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Decoding the Mystery of Consciousness – From Hominids To Humans

Decoding the Mystery of Consciousness – From Hominids To Humans

The skull of the ‘Peking Man’, a fossil specimen of Homo erectus from 750,000 years ago, at the Paleozoological Museum of China. Photo: Yan Li/Wikimedia Commons, CC BY-SA 3.0.

It was a rare epiphany for Jane Goodall when her dearest chimpanzee, David Greybeard, walking along holding her fingers to the Tanzanian deep woods, did the most unexpected. He dropped the banana that she had offered him, looked into her eyes and clutched her hand tightly. It was David’s way of expressing love for Jane, telling her, “I don’t need anything, I am with you.”

Goodall, the English primatologist and anthropologist, had spent much of her life living with and studying chimpanzees. She realised what David did may have resembled the way Homo erectus, the common ancestors of humans, must have communicated affection, about five million years ago

Many scientists think the human mind evolved in manifold ways. One of them was Vilayanur S. Ramachandran. His famous book, The Tell-Tale Brain: A Neuroscientist’s Quest for What Makes Us Human, aptly illustrated his view of the intricacies of the human brain. He proposed the theory of mirror neurons to explain the emergence of the sense of self. Ramachandran doesn’t doubt the claim that the human brain evolved from those of apes, but he does consider interesting questions about how the progressive complexities came about. He believes there was a long “incubation period” before humans’ latent talent suddenly exploded.

Could this figurative explosion have been motivated by particular environmental changes and/or geological events?

The theoretical neurophysiologist William Calvin, who calls the human brain a “Darwinian machine”, has argued that environmental crises drove the enormous increase in human brain size and complexity. The quaternary ice age that occurred 2.6 million years ago and the extreme cold conditions that followed created a crisis of survival for many species. Those that could adapt to their new environment found many opportunities could survive, and even thrive. And the fossil record confirms that the size of the brains of hominids increased in this period.

In cold and dry weather, sans much rain, forests disappeared in many places. In response, the apes are thought to have descended from trees, onto a life on the ground, and transitioned from being herbivorous to carnivorous.

Similarly, fast-running animals are thought to have proliferated as a result of expanding grasslands — just as the hominids had to develop intelligent strategies to hunt in this competitive environment. And it was out of these challenging conditions that a new social order emerged, after the hominids found that hunting in groups was more profitable. In this paradigm, cooperation, friendship, sharing and trust were important.

The historical record indicates that this way of living continued for a long time, but there was yet to be a language to communicate.

Speech is a socially acquired skill and the product of an evolved brain — a cognitive process associated with consciousness. Recent studies have confirmed that chimpanzee lip-smacks confirm primate continuity for speech-rhythm evolution. That is, evolution recycled primate mouth signals as they evolved as sound bites and finally became speech.

The systematic organisation of sound to a language of communication is one of the principal differences between humans and chimpanzees. Research has confirmed that chimpanzees use variations in rhythm to communicate, and the same sound bite when clubbed with different rhythms can convey different meanings. However, they are not capable of packaging the sound bites as words and string them together in the form of sentences.

In his book The Origins of Humankind (1981), the paleoanthropologist Richard Leakey meticulously describes the transformation of the early ape-men of the African savannah to humans. Leakey starts by introducing a heretical notion of how apes started to walk upright. This one step, according to Leakey, birthed the momentum for other evolutionary refinements that eventually set the humans apart.

Bipedalism is a distinctive trait that separated the first hominids from the rest of the four-legged apes. Evolutionary biologists believe it developed as a survival skill. As forests shrank in response to climatic changes, the hominids found themselves descending from the trees to walk on ground. Anthropologists have argued that in the open savannah, resources were scarce and competition high, so the most efficient way to survive here was to stand up, grab something with one’s hands and carry it home.

Leakey also explores how art, language and human consciousness developed together, as well as how the hominids used observations of their surroundings, reasoning and foresight to maintain an advantage over other species.

But why do humans alone among land animals have a consciousness? The English neuropsychologist Nicholas Humphrey defines consciousness as “a cognitive faculty, evolved by natural selection, designed to help us make sense of ourselves and our surroundings”. Intimate studies of chimpanzees have shown that they also show some primary evidence of some sort of reflective consciousness, with the mirror test as proof.

