Intelligence has been considered a unique feature of human beings as it gives us the ability to devise elaborate strategies for solving problems. There are three key evolutionary explanations of intelligence, which are, foraging/ecological, social and sexual selection. Foraging is when animals learn food preferences from others. This ability has clear survival advantages because the animal can learn from others rather than using trial and error process to identify which foods are harmful. The larger the range of food required, the larger the foraging area must be and the greater the requirement for more complex abilities.
Many primates have to balance their diet by selective eating through successful hunting, which requires forethought, planning, cunning and the ability to coordinate the actions of a number of individuals. Finding food over a particular area may require a cognitive map (memorized spatial knowledge).Obtaining the food requires tool use and hunting techniques, which is another indication of intelligence in both human and non-human species. Visalberghi and Trinca (1987) did a study to look at the effects of tool use. Capuchin monkeys were given task of pushing peanut butter out of a tube. They found that the monkeys were quick at finding a suitable stick but tried out many unsuitable ones first. This suggests no understanding of causal relationships and that many animals develop the skill through trial and error rather than insight.
Only the great apes show the sophisticated understanding of cause and effect so this supports the link between tool use and intelligence. The association between the growth of hunting and intelligence shows that more intelligent individuals are more intelligent than less intelligent. However many species with very successful hunting techniques are not very intelligent and therefore it is unlikely that the benefits of hunting would account for human levels of intelligence. The efficiency in foraging of a particular animal has been shown by various psychologists. Galef (1988) did a study in which a rat was allowed to eat food with a distinctive flavour, with cocoa or cinnamon.
A test rat was then put in with the demonstrator for 30 minutes, but with no food present. This test rat then had to choose between cocoa-flavoured and cinnamon-flavoured food. It was found that the test rats preferred food of the same flavour as that eaten by the demonstrator. This was still the case 4 hours after the demonstrator had eaten and when 12 hours had elapsed before the test rat made its choice.
Therefore it can be concluded that interacting with a rat after it has eaten creates a particular preference for that food. These results could be interpreted in a number of ways, in terms of the rats been neophobic, meaning unwilling to try anything new. The test rat could have picked up on the smell of the particular food on the breath of the demonstrator and will have been choosing between what was familiar and unfamiliar rather than been influenced directly by the demonstrator actually eating the food. However despite this Galef also found similar results even when the test rats were familiar with both cocoa and cinnamon flavoured food.
The social theory says that interactions with other members of a social group present an intellectual challenge and primate intelligence has been evolved in response to this challenge. It has been suggested that intelligence is an evolutionary adaptation for solving social problems. The most intelligent species are the social animals, which are bees, parrots, dolphins, elephants, wolves, monkeys, etc. The group living could have set the stage for the evolution of intelligence in two ways; sociality which increases the value of having better information, because information is one commodity that that can be given away and kept at the same time. For example a more intelligent animal within a group has the benefit of knowledge and what it can get in exchange for the knowledge.
Secondly group living itself has new cognitive challenges. Social animals send and receive signals to coordinate predation, defence, and foraging and sexual behaviour. They exchange favours, repay and enforce debts, punish cheaters and join coalitions. Machiavellian Intelligence Hypothesis came from various related hypotheses, which Bryne and Whiten (1988) brought together. This suggests that deceiving and detecting deception are the primary reason for the evolution of intelligence. Evidence supports this, as Bryne and Whiten (1992) have shown that there is a strong positive correlation between neocortex ratio and the prevalence of tactical deception in various primates and this implies that there is a clear relationship between social manipulation and intelligence.