuron - Evolutionary Significance

Evolutionary Significance

The observation that spindle neurons only occur in a highly significant group of animals (from a human point of view) has led to speculation that they are of great importance in human evolution and/or brain function. Their restriction (among the primates) to great apes leads to the hypothesis that they developed no earlier than 15-20 million years ago, prior to the divergence of orangutans from the African great apes. The discovery of spindle neurons in diverse whale species has led to the suggestion that they are "a possible obligatory neuronal adaptation in very large brains, permitting fast information processing and transfer along highly specific projections and that evolved in relation to emerging social behaviors."p. 254 Their presence in the brains of these species supports this theory, pointing towards the existence of these specialized neurons only in highly intelligent mammals, and may be an example of convergent evolution.