Thought and Language

Recursive thinking, the ability to embed ideas within other ideas is the underpinnings of human communication. Understanding more about how this ability evolved may help us unlock the complex challenges we face today.

All humans are born with the ability to speak and think recursively. But our individual languages are unique, adaptive tools, each one shaped and modified by the environment in which it developed. The language we are born with and the way we write it influences how we perceive time in space and how we remember events.

The symbolic creations of the Upper Paleolithic period that we marvel at on cave walls represented a new ability to express experiences and ideas exterior to oneself in two-dimensional art. This new ability would lead to our complex writing and numerical systems and to the development of the numerous external memory records and cultural products which proliferate in the world today.

Thought, Brain Size, and Physiology—an Evolutionary Feedback Loop

These transformations required an acceleration in brain development which Merlin Donald and others believe can be explained by the brain’s “plasticity”—its potential for functional adaptation. This quality enabled brain development to proceed at a rate far in excess of the relatively slow pace of genetic evolution.

The transition from speech to external symbols may well have caused a feedback loop where developments in language themselves stimulated biological changes, and these changes further changed our biology. A study led by anthropologist John Hawks concluded that in the last 5,000 to 10,000 years, as agriculture was able to support increasingly large societies, the rate of evolutionary change in human genetics was more than 100 times faster than before. And the genes related to brain development were evolving fastest.

Thanks to the work of Sue Savage-Rumbaugh and others, we know that captive apes who have been taught sign language can communicate about past events, future plans and abstract ideas with their trainers, as well as interpret pictures, enjoy humor, and display other human-like mental skills.

Captive gorillas may acquire new modes of thinking in the process of learning sign language, but it’s unlikely that these developed exclusively because of the training. As we have seen, apes gesture intentionally; bonobos and chimps show some degree of future-thinking and mind-reading even in the wild. In these circumstances, thought does precede its expression. The language ability of apes may well be a protolanguage originally shared by our ancestors—a precursor of our own ability.

However, it is more than likely that only humans can remember countless episodes from the past, make numerous plans and continuously predict future situations. As we know from our favorite entertainments and, of course, from gossip, we are particularly interested in the lives of others. We need to communicate.

There is a distinction between what individuals can think about and what they can communicate. The question is how much do these two activities affect each other? Humans are born with the ability to speak. As infants we think and comprehend things about our physical world before we are able to understand specific words, and long before we can pronounce them.

Our brains grew larger as we developed an ability to express thoughts about the past and the future through mimesis, and from this evolved our unique ability for complex recursive thought. Recursion is our ability to embed ideas within ideas. In The Recursive Mind: The Origins of Human Language, Thought, and Civilization, psychologist Michael Corballis says the ability to think recursively is the primary characteristic that distinguishes the human mind from that of other animals.