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The Great Debate: Minds, Genes and Consciousness

Minds, Genes and Consciousness

by Caspar Hewett

Natural selection - the filter which only allows the genes of those individuals who live long enough to successfully reproduce to reach the next generation. An idea first expounded by Darwin in On The Origin of Species.

Sexual selection - the filter which only allows the genes of those individuals who are attractive enough to members of the opposite sex to successfully reproduce to reach the next generation. An idea first expounded by Darwin in The Descent of Man and Selection in Relation to Sex.

Adaptation - A physical or behavioural characteristic which confers a survival or reproductive advantage on an organism.

What bearing does evolutionary theory have on questions of the human mind? In recent years there has been a plethora of new theories regarding the human mind and consciousness, many with an evolutionary argument underlying them. There are two questions which are central to all of these theories; how and why a mind such as ours evolved; and what characterises the human mind. In the 1970s sociobiology attempted to explain modern human behaviour as adaptive, while in contrast Richard Dawkins introduced the idea of the meme, a unit of cultural transmission or imitation analogous to the gene which describes how culture evolves independently of genes; an idea which has recently been developed by Susan Blackmore in her book The Meme Machine (1999). The new discipline of evolutionary psychology (EP) has also emerged, which argues that our minds are adapted to our environment of evolutionary adaptedness (EEA), and thus we should be able to explain human mental attributes in terms of the advantages they conferred on our ancestors of 100,000 years ago living on the African savannahs.

The question of brain size is one important factor in the evolution of the human mind. Three million years ago our ancestor the upright ape Australopithecus afarensis, also known as Lucy, had a brain size of about 400cc, while modern humans have a brain size of about 1400cc - a remarkable 3˝ times the size. This large brain is very costly to run; 18% of our energy expenditure is consumed by the brain. From a Darwinian perspective this suggests that there must have been significant and immediate advantages to possessing a larger brain which outweighed the expense. So, why the large brain?

Many have attempted to answer this question. Some suggest that accumulated knowledge played a crucial rôle in allowing our ancestors to develop a rich, varied diet, which in turn required the capacity for language and for a large memory. Others argue that a sexual preference for juvenile features drove us towards prolonged retention of such features (neoteny) which in turn allowed the development of a larger brain as a secondary effect of a longer period of growth. The Machiavellian hypothesis proposes that the main evolutionary pressure for an increase in intelligence was competition with other people; the primary function of most animal communication is to manipulate others, not just to impart information; the ability to deceive and to detect deception in others is highly important for many social animals; thus it is reasonable to assume that this principle underlies the evolution of our highly developed communicative ability. Taking this a step further Robert Trivers has argued that we developed a subconscious because, in order to be really convincing to others in our deception, it became necessary to develop the ability for individuals to deceive themselves;. In a similar vein Nicholas Humphrey argued that the need to guess the likely actions of other individuals required us to develop the capability to imagine what is in others' minds; a theory of mind, which was a key factor in the development of self- consciousness. Some argue that sexual selection is the driving force behind the explosion in brain size which took place in our species (see for example Matt Ridley The Red Queen, Geoffrey Miller The Mating Mind).

To examine any of these theories a clear idea of what consists a human mind and of what we mean by consciousness is necessary. Daniel Dennett's book, Kinds of Minds: Towards an Understanding of Consciousness is a good start point for such definitions. In it he takes an evolutionary perspective, looking at the minds of animals and attempting to understand why natural selection favoured the development of minds such as ours.

Dennett draws attention to the advantages and pitfalls of the intentional stance. The intentional stance is the position we often intuitively take when we analyse animal behaviour. For example it is hard to resist describing the behaviour of a hare on spotting a fox in the following terms: If the fox is far enough away for the hare to be confident that it can escape if pursued it stands on its hind legs to allow the fox to see it and to see that it is aware of the fox's presence. The hare then returns to whatever it was doing without running away, confident that the fox will leave it alone, which it invariably does! While the rationale for its actions may be real, we must be aware that the hare itself has no inkling of that rationale. Dennett describes this as "free floating" rationale.

