Why Your Brain is Like a Chinchilla’s

Chart of brain scans of different mammals

As humans, we tend to have a bit of a superiority complex when it comes to comparing ourselves to other species, what with our opposable thumbs and all. But new research shows that the “connectivity” in our brains is the same as a chinchilla—or 122 other mammalian species.

Hopping Synapses

Connectivity is the neurological term for how information is passed along the information superhighway that is our brain. It is derived by observing how many synapses a thought or message must cross to get from its origin to its final destination in the brain.

To conclude that all mammals share the same brain connectivity, researchers out of Tel Aviv University used an MRI to scan the brains of 121 already deceased mammals that were supplied by the Kimron Veterinary Institute, as well as the brains of 32 living humans. This allowed them to build a database that reconstructed each species’s neural network. 

Network Theory

A mathematical process called Network Theory was then applied. This let the scientists standardize their measurements across vastly differently sized brains and count how many synapses were involved in transmitting the same signal, whether that signal was traveling through the brain of a dolphin, a bat, a person or,  yes, a chinchilla.

“Brain connectivity is a central feature, critical to the functioning of the brain,” said Yaniv Assaf of the School of Neurobiology, Biochemistry and Biophysics, and the Sagol School of Neuroscience at TU. He continued:

“Many scientists have assumed that connectivity in the human brain is significantly higher compared to other animals, as a possible explanation for the superior functioning of the ‘human animal. We know that key features are conserved throughout the evolutionary process,” added research partner Yossi Yovel of the School of Zoology, the Sagol School of Neuroscience, and the Steinhardt Museum of Natural History. “Thus, for example, all mammals have four limbs. In this project we wished to explore the possibility that brain connectivity may be a key feature of this kind—maintained in all mammals regardless of their size or brain structure. To this end we used advanced research tools.”

And those tools bore out the assumption that brains behave like brains no matter which species’ skull they lie beneath.

Smart Brains Conserve

An additional finding of the study was that all the brains exhibited what the researchers dubbed “Conservation of Brain Connectivity.” This is the idea that if there are a lot of neurological connections in each hemisphere of the brain, there are fewer connections between the hemispheres and vice versa. The finding held across all species studied, including humans.

“This mechanism ensures that high connectivity in a specific area of the brain, possibly manifested through some special talent (e.g., sports or music) is always countered by relatively low connectivity in another part of the brain,” said Assaf. “In future projects, we will investigate how the brain compensates for the enhanced connectivity associated with specific capabilities and learning processes.”

The research has been published in the journal Nature Neuroscience.