Different approaches can tackle this problem. The strategy I personally pursue is to study those creatures who, despite their ability to communicate each other in a complex manner, do not have anything similar to the verbal language: these creatures are the other animals.
What can they do? Are there any limitations (and, if yes, of which kind) to thinking in absence of language?
We know that animals deprived of language can nevertheless perform complex tasks. A good example is offered by the concept of number. Experiments that we have conducted demonstrated that newly born chicks are good at elementary maths. A chick is confined in a transparent cage from which it sees a small ball disappearing behind a panel and four other balls disappearing behind a second panel. If we shift two balls from one panel to the other, once free the chick, which is subjected to the imprinting also in the case of artificial objects like small balls, will go where there are more balls. The chick will behave this way also after repeated experiments where a different number of balls is moved from one panel to the other. This proves that there are animals capable of memorising and conducting simple mathematical operations on objects, despite these animals have neither linguistic capacities nor words to name numbers.
Another example regards the use of tools. Not only humans create and use them. The New Caledonian crow constructs small spears and hooks with leaves and twigs in order to catch grubs in the holes of trees. Some crows, taken into the laboratory and equipped with a straight piece of iron wire, are capable of building up a hook thanks to which they can lift a bucket full of worms. No great ape does it, and even in the evolution of the human species this capacity appeared relatively recently.
If our “being special” in counting up and using tools is a question of degree, what does the language faculty offer to us which the other species lack?
It is recommendable to start thinking the other way around, that is the possibility that language and words have taken away something from us. It might be the case that the brain is a sort of “game at sum zero”: because the number of neurons is limited, if the brain is used to develop certain capabilities, maybe it is limited in the development of other capacities.
An example for showing this point regards numbers, again. A Japanese scientist has trained a chimp to press a series of numbers in sequence on a calculator screen. The animal is able to perform the task without difficulties. It does not seem to have problems, not even when, after pressing the first number, some covers mask the others. The chimp can remember the position of numbers relying on his short-term memory. In humans only few babies present a similar capability which, however, disappears with the learning of language. Perhaps the possibility to carry out this task like the chimp is the price to pay for having words.
In what ways, then, does language render us special? Like us, chickens, pigeons and fishes too seem to be able to solve the so called “transitive inference” tests (if A is taller than B, and B is taller than C, then A is taller than C), maybe because these logical competencies are important in social contexts. If in a chicken run an unknown individual shows up, who prevails on the strongest member, the weak members will not confront themselves with the new comer, because they immediately deduce their inferiority. This is certainly the reason why animals, and not chickens only, have these complex logical skills: because these skills are important in a social context.
In my opinion, what renders human beings special is not the capacity to solve problems, but the capacity of communicating what we have thought to others. This is what language is for.
One day a new comer arrives in the tribe and I see the same things that the chicken saw too, but I do not want to keep these observations for me only, rather I want to tell my relative or my friend not to fight with the new comer since the he/she has beaten the tribe chief.
Language offers us the possibility to socially share knowledge making explicit processes of thought in order to communicate them to others and playing an enormous difference in the evolution of our species. Many instruments that surround us such as books, schools and libraries would not be possible without language.
This is what language gave us perhaps at the price of something stolen from us.
Giorgio Vallortigara is professor of Neuroscience and Animal Cognition in the Faculty of Cognitive Sciences. He directs the Laboratory of Animal Cognition and Neuroscience Center in the Interdepartmental Brain Mind Centre, University of Trento. He is an “adjunct professor” at the School of Biological, Biomedical and Molecular Sciences at the University of New England, Australia. He is the author of more than 150 scientific articles and several books on popular character. He is part of the editorial board of international journals “Animal Cognition” and “International Journal of Comparative Psychology”, he is co-editor of the magazine “Laterality”.