Dennett develops the idea that the mind consists of not just the brain, but the combination of all the transducers and receptors distributed throughout the body. Transducers are devices that take information in one medium and translate it into another, an example in our own bodies is the eardrum, an human-made example would be its artificial equivalent, the microphone. Effectors are devices that are directed by a signal to make something happen, for example to bend an arm or close a pore. The nervous system, then, can be thought of as an information network tied at transducer and receptor nodes to the body. The network itself comprises the mind, the brain is just one of many organs which acts to further the interests of the body it resides in: "My body contains as much of me, the values and talents and memories and dispositions that make me who I am, as my nervous system does." He describes the brain as "a relatively recent usurper of control." He goes on to argue that the materials that make up a mind matter - both for speed reasons and because of the vast number of transducers and effectors spread throughout the nervous system.

Evolution embodies information in every part of an organism. This information can be exploited by the nervous system without it having to be copied into the brain. Thus there is wisdom, especially about personal preferences, residing in the rest of the body. Sometimes the old controls can interfere with our decision-making and seem to be acting in competition with our minds - it is sometimes irresistible to think of our body as having a second mind, a 'mind of its own' in such circumstances. So, why should we have developed what appears to be more than one mind? Dennett suggests that the most obvious reasons are speed and sophistication.

Dennett proposes the following stages in the evolution of conscious minds. He concentrates on the development of the ability to predict future and the ability to take the intentional stance.

1. Darwinian Creatures - Various simple organisms are blindly generated and natural selection insures that only the best designs survive.

2. Skinnerian Creatures - Individual organisms that are not wholly designed at birth: they have phenotypic plasticity. Such organisms would use simple trial and error to establish how best to deal with a new situation. (after B.F. Skinner)

3. Popperian Creatures - Such animals have the ability to preselect among a variety of possible behaviours or actions. This requires some sort of filter which amounts to an internal environment or model of the external environment. However, Popperian creatures allow the body to inform decision-making. (after Karl Popper)

4. Gregorian Creatures - Organisms whose inner environments are informed by the designed parts of the outer environment. (after Richard Gregory) For example scissors are an endower of intelligence.

Popperian creatures would be expected to make much smarter moves than their Skinnerian counterparts, partly because they are adaptively responsive to a wider range of high fidelity information. However it is only at the level of Gregorian creatures that organisms can benefit from others' experience.

Dennett makes some general points about minds and what constitutes them:

1. Curiosity must drive any powerful learning system. He points out that, in addition to being herbivores or carnivores, animals are informavores.

2. We are not the only Popperian creatures.

3. Surprisingly mind-like behaviour can be generated by fairly simple, mechanical control systems that bear little or no resemblance to what we think of as a mind.

4. The evolution of distal discrimination - olfaction, hearing, vision. The bodies of organisms which developed these abilities became intricate networks of specialised internal agents designed by natural selection to receive all the information available at the peripheries of the body.

Dennett examines other factors he considers necessary prerequisites to the development of the human mind:

* Tool use is a two-way sign of intelligence - It requires intelligence to recognise, use and maintain a tool, but tools themselves also confer intelligence on the organisms which possess them. Probably the most important tools humans use is a mind-tool - language.
* Tracking - The ability to track an object is a prerequisite for high-quality perception. Further, many creatures need the ability to track and identify other individuals (This does not of course mean that they are aware that this is what they are doing).

Dennett says "the process of evolution by natural selection - has no foresight at all, but has gradually built beings with foresight . . . A mind is fundamentally an anticipator, an expectation-generator. It mines the present for clues, . . . turning them into anticipations of the future. And then it acts rationally, on the basis of those hard- won anticipations." But what is different about the kind of mind that a human has?

On the question of what sort of clever behaviours can only occur in the presence of clever thoughts, Dennett proposes as an example the ability to take the intentional stance towards others and towards the self. Nicholas Humphrey (1978) proposed that self-consciousness developed to enable us to think up and test hypotheses about what others are thinking. Dennett argues that it is equally possible that the ability to adopt the intentional stance towards others could be the prerequisite for applying it to oneself.

