CETACEANS
The Cetacean neocortex experienced many physiological and anatomical evolutionary adaptations to cope with surviving in an aquatic environment. Many marine mammals acquired strategies to manage ocean living and, in doing so, adapted to marine environments, but what makes the cetacean neocortex so different from terrestrial mammals?
This chapter will discuss the distinctions in cetacean neocortex functional architecture and how these evolutionary changes have benefited them for ocean living!
Fossil evidence shows that the morphological changes within the neocortex began during cetacean evolution 50 million years ago. Modern cetaceans have the largest brains in proportion to body size, and their structural complexity is related to cognition and sociality rather than adaptations to their marine environment.
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One of the most notable characteristics of the cetacean neocortex is the extreme amount of folding, which ensures maximized surface area within the confinement of the skull. The frontal operculum is correlated with speech in humans, coinciding with the insular cortex, which is involved in hearing and processing sound. In cetaceans, it is speculated that these areas serve similar functions, allowing for advanced communication and dialect between members of their own species. Their limbic lobe (the portion of the brain regulating behaviour, emotion, and memory) is significantly developed and more prominent than humans, which supports their ability to exhibit a range of various, well-developed emotions. Pathways involved in learning and spatial navigation are incredibly organized in comparison to terrestrial mammals. These adaptations benefit cetaceans for both hunting and surviving, echolocation and advanced auditory perception allows easier capture of prey. Socialization and communication allows cetaceans to connect with others, often travelling as groups for protection. Spindle cells (used by the limbic system for creating social systems and empathy) are also found in whales - it was thought that this trait was unique to the Great Ape and Humans when, in fact, whales actually contain a higher amount of spindle cells in their brain!
The image above depicts a human brain next to an orca brain, representing overall size and groove distinctions
This image depicts the dorsal (A) and rostral (B) along with another dorsal depiction (C) of the brain of a bottlenose. dolphin. Showing the orhanization of primary cortial areas. A1 - primary auditory cortex M1 - primary motor cortex
