You talk when you cease to be at peace with your thoughts.

(Kahlil Gibran, The Prophet)

Many people believe that animals can think and that is true. Now, however, there are some questions. Do animals think like humans? Then, what do they think, and how do we know what they think? If we want to have an idea of how animals can think, we must, however, refer exclusively to an animal, so not to everyone, namely the common chimpanzees (Pan troglodytes). Why only them? The answer, however far-fetched it may seem, is simple. Because common chimpanzees, obviously not all of them, can communicate their thought, with sign language. All the other animals are not capable, or almost. A few attempts were made with the gorillas, but the result was very poor, with others, they failed. Chimpanzees can acquire, even rudimentary, sign language, the same as the deaf-mute, with the same rules as articulated language. Children can do that, but also deaf-mute adults, with the same syntax and grammar as the spoken language in which you make sounds, the phonemes, which are the words that make up the sentences themselves. Basically, what distinguishes us from animals is this second form of language, nothing else. There is no other psychological function that can distinguish man from the rest of the animal world. There are truly surprising cultural, social, cooperative, mental, sexual, even moral affinities between us and them. However, it is not that we want to talk about articulated language here, but about animal thought.


It is on the principle of affinity between us and the chimpanzees that we must start and how animal thought manifests and externalizes itself. Without being aware of yourself and others, therefore without thought, no social cooperation and sexual relationship are possible, let alone morals. These animals, in addition to making a mental representation of themselves, must deal with others, otherwise they would not understand the consequences of their actions and this would be very serious.


Many believe that thought is governed primarily by articulated language and, since animals do not speak, believe that they are also foreclosed on thought, without reflecting on the fact that the word is only an external expression of thought and that, in the course of our short evolutionary journey, its nature has never been changed by the word. Essentially, thought is something else.

Thought is the ability to construct mental representations without the help of a particular reference, for example, sensory or other. The fact is that only one reality is reflected in thought in a different way than reality is reflected in a sensation. In fact, with thought we can make autonomous representations of a problem, of a situation, and thought is never made up of isolated words as in language. Thought is a whole that is more complex than words. In essence, thought is not realized with words but with itself. Even Kant and Hegel were convinced that thought depended on language and that linguistic ability was linked to concepts acquired through experience. They were convinced that language was built through thought. This is not so. Even grammar is independent of thought, as Noam Chomsky1 would rightly say later, adding that chimpanzees could speak independently as children do if they had the proper tools to do so. In essence, thought never coincides with speech. They are separate and distinct phenomena.

In the child, up to about two years of age, the lines of development of thought and language are separated, then, after this age, begin to intersect and from that moment language begins to become intellectual and the thought deductive, verbal and abstract. Language and thought (and here is the fundamental point) have different genetic sources, as Lev Vygotskij2 had well understood at the beginning of the 20th century when he wrote: "Thought and word are not bound together by an original bond. It is realized in the course of the development of the child's thought and word". In this respect, beautiful is a metaphor written by Vygotskij in which he compares thought to a cloud that at a certain point spills a rain, not of water, but of words.

Moreover, thought cannot even be broken down, as the first psychologists of the 20th century tried to do, because in doing so it would lose its fundamental and unitary properties. Thought is global and irreducible and is a property of our brain. Then, if it corresponds to a nervous excitement, that is, to a neural state, maybe animals, especially chimpanzees, but also other mammals, do not have a brain capable of activating a thought like us? We must therefore assume that if thought, as a neural process, can take place in a human brain, it can also take place in that of an animal. It would be the same mental event, not two distinct properties of the brain.

Because chimpanzees can think without the use of articulate language

It can therefore be assumed that animals think like us human beings, but the point is that you must prove it and the only way to do so is to "talk" to them.