Dennett argues that a key point in the journey towards human consciousness was the step taken between first and second order intentional systems. A first order intentional system is one that has beliefs and desires about some things, but not about beliefs and desires themselves. A second order system is one that has both. Unthinking natural psychologists do not need to represent the minds of those they interact with. They can operate from an extensive list of alternative behaviours and appropriate reactions. So, Dennett asks, what made it necessary for us to go beyond this strategy?

Dennett recognises that all human minds are shaped not only by natural selection but by enormous cultural influences which effectively redesign our minds. He invites us to think of the conscious mind as consisting of those mental contents that win in competition against other mental contents in the battle for control of behaviour. What we are is the "organisation of all the competitive activity between a host of competences" that our bodies have developed. Consciousness is defined by what a mind can do - whether it can concentrate, be distracted, recall earlier events, keep track of a number of things at once etc. Dennett urges us to resist the temptation to imagine animals as accompanying their clever activities with streams of reflective consciousness as we would. We may not know that they do not, but we certainly cannot assume that they do. He notes that the more we learn about clever activities in animals and how they are accomplished, the less the processes in their brains seem to resemble the thoughts we imagined were doing the work.

Rita Carter, prizewinning author of Mapping the Mind, has her own take on the human mind. She argues that human beings must be determined because we are part of the natural universe which is entirely governed by the laws of cause and effect. She concludes that free will is an illusion; "The reason it is so utterly convincing is that the illusion - like the illusion that the objects around us are solid, or have some integral colour - is deeply wired into the brain as a set of mechanisms which automatically create the sense of self/subjectivity and agency that makes it feel as though we decide what our acts will be rather than merely respond to stimuli." She cites as evidence that this is the case experiments that show that the brain begins an action before consciousness of it emerges. She also argues that neuroscience is now unravelling the mechanism of self and agency and these are charted well enough for them to be copied in AI systems which raises the question; will these "self-sensing" robots develop the same sense of agency and subjectivity we have?

In contrast, Kenan Malik, author of Man, Beast and Zombie argues that human beings are both determined and free because we can be both subject and object; freedom is not the freedom to act arbitrarily or without cause, but is defined by the fact that human activity has reasons motivating it. We have intention and the capacity to act rationally. He claims that our sense of agency and subjectivity is unique and emphasises the importance of language because it "emancipates thinking from the here and now . . . both of our senses and of our culture, and causes it to range freely over the actual, the probable, the possible and even the impossible. It permits debate and criticism, hopes and aspirations, fears and longings." For Malik, because humans are both individual personalities and are truly social, we have the ability to transcend our immediate circumstances. His is a humanist view; he believes that "(t)he development of consciousness, and hence of freedom, requires humans to raise themselves above nature, to control it rather than have nature control them."


C. Badcock., Evolutionary Psychology: A Critical Introduction, Polity Press, Cambridge, 2000
R. Carter, Mapping the Mind, Weidenfeld and Nicolson, 1998
H. Cronin., The Ant and the Peacock, CUP, Cambridge, 1992
C. R. Darwin., On The Origin of Species by Means of Natural Selection, John Murray, London, 1859
C. R. Darwin., The Descent of Man and Selection in Relation to Sex, John Murray, London, 1871
R. Dawkins., The Selfish Gene (new edition), OUP, 1989
D. C. Dennett., Kinds of Minds: Towards an Understanding of Consciousness, Phoenix, London, 1997
R. A. Fisher, The Genetical Theory of Natural Selection, Clarendon Press, Oxford, 1930
K. Malik, Man, Beast and Zombie, Weidenfeld and Nicolson, 2000
G. Miller., The Mating Mind, BCA, 2000
M. Ridley., The Red Queen: Sex and the Evolution of Human Nature, Penguin, 1993 (reissued 2000)

Order these books from Amazon
Evolutionary Psychology: A Critical Introduction Mapping the Mind The Ant and the Peacock The Origin of Species The Descent Of Man The Selfish Gene
Kinds of Minds: Towards an Understanding of Consciousness The Genetical Theory of Natural Selection Man, Beast and Zombie The Mating Mind The Red Queen: Sex and the Evolution of Human Nature

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© C J M Hewett, 2003