Cognitive abilities — the result of selective pressures on food acquisition?

Abstract

Locating and capturing food are suggested as significant selection pressures for the evolution of various cognitive abilities in mammals and birds. The hypothesis is proposed that aspects of food procuring behaviour should be strongly indicative of particular cognitive abilities.

Experimental data concerning higher mental abilities in mammals and birds are reviewed. These data deal with self-recognition studies, rule-learning experiments, number concept, deceptive abilities, tool-use and observational learning.

A Darwinian approach reveals: (1) the adaptiveness of particular abilities for particular niches, (2) that in complex foraging environments, increases in foraging efficiencies in animals should result from the evolution of particular cognitive abilities, (3) that phenomena such as convergent mental evolution should be expected to have taken place across taxonomic groups for species exploiting similar niches, (4) that divergence in mental ability should also have taken place where related species have exploited dissimilar niches.

Experimental data of higher mental abilities in animals concur with a Darwinian explanation for the distribution of these cognitive abilities and no anomalies have been found.

There are, as a consequence, significant implications for the welfare of animals subject to training when training methodology gives little or no consideration to the various mental abilities of species.

Introduction

Comparing and contrasting ‘intelligence’ in humans and animals has long been a preoccupation in our species, frequently within a very anthropocentric framework. Romanes, for example, believed that parrots knew what they were talking about, that rooks had a sense of justice and that dogs enjoyed a good joke. Darwin himself attributed human feelings to animals such as a sense of duty, shame, knowing right and wrong and opined that ants could have sentiments of despair (Sparks, 1982).

In the 20th century, the demise of behaviourism and the broader acceptance of cognitive psychology were an inevitable response to the rigidity of behaviourist principles, coupled with the growing appreciation of the complexities of animal behaviour. However, subjective mental experiences are still not attributed to animals, and the majority of contemporary ethologists refrain from ascribing terms to animals such as ‘think’, ‘intend’ or ‘believe’ (Griffin, 1992).

Currently, this historical diversity of opinion on cognitive capabilities in animals is still evident. This diversity is reflected in the range of opinion spanning two opposing viewpoints held by: (1) those who believe that what we mostly accept as evidence of conscious intent can be more parsimoniously explained by hard-wired abilities and conditioning; ranging to, (2) those who believe that we underestimate the mental capabilities of animals.

The former point of view is held by researchers such as Carruthers (1989) who speculates that it may be “all darkness in the animal mind”. Similarly, Ingold (1988) rules out any conscious intent in animal behaviour. Bermond (1997) argues from the point of view of anatomy, that because the higher-order functions of the prefrontal cortex and right neocortex are known in humans, then we should also be able to argue conversely that those animals without such structures should be incapable of such higher mental abilities. He points out that the prefrontal cortex is well developed only in the great apes and humans and that some parts of the human frontal lobe are uniquely human. Bermond refers to the work of Plutchik (1994) explaining that there is no evidence for an “Aha experience-type intelligence”, long-term planning or self-consciousness in animals other than the great apes and possibly dolphins.

On the other hand, the emerging picture of complexity of the animal mind supports the viewpoint which contends that we underestimate mental ability in animals. Indeed, it is the diversity of those species which appear to exhibit higher mental abilities (such as the great apes, the toothed whales and some birds) which provides reasonable grounds on which to speculate about the ubiquity of such abilities within animals in general. For example, Dawkins (1993) extends her list of animals which make conscious decisions to include deer and grouse. She describes the “roaring matches” between red deer stags, dismissing the previously held notion that these were simply threat displays. Instead she argues that the stags were trying to “work out” which one were likely to win a fight beforehand and that the stags had a “crude idea” of which was likely to win. Similarly, Griffin (1992) believes that communicative gestures in animals convey conscious thoughts and subjective feelings from one animal to another. This, he claims is objective, verifiable evidence of the mental experiences of the animals themselves. Griffin also considers that versatile adaptability to novel situations is also powerful evidence of conscious thinking in animals. Even anthropomorphism is sometimes defended as legitimate within certain contexts, in that animals might, in fact be able to think about certain things that are important to them (Fisher, 1990).

Dennett (1996) however, cautions us concerning our assuming without proof that animals have insight into their instinctive behaviours. To do so “is to ignore the null hypothesis in an unacceptable way — if we are asking a scientific question”. In any serious examination of animal mental ability, the importance of Dennett’s proposition can not be underestimated.

It should follow that an understanding of an animal’s mental abilities is important in the management and training of domestic and zoo species and thus, has welfare implications. For example, an animal’s mental ability will determine, to some extent at least, its ability to suffer when deprived of certain stimuli (Nicol, 1996). Furthermore, a more exact understanding of the mental abilities of animals must be beneficial in terms of their husbandry and training. In particular, when humans have expectations that animals ‘understand’ what is required, they are likely to give inappropriate signals to the animals, such as delayed, inconsistent or meaningless reinforcements, resulting in deleterious behavioural changes. These changes are manifest in conflict behaviours such as redirected, ambivalent and displacement behaviours, stereotypies and injurious behaviours (Wiepkema, 1987). Houpt (1979) has identified learned helplessness in domestic horses.

Ödberg and Bouisseau (1997) revealed that in a study of 2970 horses sent to a Munich slaughterhouse, between 25 and 50% were there for behavioural reasons and most were less than 3 years of age. There is no reason to suspect that the situation would be different elsewhere, or that other trained domestic species would be less at risk from training failures.