Chimp or Human: Just How Different Are We?

By Mark Markov

This question has been at the heart of human investigation for many centuries; the debate extending past any single field – with philosophers, psychologists, anthropologists and evolutionary biologists providing their unique takes on this problem from as early as the 17th century.

When tackling this issue, we cannot merely limit arguments to singular scientific concepts, such as the similarity of genetic material, but must employ a holistic approach. It would be prudent to approach a concept considering the context of both the human and animal brain.

When separating the two sets, one base issue stands out immediately. Language has been the vehicle for human progress, the engine of industry, culture, agriculture and civilization; a power which was biblically capable of rivalling God, who was Himself afraid of the progress mankind made under one language, striking down the Tower of Babel. But it is not a feature unique to hominids. Kathleen Gibson gives evidence that when you undergo comparative neuro-anatomical analysis: there are no qualitative differences between the brains of humans and great apes that seem to allow for the complex linguistics. Although quantitative differences exist, such as several major neural structures such including the neocortex and cerebellum being three times as large in our brains, the behaviours and cognitive processes facilitated by these parts of the brain, previously thought to be uniquely human, are present in those apes.

The average great ape is capable of mental construction and the use of symbolism (mediated by the neocortex) and procedural learning (mediated by the basal ganglia and cerebellum). The latter is the ability to join two or more concepts or perceptions in order to create new info-rich constructs and use those in an embedded chain to form yet higher-level constructs. These are the skills that facilitate the simultaneous movement and coordination of body parts used in gymnastics and dance. They are also the same skills which allow for humans to produce individual speech sounds by changing how our tongue, lips and other vocal instruments move in accordance with different arrangements of the vocal tract. The same concept of mental construction can be applied in art and architecture, as well as the use of tools. However, there are various levels of complexity here. Whilst there is only a bifocal relationship between the hammer and nut in chimpanzee tool-using, there is a much more complicated process, consisting of many more variables, in even the most basic examples of human ingenuity, like the construction and use of the spear.

The argument detailed so far, referred to as the contrasting continuity position, is the same one proposed by revolutionary evolutionary biologist Charles Darwin, who said "mental differences between animals and humans are matters of degree, not of kind."

This idea is rivalled by another, an idea of qualitative uniqueness in the behaviours of hominins in comparison to animals. This is a belief shared and confirmed amongst even those outside the biological community. Famous French philosopher René Descartes encapsulated the argument in the 17th century when he said that animal behaviour is ‘instinctive’ whilst human behaviour is ‘rational’. This is an analysis supported by a common tool used in biology known as Morgan’s Canon, devised by Lloyd Morgan (an English psychologist) which states that one should always assume that animal behaviours are caused by the simplest possible mental faculties.

This is supported in contemporary journals. There are features of hominin cognition that are unique, and are not shared by great apes. Whilst the skeletons of these processes are observable in our primate cousins, they lack the level of complexity we attribute to our own behaviour. For example, whilst great apes are aware of the intents and wants of others they fail to utilise this information and lack communal purpose. On the other hand, cooperation and community can be observed even in human infants. A practical example of this is that whilst when male chimpanzees hunt, they do so cooperatively, yet the spoils go entirely to the successful captor.

Overall, the two arguments, whilst contradictory of each other, both have their merits and are deeply rooted in archaeological evidence, opinions from experts in anthropology, and close neuro-anatomical and behavioural monitoring of subjects. However, our knowledge of the process of evolution, and the evolutionary pressures which lead to rapid neural expansion, are too restricted to predict whether those primitive semblances of hominid cognition will blossom into a state similar to ours.