One of the last great scientific frontiers of our time involves the attempt to describe how the biology of our brains gives rise to the elusive concept of consciousness. Attempts to define consciousness in itself have been the subject of endless scientific and philosophical conjecture, contributing to the difficulties of even getting agreement among experts in the field on what problems need to be addressed. For the purpose of their thesis, the authors have approached consciousness, not as a thing, but rather a process, and attempt to account for human consciousness in terms of well established biological principles.
Any biological theory that aims to account for the myriad functions of the human brain must comfortably accommodate Darwin's theory of evolution by natural selection. As the evolutionist, Theodosius Dobzhansky, has commented, "nothing in biology makes sense except in the light of evolution". Consequently, the "dynamic core" hypothesis posited in this work to account for a number of the features of consciousness includes natural selection as a major foundation.
Consciousness takes the reader on a journey across epochs of time to demonstrate how a one-dimensional linear code (DNA) can specify a three-dimensional living brain which, at a fundamental level, is wholly dependent on the outside world. Although necessary, genes are insufficient to describe the integration and differentiation of neurons (cellular units of the brain) into functional clusters or "dynamic cores". The existence of human consciousness more accurately derives from cellular activities at the population level rather than a relatively simple biochemical description beginning with DNA. Through no fault of their own, but more as a consequence of the subject matter itself, we are left at the end of the book with more questions than we had at the start. Could it be any other way?
Nowhere do the opposing traditions of reductionism and holism become as vividly juxtaposed as in the neural sciences. Describing what it means to think, remember and communicate will ultimately involve the incorporation of many diverse approaches to solve the same problem. The molecular description of the mechanics of a single thought remain light years away and, if the authors are correct, such descriptions, when they come, should employ a novel vocabulary to reflect the complexity of how a thought is executed, sustained and communicated.
Gearoid Tuohy is a researcher at the Wellcome Ocular Genetics Unit, Trinity College Dublin.