The Origin of Consciousness in the Breakdown of the Bicameral Mind

The origin of consciousness in the breakdown of the bicameral mind, a 1976 book by Julian Jaynes, is probably one of the most intriguing and contentious works in the already unusually controversial field of consciousness studies. This book proposed bicameralism, the hypothesis that the human mind once operated in a state in which cognitive functions were divided between one half of the brain, which appears to be speaking, and another half which listens and follows instructions. Julian Jaynes’ central claim is that consciousness in humans, in the form that is familiar to us today, is a relatively recent phenomenon, whose development followed the invention of writing, the evolution of complex societies and the collapse of bicameralism. According to Jaynes, in the bicameral eras, humans attributed the origin of the inner voices (which we presumably all hear) not to themselves, but to gods. Human behavior was, therefore, not conscious but automatic. Actions followed from strict obedience to these inner voices, which represented orders from a personal god, themselves conditioned by social and cultural norms.

In Jaynes view, consciousness is strongly connected with human language (an assertion hard to refute but possibly an insufficiently general description) and results, in large part, from our ability to introspect, and to hold conversations and dialogues with ourselves. The change in human’s perception of these voices, a process which, according to Jaynes, took place over a time span that lasted only a couple of millennia, during the Babylonian, Assyrian, Greek and Egyptian civilizations (the ones he studied) led to the creation of consciousness as we know it today. This implies that human consciousness, as it exists today, is a brand new phenomenon, in the evolutionary timescale.

Taken at face value, this theory goes totally against the very ingrained belief that humans have been fully conscious for hundreds of thousands or even millions of years, if we consider other species of hominids and other primates. It is certainly strange to think that consciousness, as we know it, is a phenomenon with only a few millennia.

And yet, Jaynes’ arguments are everything but naive. They are, in fact, very sophisticated and based on extensive analyses of historical evidence. The problem with the theory is not that it is simplistic or that there is a lack of presented evidence. The problem I have with this theory is that the evidence presented comes mostly from a very subjective and argumentative analysis of historical artifacts (books, texts, vases, ruins), which are interpreted, in a very intelligent way, to support Jaynes’ main points.

To give an example, which plays an important role in the argument, let’s consider the Iliad. In this text, which predates, according to Jaynes, conscious behavior, and has its origins in bicameral times, all human actions derive, directly, from the clear and audible instructions received from gods. In the Iliad, there is no space for reflection, autonomy, cogitations, hesitations or doubts. Heroes and plain humans act on the voices of gods, and that’s it. The Odyssey and posterior texts are progressively more elaborate on human thought and motivation and (according to Jaynes) the works of Solon are the first that can be viewed as modern, consistent with our current views of human will and human consciousness. Most significant of all, to Jaynes, is the Bible, in particular the Old Testament, which he sees as the ultimate record of the progressive evolution of men from bicameralism to subjective, conscious, behavior.  Analysis of these texts and of other evidence of the evolution of consciousness in Mesopotamia, Assyria, Greece, and Egypt, are exhaustively presented, and should not be taken lightly. At the least, Jaynes may have a point in that consciousness, today, is not the same thing as consciousness, five millennia ago. This may well be true, and it is hard for us to understand human thought from that time.

An yet, I remained unconvinced of Jaynes’ main point. True, the interpretation he makes of the historical evidence is from someone who has studied the materials deeply and I am certainly unable to counter-argue with someone who is so familiar with the topics. But, to me, the many facts (thousands, probably) that he brings to bear on his argument can all be the result of many other factors. Maybe the writers of the Iliad wanted to use god’s voices for stylistic effect, maybe the empty throne of the Assyrian king Tukulti-Ninurta depicted in a famous scene is not due to the disappearance and silence of the gods (as he argues) but to some other reasons. Jaynes proposes many interesting and ingenious interpretations of historical data, but in the end I was not convinced that these interpretations are sufficient to support his main thesis.

Despite missing his main objective, however, the book makes for a great read, presenting an interpretation of ancient history that is gripping and enlightening, if not fully convincing.

The mind of a fly

Researchers from the Howard Hughes Medical Institute, Google and other institutions have published the neuron level connectome of a significant part of the brain of the fruit fly, what they called the hemibrain. This may become one of the most significant advances in our understanding of the detailed structure of complex brains, since the 302 neurons connectome of C. elegans was published in 1986, by a team headed by Sydney Brenner, in an famous article with the somewhat whimsical subtitle of The mind of a worm. Both methods used an approach based on the slicing of the brains in very thin slices, followed by the use of scanning electron microscopy and the processing of the resulting images in order to obtain the 3D structure of the brain.

The neuron-level connectome of C. elegans was obtained after a painstaking effort that lasted decades, of manual annotation of the images obtained from the thousands of slices imaged using electron microscopy. As the brain of Drosophila melanogaster, the fruit fly, is thousands of times more complex, such an effort would have required several centuries if done by hand. Therefore, Google’s machine learning algorithms have been trained to identify sections of neurons, including axons, bodies and dendritic trees, as well as synapses and other components. After extensive training, the millions of images that resulted from the serial electron microscopy procedure were automatically annotated by the machine learning algorithms, enabling the team to complete in just a few years the detailed neuron-level connectome of a significant section of the fly brain, which includes roughly 25000 neurons and 20 million synapses.

The results, published in the first of a number of articles, can be freely analyzed by anyone interested in the way a fly thinks. A Google account can be used to log in to the neuPrint explorer and an interactive exploration of the 3D electron microscopy images is also available with neuroglancer. Extensive non-technical coverage by the media is also widely available. See, for instance, the article in The Economist or the piece in The Verge.

Image from the HHMI Janelia Research Campus site.