Leakey also describes a different experiment that demonstrates chimpanzees’ ability to think and to react to the thoughts of their peers. Researchers placed a case of fruits in a room and a lone chimpanzee was left there. Later, a second chimpanzee was admitted to the room. As soon as the second one entered, the first chimp closed the open box and pretended to be moving away from it. But when he thought the second chimp was moving away, he returned to the box to take a fruit and closed it. However, the second one was only pretending to leave; he was really hiding and watching!

Evolutionary biologists believe that large jumps in intelligence occur as higher orders of species evolve. This process, called encephalisation, is manifested among other ways by the relative size of the brain, and involves shifts of function from non-cortical parts of the brain to the cortex. The brain of early mammals that originated 230 million years ago was four- to five-times larger than that of the reptiles that had evolved much earlier. Then, the brain size of mammals is thought to have increased about 50 million years ago.

Today, the primates have some of the largest brains among animals, and among them the human brain is three-times as large as that of the chimpanzees.

As the human brain itself became bigger, its internal structure also underwent changes. For example, the cerebral cortex, which plays a key role in memory, attention, awareness and thought, is made up of twice as many cells in humans as the same region is in chimpanzees. Researchers believe that the increase in brain size was mostly gradual, devoid of sudden jumps.

The fossil evidence shows that 6-2 million years ago, early humans began to walk upright and started to make simple tools. In this period, the brain size increased — but only slightly. From 2 million to 800,000 years ago, early humans spread around the world, encountering various environments on different continents.

These challenges, along with an increase in body size, led to larger brain sizes. Indeed, there was a rapid increase in brain size some 800,000-200,000 years ago, credited to a time of dramatic climate change. Bigger brains helped our human ancestors survive in an increasingly unpredictable environment, and enabled them to interact with each other and with their surroundings in new and imaginative ways.

Human and non-human intelligence, from what we’ve observed to date, differ in their ability to develop complex, abstract, internally coherent systems of ideas. The human brain’s unique feats include the invention of new tools, the ability to combine concepts and ideas, and adapting them to new contexts, and the ability to generate and understand analogies. Yet others include the capacity for cooperative problem-solving and communicating about the past and future. These abilities, taken together, lead to greater resilience as a species.

The challenges originating from such situations must have been largely responsible for the development of what we understand as imaginative intelligence. In the parlance of modern management, this concept represents the structure and organisation of a system defined by a prevalent culture, information flows, environment and diversity, all contributing to the functional vibrancy of social groups. It must have meant the same for the primitive hominid societies, except that their communication systems must have been rather crude.

Alliances among the primates can be complicated. Just as it happens in contemporary politics, leadership and roles may change if the situation demands it. Those who have better inner vision can survive better because they are equipped with deeper perceptions. In fact, the expansive functions of the cerebral cortex that develop in primates that live in large communities are not accidental but a larger consequence of evolution.

The fear of death, which finally became the basis for mythology and religion in evolved human societies, must also have contributed to the sense of self and consciousness. However, death doesn’t turn out to be a cause for deep sorrow among chimpanzees. While a mother chimp may walk around with the corpse of her baby in bewilderment, we only wonder what goes on in her mind. Is it the thought of her own death that disturbs her or the numbness arising from losing an offspring?

Neanderthals, a group of archaic humans who emerged at least 200,000 years ago, are believed to have performed rituals for the dead. According to Leakey, “Ritual disposal of the dead speaks clearly of an awareness of death, and thus an awareness of self.”

It was with the arrival of the Homo species that the size and functions of the brain became more versatile, paralleled by developments in the social order and food habits. The transactional relationships must have helped to understand what is good and what is bad from a societal perspective. The codes of morality that are practiced by today’s societies must also have originated from those primordial definitions of right and wrong.

The Cartesian duality of mind and body is no longer a favourable theory. The mind and the body are considered today to be interdependent entities. The evolutionary perspective gives us a better handle to understand the origin of consciousness and its ensemble of attributes that makes us human. It evolved through a synergy of multiple cognitive skills acquired over geological time as a response to emergent environmental exigencies.

Each of us continues to be a participant of this same inexorable evolutionary process, stretching into a future as far as our minds can reach.

C.P. Rajendran is an adjunct professor at the National Institute of Advanced Studies, Bengaluru.

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