Overview
A long-standing model of brain evolution, characterized by the stacking of newer, rational layers atop an ancient "lizard brain," is being challenged. Research indicates that brain evolution might instead involve a dynamic equilibrium between two distinct styles of brain wiring. This process suggests that one wiring style expands while the other contracts, depending on an animal's specific requirements for survival.
Research Context
The traditional "lizard brain" concept posits a hierarchical evolution where a reptilian core is successively overlaid with more complex mammalian structures, culminating in the rational human neocortex. This model has influenced understanding of brain development for approximately seven decades. The current investigation re-evaluates this foundational understanding, proposing an alternative mechanism for evolutionary changes in brain architecture.
Findings
The study found that brain evolution does not appear to follow a simple stacking mechanism where newer, rational layers are added on top of an older "lizard brain" core. Instead, evolution appears to operate by balancing two competing styles of brain wiring. This balance involves the expansion of one wiring style concurrently with the shrinkage of the other. The specific wiring adjustments are dictated by what an animal requires to survive.