Veterinary graduate probes how evolution shapes the brain
His study focused on three mammals: the African elephant, the humpback whale and the Florida manatee
Luigi Michele Zahra has recently completed his studies at the University of Veterinary Medicine in Budapest. His thesis questioned how the brain adapts when animals evolve to live in very different environments.
Entitled ‘Morphological and physiological differences in the cerebellum of aquatic and terrestrial mammalians’, his research explored the cerebellum, the part of the brain responsible for coordinating movement, balance and certain cognitive functions. Although the cerebellum has a remarkably similar structure across vertebrates, small differences in the size and shape of its neurons may reveal how species adapt to their surroundings.
His study focused on three very different mammals: the African elephant, the humpback whale and the Florida manatee. Elephants live entirely on land, while whales and manatees have evolved to spend their lives in water. Elephant and manatee also share a common ancestor and are each other’s genetically closest extant species. By comparing these species, the project aimed to investigate whether aquatic and terrestrial lifestyles are reflected in the microscopic architecture of the brain.
Instead of studying physical brain tissue, the research relied on an international scientific database called NeuroMorpho.org, which stores detailed digital reconstructions of neurons from many species.
Using programming tools in Python and specialised neuroscience software, Zahra examined three types of cerebellar interneurons: basket cells, stellate cells and Lugaro cells. Using these tools allowed him to measure characteristics such as cell body size, dendrite thickness and branching patterns. The simulations also tested how effectively these neurons respond to incoming signals.
The results revealed clear differences between species. In many cases, elephant neurons had larger cell bodies and thicker dendrites, suggesting a higher capacity for signal integration. Whale neurons, on the other hand, tended to show lower activation probabilities in the simulations. Manatees often displayed intermediate characteristics between the two.
However, the findings also showed that the story is more complex than a simple aquatic versus terrestrial divide.
While differences between species were evident, they could not be explained solely by lifestyle.
Other factors, such as overall brain size, evolutionary history and specialised behaviours, may play an important role.
For example, elephants possess the largest relative cerebellum of any mammal, which is thought to support the extremely fine motor control required for their trunks.
By combining comparative biology with computational neuroscience, this research offers a small window into how evolution shapes the brain at the cellular level.
Studies like this help scientists better understand how neural circuits adapt to different environments and behaviours across the animal kingdom.
This research was made possible thanks to the Veterinary Studies Scholarship Scheme funded by the government of Malta, which supported Zahra for his six years of studies.