AANS Neurosurgeon | Volume 27, Number 1, 2018


Study Sheds Light on Evolution of the Brain

In a paper published in the journal Nature, written by researchers from Princeton University and Bell Labs, a study conducted on the evolution of the brain revealed how the brains of humans and other mammals are related to one another across evolution. During the study, the researchers compared the relative sizes of 11 brain parts and revealed a unique brain structure for each species. They calculated the percentage of total brain volume contributed by each part and created the term “cerebrotype” to describe the resulting 11-number characterization, just as the word “genotype” describes the unique DNA sequence for each species. The analysis showed how mammals fall into a spectrum of cerebrotypes, with humans at one end and insect-eaters, such as hedgehogs, at the other. The findings support the “social intelligence” theory of primate evolution, which holds that pre-human ancestors were at an advantage for survival if they excelled at complex social dynamics, such as working in groups and predicting the behavior of others. Researchers based their work on a 20-year-old database assembled by German researchers who catalogued information about the brains of 300 animals.  For example, previous studies showed that one brain area, the neocortex, grew rapidly over the course of evolution, expanding from 16 percent of the brain in insect-eaters to 80 percent in humans. The neocortex is responsible for social interactions, reasoning and other complex cognitive tasks, suggesting that the outcome of social interactions has been a powerful evolutionary force. To read more about this study, click here.


Second International Brain Mapping Course
April 26-27, 2018; New Orleans

Surgical Approaches to Skull Base
April 26-28, 2018; St. Louis, MO

2018 AANS Annual Scientific Meeting
April 28-May 2, 2018; New Orleans

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