Wiley, R. H.   2018.   Evolution and self-awareness.   In: Shackelford, T., and V. Weekes-Shackelford (eds.), Encyclopedia of Evolutionary Psychological Science.   Springer International Publishing, Cham.   [6 pages]  



It seems clear to me that my subjective mental states are my own. Furthermore, this act of introspection shows that I have some ability to think about my mental states. I would say that I am self-aware. Furthermore, my experience indicates that most humans have such mental states of their own, including self-awareness. The question thus arises where do these subjective mental states, including self-awareness, come from? What causes or explains their presence and content? Has this human capability evolved?

Continuity between human and nonhuman animals

Studies of a number of nonhuman animals (especially chimpanzees, other apes, parrots, and dolphins) have indicated that these organisms can respond to complex stimulation, such as encoded queries and requests, in ways that resemble our own use of language. These studies are unusual among biological and psychological experiments in two ways: their small samples of subjects and their intensive involvement of humans. Nevertheless, there has been an accumulation of similar results with similar protocols, so that it is becoming more difficult to exercise broad skepticism about the kinds of responses evoked.

Interpretations of these responses often devolve into a polarity between attributing the observed responses to no more than thorough (rote) learning as opposed to the spontaneity or creativity that human language seems to show. There are twin problems here -- it is difficult to distinguish complicated from random patterns of responses and it is also hard to distinguish repeated from rote responses.

The issue of thorough learning, as opposed to volitional thought, is a pervasive problem in comparative studies of consciousness. Consider abilities to respond to oneself in a mirror and to attribute mental states to others (and by extension therefore to oneself). Even in humans these abilities clearly require learning. Humans nowadays master some superordinate associations involving mirrors that most nonhumans have not, but humans have not mastered all the possible associations. On the other hand, humans often master well-practiced tasks to the extent that they are performed unconsciously.

Neurophysiology of consciousness

Suggestive is an experiment that seems to reveal a half-second or so delay between the initiation of a spontaneous action, on one hand, and awareness of it, on the other. Such an experiment does not necessarily reveal that action precedes volition. Instead each of these two operations requires different neural events lasting finite, and evidently not exactly equal, amounts of time. Furthermore, the memory is encoded in language, which becomes the sole means of obtaining the datum actually recorded by the experimenter. Again we are back to questioning how we can know what another organism feels or thinks, unless that organism tells us in some way.

The inability so far to find a locus in the human brain specialized for consciousness has led to proposals that awareness results from distributed networks of neural interactions. Although some computer programs include "neural networks", it is still not clear how closely they resemble operations in a brain. Only at a superficially general level can we suppose that distributed operations in the brain share the features of computational "neural networks".

Continuity between brains and other machines

The relationship between consciousness and language also arises in proposals to distinguish humans from other machines -- or by extension to determine whether or not any machine is conscious. The issue is whether a

human (conscious) contestant can be distinguished reliably from a nonhuman (unconscious) one. Searle contends that Turing's test would not distinguish between a human who understood a language and one who just followed rules by rote. It thus could not distinguish a conscious human from an unconscious machine. By extension, it would also not distinguish between a conscious and an unconscious machine. A fundamental question here is whether or not conscious behavior, such as language, is strictly rule-following or not.

Noise as a determinant of consciousness

The evolution of consciousness thus depends in a fundamental way on the evolution of communication. It is thus remarkable that noise influences the evolution of communication in a way that provides a straightforward explanation for the evolution of subjective experience.

At the moment of perception a perceiver has no way to determine whether or not the perception corresponds to a particular external situation or to an erroneous illusion. All the perceiver knows at the moment is its perception. Nevertheless, memory of repeated perceptions, especially in combination with communication with other individuals, could reveal these discrepancies. In this way such an organism, capable of thought and language, could develop a sense that its own perceptions differed, in some respects and on some occasions, from those of others.

Because of noise in perception or communication, a perceiver or receiver must make a decision every time it acts on any sensation. It must decide whether the sensation warrants a response (and also which response). In other words, it must decide whether a sensation is a signal (with some relevance for the perceiver) or noise (with no, or misleading, relevance). Evolution by natural selection provides a mechanism that can optimize, within limits, neural capabilities to make decisions that promote survival and reproduction for the organism. In a fundamental way, nervous systems are decision-making organs.

Every organism must confront its subjectivity with some decisions, no matter how crude the mechanism. Awareness of subjectivity in perception, however, requires a nervous system to form higher-order associations. The evolution of this capability seems likely to have emerged gradually by successively more complex mental associations.


The mathematical analysis of optimal behavior in noisy situations thus indicates that (1) noise is an inescapable component of communication, (2) subjective awareness of self is a higher-order association of perceptions and responses, (3) decision-making is fundamental component of all communication and perception, and (4) both processes are as unpredictable as the unavoidable noise. An advantage of this analysis of the evolution of communication in noise is the framework it provides for addressing the questions posed at the start of this essay.

To account for the source and the content of self-awareness, previous discussion has always relied either on supernatural intervention or on vague neural operations on purified sensations. Supernatural intervention of course obviates any mechanistic explanation, including evolution. Response to pure sensations, on the other hand, leaves each organism encased in its own perceptions, without a way to distinguish between subjective and objective events.

The evolution of noisy communication, in contrast, shows that self-awareness (consciousness) results directly from the operations of nervous systems exposed to noisy sensations. The resulting explanation for self-awareness will require no unnatural or unspecified components.

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