Evolution of the Brain Over Eons of Time

Abstract

Neuroscience often explores the brain with a bottom-up approach, beginning from the fundamental unit of the neuron, and thence to structures, pathways, and networks. But an alternative way to explore the brain is top-down. Evolutionary neuroscience begins from the evolved functioning brain and deduces down to the individual kinds of brains as they developed through time. This top-down approach helps in understanding the broader context of changes that might not be understood by just looking at the brain as it is today. Chapter 11 describes how the study of evolution has helped to uncover brain–mind relationships. The chapter covers three main types of investigation: Fossils, comparative methods, and brain mechanisms. Fossils have brought better understanding of the human brain by noticing what is the same and different from the rest of the animal kingdom. Most of the structures in human brains are common to all species through time, but the human cortex is what sets us apart. Darwin’s single ancestor theory is described and the debate between intelligent design and self-organizing systems is discussed. More complex species evolved as a combination of branching like tree and climbing up a ladder. This chapter explains why the largest brain is not the smartest one, and how the triune brain with its three areas (lower brain, limbic system, and cortex) evolved through time. From what we learn of our past, we can build a better future.