Before we can answer the above question it is important to understand what the term ‘theory of mind’ (or TOM as it is generally abbreviated to), means in evolutionary psychology. At its most basic TOM is the ability of one person to understand the mind of another, to imagine ourselves in their shoes as it were. We use this ability to make guesses or predictions as to an individual’s likely reaction when presented with a particular set of circumstances.

We call it a theory because we can never actually connect with another’s mind. There is no objective way to verify the contents of their consciousness or to assess their motivations and desires. Instead, when we interact with other people we can only guess at these things, using our theory of mind to work out what they know, think or feel. Theory of mind is also considered to be, as Nicholas Humphrey the British psychologist argues, a measure of intelligence.

Although there are many different methods of defining normal academic intelligence, He was concerned with a more general definition. In his paper ‘The social function of intellect’, Humphrey saw intelligence as the capability to modify ones actions as a result of a legitimate deduction from the evidence presented. Using this definition he claims that there is ‘low-level’ intelligence defined as ‘… the ability to infer that something is likely to happen merely because similar things have happened in comparable circumstances in the past’ (Ch2 p. 123).

For example goldfish may swim towards the top of their tank when someone approaches them; for they have come to learn that such approach generally signifies feeding time. Humphrey thought that it was this sort of aptitude that was prevalent in the animal kingdom. He also believes that there is high-level intelligence which he defines as ‘the ability to infer that something is likely to happen because it is implied by a novel conjunction of events (Humphrey, 1976). This type of intelligence, he argues is more uncommon and a feature of advanced primates.

Humphrey, reasoned that although low-level intelligence may have been responsible for solving some of our hunter-gatherer forefathers immediate problems, he recognized that because evolution must have adaptive worth, it alone could not be responsible for the evolution of creative or high-level intelligence. Consequently he believes that some sort of problem had occurred which required an adaptive worth to form within instances of high-level intelligence. Otherwise, to follow it to its logical conclusion, society today would still be comprised of hunter gatherer’s.

This sort of ‘reverse engineering’ approach, beginning by asking why human intelligence evolved, then using his existing knowledge of the environment and animal behaviour, led him to reason that whilst all animals may encounter problems of a recurring nature, the solution of which requires some intelligence, only the higher primates had the higher-level intelligence required to solve unique problems. But what was this problem that led to the existence of high-level or creative intelligence? Humphrey concluded that this problem was social in nature.

He reasoned that it was in a hunter-gatherer’s best interests to be a part of a society where mutual knowledge and differing skills could be shared. Of course a society is comprised of other individuals each with his/her own agenda, hence, whilst it might be beneficial to be a part of a society other benefits might also be drawn from an individuals ability to take advantage of other members. On this assumption he further reasoned that this society would require an amount of reasoning in the individual member, an ability to cooperate or compete, and to cognitively consider which is more beneficial.

Also, this consideration must give some weight to the likely reactions of the other members. For example, will a particular set of actions initiate a hostile or a favourable response? And from that to decide if the profit or loss any action initiates is worthwhile. This chain of thought could be further complicated by the fluid nature of the behaviour of others, for example what might be acceptable now may not be tomorrow and vice-versa.

This type of reasoning skill would require high-level or creative intelligence and Humphrey argued that this type of intelligence provided the answer to the problem of maintaining a cohesive society. Is it just theory of mind that sets man apart from other higher primates then, most notably monkeys and apes who demonstrate similar abilities, Or some other factor? To answer that we need to accept firstly that high-level intellect develops as a result of social skills developed from living within a society.

And secondly, those cognitive abilities are enhanced by an individual’s ability for memory and learning. In fact only apes seem to possess these two factors and Byrne co-author of ‘Machiavellian Intelligence: Social Expertise and the Evolution of Intellect in Monkeys, Apes and Humans’ (1988), says that only by considering these two factors can we reach some understanding of why there are significant differences between monkeys and apes. Byrne further supports his argument by citing the ape’s unique usage of tools and its imitative qualities.

Accepting that this as a valid argument we can understand why humans and apes differ from other simians, and why from these factors we can find the beginning of human intelligence. So what sets humans apart from apes? Andrew Whitten (Byrne’s co-author) writing in 1999, suggests the determining factor is our ancestors move from the forests to a savannah like environment, for here hunting brought entirely new problems, such as big cats, that not only sought the same prey as hunter-gatherers, but considered the hunter-gatherers as prey to.

Whiten, in response to observation of the Kung San tribes (who were one of the last tribes of hunter-gatherers) hunting behaviour by Lee, (1979) (In which Lee describes how hunting can be a highly cognitive process), argues that such behaviour taking place within a social environment cultivates cognitive abilities in tandem with social skills with each refining the other. This interdependent combination of skills evolved to solve many of the practical problems faced by the new environment of the savannah, whilst having the added benefit of further development of the society’s social skills.