Humans have the rhinic, limbic, and supralimbic, with the neocortex covering the surface of the supralimbic. However, with cetaceans we see a radical evolutionary jump with the inclusion of a fourth segment. This is a fourth cortical lobe, giving a four-fold lamination that is morphologically the most significant differentiation between cetaceans and all other cranially evolved mammals, including humans. No other species has ever had four separate cortical lobes.
This well-developed extra lobar formation sandwiched between the limbic and supralimbic lobes is called the paralimbic. Considering neurohistological criteria, the paralimbic lobe is a continuation of the sensory and motor areas found in the supralimbic lobe in humans. According to Dr. Sterling Bunnell, the paralimbic lobe specializes in specific sensory and motor functions. In humans, the projection areas for different senses are widely separated from one another, and the motor area is adjacent to the touch area. For us to make an integrated perception from sight, sound, and touch, impulses must travel by long fiber tracts with a great loss of time and information. The cetacean's paralimbic system makes possible the very rapid formation of integrated perceptions with a richness of information unimaginable to us
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