Elephant brain. Part I: gross morphology, functions, comparative anatomy, and evolution

Area of Science:

• Neuroscience
• Comparative Anatomy
• Evolutionary Biology

Background:

• Elephant brains (Loxodonta africana and Elephas maximus) exhibit unique morphological characteristics.
• Previous studies have highlighted the significant size and complexity of elephant brains relative to body mass.

Purpose of the Study:

• To provide detailed morphological data on African and Asian elephant brains.
• To compare elephant brain structure with that of primates, carnivores, cetaceans, and humans.
• To explore the evolutionary implications of elephant brain morphology and its relation to cognitive abilities.

Main Methods:

• Morphological analysis of brains from four African and three Asian elephants.
• Comparison of observed data with existing scientific literature.
• Presentation of 20 figures illustrating elephant brain anatomy, with 16 figures containing new material.

Main Results:

• Elephant brains display a highly complex gyral pattern, exceeding that of primates and carnivores.
• Well-developed cerebral lobes (frontal, parietal, temporal, limbic, insular) and a disproportionately large temporal lobe were observed.
• Elephant brains are the largest among terrestrial mammals (average 4783 g), with a significant neonatal brain size and a large cerebellum.
• Encephalization quotient has increased significantly over evolutionary time.
• Similarities in brain structure and cognitive functions (tool use, complex learning) between elephants and humans suggest convergent evolution.

Conclusions:

• Elephant brain morphology, particularly the large cerebral cortex and temporal lobe, underpins their complex learning and behavioral skills.
• Convergent evolution may explain shared traits between elephant and human brains, reflecting adaptation to complex environments and behaviors.
• The study provides valuable insights into the neuroanatomical basis of intelligence in non-primate mammals.