It is true that the neocortex is a remarkable structure, and scientists have long been interested in how it evolved. For a while, it was thought that the dorsal ventricular ridge (DVR) in reptiles might offer some clues, since it shares some functional similarities with the neocortex. However, recent research by scientists at Columbia University has shown that this view is incorrect. By analyzing patterns of gene expression in individual brain cells, the researchers were able to demonstrate that the neocortex in mammals and the DVR in reptiles are not related. Instead, it appears that mammals evolved the neocortex as an entirely new brain region, with no trace of what came before it. The neocortex is composed of new types of neurons that seem to have no precedent in ancestral animals. This research is important because it helps us to better understand the evolutionary history of the brain. It also highlights the importance of using new techniques and technologies, such as single-cell genomics, to explore the molecular details of biological systems. By doing so, we can gain insights that were previously impossible to obtain, and deepen our understanding of the natural world.
The research on the neocortex and the DVR is just one example of how the brain has evolved over time. Another study by Tosches and her colleagues in the same issue of Science showed that even ancient brain regions are evolving by getting rewired with new types of cells. This suggests that the brain is not a static organ, but rather a dynamic one that is constantly adapting to new environments and challenges. Furthermore, the discovery that gene expression can reveal important distinctions between neurons is prompting researchers to rethink how they define some brain regions and to reassess whether some animals might have more complex brains than previously thought. This is an exciting development, as it suggests that our understanding of the brain is constantly evolving and improving as new research techniques are developed and applied.