“perhaps it isn’t a real problem at all, but a ghostly remnant of a past dualistic way of thinking.
“Brains and consciousness did not evolve to create theologies, but as enhanced survival strategies in an unforgiving world…Feinberg and Mallatt argue that the seeds of consciousness lie in the very origins of life on Earth, more than 3bn years ago…
Not of course the rich subjectivity with which the word is imbued today, but what they call sensory consciousness, the ability to respond to and act on the external environment, as when their present-day successors – single-celled animals such as amoeba – detect and navigate towards food sources and withdraw from noxious ones. Even such single-celled creatures behave as if they have a sense of bodily integrity, their membranes studded with molecular receptors which can recognise the difference between themselves and something that is not-self. This is where the authors’ neuroevolutionary path to human consciousness begins.
For single-cell organisms, the path from sensory input to motor response is direct and unmediated. For multicellular creatures things get more difficult; sense inputs must be able to signal to distant motor organs – originally through molecules chemically similar to today’s hormones. But nervous systems are faster and more specific, providing a direct private line between the two.
Feinberg and Mallatt draw on fossil evidence and the nervous systems and behaviours of the present-day successors to these long-extinct creatures to document this evolutionary history. For them, the crucial moment comes with the emergence of brains, which group together what was previously a diffuse nervous system into a tight cluster of nerve cells and their connections; no longer are sensory inputs and motor outputs directly linked but are separated by several “hidden layers” of nerve cells, making possible vastly richer possibilities of interconnection and the storage and recall of experience – learning and memory. These clusters are the precursors to modern brains.
They date this transition to the great Cambrian explosion of novel life forms that occurred about 550m years ago. Before then, animals were essentially vegetarian, grazing on the great oceanic beds of algae. The new life forms of the Cambrian included predatory carnivores. Hunting for food required new skills and sharper senses, and vegetarians needed new defence mechanisms. An evolutionary arms race drove the search for bigger and better brains, enhanced senses and faster motor coordination and responses. After much hesitation, the authors settle on the lamprey as the poster-organism for this key step. Lampreys? Eel-like creatures that live by biting into their prey and sucking out their blood. Bishop Wilberforce, who when confronted with Darwin’s evolutionary theory so famously objected to being descended from a monkey, would have been appalled at the thought that all his high flown theological rhetoric had such humble evolutionary origins.
From the lamprey’s proto-brain to the vastly more complex and richly connected brain of mammals, then primates and humans, the evolutionary lineage is well charted. And as brains become more complex, making possible not just direct responses to the external environment but also reflection on it, so sensory consciousness becomes enriched, and the basic distinction between self-not-self transmuted into a recursive self-awareness….their neuroevolutionary approach is the best we will have if we are to respect the power of our own human consciousness and also to locate it within a biological framework. As they cheerfully admit, neuroevolution does not solve the “hard problem”. But then perhaps it isn’t a real problem at all, but a ghostly remnant of a past dualistic way of thinking.