First, however, we must ask ourselves some fundamental questions, that is:
- Do the animals have a visual system similar to ours?
- Do they have imagination?
- Do they feel emotions?
- Do they have purposes?
- Are they capable of productive thought, for example, can they capture new properties from the elements of a problem by giving them tools to solve it?
- Do they have social thought (which, by the way, is the first form of thought)?
- Do they have a consciousness?
- In essence, are they psychologically like us human beings?

Chimpanzees have shown experimentally that they possess all these qualities even though their actions are independent of the articulated language that they obviously do not possess. A chimpanzee can have an idea of a banana even without possessing the relative word, that is " banana", said or read (prelinguistic thought).

Wolfgang Köhler3 has noted in chimpanzees the early stages of development of chimpanzee thought in solving problems such as the circumvention of obstacles to achieve a prize and in the use and construction of tools to achieve it without the use of any language, not even that of signs, which chimpanzees can however acquire, although not everyone can do so. Only the most endowed with intellect and cognition can do it. Then chimpanzees are able to emulate, not just imitate, which would be a purely mechanical gesture. Once they learn a new behaviour such as crushing nuts that cannot be opened differently, with stones or sticks, they always try to improve their actions in a way that is more in keeping with their dexterity and even personality. All these operations are independent of the intellectual operations that we human beings do with articulated language, when for example someone instructs us with words, how to solve a problem or how to build a tool that we have never built before. These operations of chimpanzees are done through productive (non-reproductive) thought, the thinking that leads them to identify in the objects that are given to them (for example, separate sticks that can be joined through a groove) something new, that did not exist before, that is, a longer stick to reach a prize that could not be reached with only one stick at a time.

Basically, in these operations the chimpanzees have shown that they know how to reset the problem given to them in new terms and to do so, they did not need articulated language or someone to tell them how to do it. In some tests some chimpanzees were able to recognize objects they had previously only touched without seeing them (that's why at the beginning of this paragraph we wondered if chimpanzees had a visual system similar to ours), having been blindfolded for the test. Female monkeys do even more complex operations than these, for example, they are able to avoid, through deception, the control over their sexual activities by the dominant males.

Sign language

In the 1920s, Robert Yerkes, an American primatologist and psychiatrist, intuited that sign language could be taught to chimpanzees. It is a visual and movement language of the hands. In fact, the language of the deaf-mutes is fundamentally based on movement, even that of reading the movement of the lips as some deaf people manage to do.

We have always given little importance to the movement of the body, but it is also fundamental for the cognitive development and thought of everyone. Nutrition requires movement, for example, the search for food, even breathing is coordinated muscle movement, not to mention reproduction. All these movements are under the control of our brain and cerebellum. In essence, it is not in sound, but in the use of the sign, that is, in movement, the correspondence with the articulated language of man. There is therefore a much closer link between sign and thought than there is between word and thought. The sign always precedes the word, that is, sound, not the opposite.

As humans, through words, we can know everything, (frequency and intensity, etc.), but of thought we know nothing, because at a frequency and intensity of a neural activity of our cortex, we do not know what exactly it corresponds to, we cannot connect this activity to a thought because thought is a property of the brain, it is not the brain.

In conclusion, the word enters into the structure of things and acquires a functional meaning, just as the stick enters into the structure of the situation in which a chimpanzee has to extract termites from a termite mound, or which communicates with sign language.

So how come parrots that talk do not need any sign language to communicate, yet they emit words? The answer is that if speaking parrots had the intelligence of a chimpanzee, they too would be endowed with speech, like human beings, but that is not the case.

In conclusion, it is essential to know the ape part that is in us from the chimpanzees, but also from other monkey species, for the purpose of our awareness of who we are, why we behave in a certain way, rather than another.

1 Noam Chomsky. 1986. Knowledge of language: Its nature, origin, and use. Prager, New York.
2 Lev Vygotskij. 1986. Thought and language. The MIT Press, Cambridge, MA.
3 Wolfgang Köhler. 1925. The mentality of apes. Kegan, Trench & Trubner, London.