As we look at the fossil evidence for human evolution, one of the striking features in the evolution of human anatomy is the large brain. It is, however, not just the size of the brain that makes us human but, more importantly, the way the brain works. The way the brain works is a reflection of the architecture of the brain, of how the different components of the brain communicate with each other, how information is stored and recalled, and how these things make us perceive and react to the physical world around us.
The human brain is basically an information processing mechanism. The brain receives a constant stream of information from the various senses—sight, hearing, touch—and processes this information to allow human perception of the world. It is then the job of the mind to interpret the information and make sense out of it. In her book The Human Brain, Rita Carter describes it this way:
“The brain receives a constant stream of information as electrical impulses from the neurons in the sense organs. The first thing it does is determine whether the information warrants attention.”
Determining which information needs attention, which needs to be remembered, and which can be discarded (i.e. forgotten) is the task of the mind. What is the mind? In his book The Believing Brain: From Ghosts and Gods to Politics and Conspiracies—How We Construct Beliefs and Reinforce Them as Truths, Michael Shermer writes:
“All experience is mediated by the brain, the mind is what the brain does. There is no such thing as ‘mind’ per se, outside of brain activity. Mind is just a word we use to describe neural activity in the brain. No brain, no mind.”
Part of the processing of sensory information involves memory—both laying down new memories that can be later recalled and accessing memory to determine response to the data.
While it is the large size of the human brain that distinguishes us from other primates, it is actually the mind that make us human. In his book The Gap: The Science of What Separates Us from Other Animals, Thomas Suddendorf writes:
“Consider one of the most fundamental aspects of our human mind: we can imagine things other than what is available to the senses. We can picture past, future, and entirely fictional worlds and think about them.”
In his book In Search of Memory: The Emergence of a New Science of Mind, Eric Kandel writes:
“Understanding the human mind in biological terms has emerged as the central challenge for science in the twenty-first century. We want to understand the biological nature of perception, learning, memory, thought, consciousness, and the limits of free will.”
This raises the question about how we can go about studying the mind. Obviously, we can study the mind indirectly through human actions such as speaking and making tools, but how do we see the mind in biological terms? The clue for this comes from how the brain works. Rita Carter points out:
“The brain works by generating small electrical charges. Functional imaging reveals which areas are most active.”
Brain imaging includes Positron Emission Tomography (PET) scanning and fMRI (Functional Magnetic Resonance Imaging). While anatomical imaging provides information about the structure of the brain, functional scanning allows neuroscientists to see the electrical activity in the brain as people carry out specific tasks. Rita Carter reports:
“This allows them to link types of actions, emotions, and so on, to specific types of activity in the brain. The freedom to observe the brain that imaging techniques have afforded has allowed for an explosion of knowledge within neuroscience, and has deepened our understanding of the brain and how it works.”
Brain imaging, of course, lets neuroscientists view the workings of the brain in modern, living humans. But how do we study the brain, and, more importantly, the mind with regard to human evolution? With the fossil record, paleoanthropologists have been able to document the evolution of human brain size, and, particularly, the evolution of the frontal lobe and the frontal-polar cortex which are involved with forward planning and other aspects of the human mind.
Most of the data on the evolution of the human mind comes from the archaeological record and evidence of complex planning, symbolic behavior (including both language and religion), learning, and memory.
The making of stone tools, for example, can be an example of forward planning. Not all stone produces a cutting edge and therefore requires the stone to be acquired in one area, manufactured into tools in another area, and finally used in still another area. As stone tools become more complex, such as hafting them to wood to make spears, knives, and hammers, even more complex planning is involved.
Learning, and perhaps some symbolism, can be seen as stone tools become stylistic—that is, the ultimate form of the stone tool comes not from the stone itself, but from an a priori image in the maker’s mind. Producing the symmetrical Acheulean handaxes and cleavers which first appeared in Africa between 1.7 and 1.3 million years ago probably required learning beyond simply watching someone else flake one. In an article in Scientific American, Dietrich Stout writes:
“…knappers use a variety of ‘hard’ (stone) and ‘soft’ (antler/bone) hammers as they work through planned flaking sequences that prepare core edges and surfaces to fracture in the desired pattern.”
There are some researchers who feel that teaching this complex pattern of tool-making may have required sophisticated communication, such as language.
With regard to the symbolism of the Acheulean stone tools, Lee Berger with Brett Hilton-Barber, in their book In the Footsteps of Eve: The Mystery of Human Origins, write:
“One perspective is that the Acheulian culture was the first formal expression of rules being introduced into society. These rules had to do with the way stone tools—particularly bifaces—were made and with what they were made.”
Lee Berger with Brett Hilton-Barber also write:
“The patterns cut into bifaces are probably the first use of symbolism, suggesting either the beginnings of a belief system or the first stirrings of an aesthetic sensibility.”
We don’t know exactly when the fully human mind first evolved. There are many scholars who feel that it evolved with the first anatomically modern humans about 200,000 years ago, while there are others who feel that the mind evolved before anatomically modern humans, and there are a few who feel that it did not emerge until as recently as 50,000 years ago.
More About Human Origins
Human Origins: The Large Brain
Human Origins: The Human Hand
Human Origins: Bipedalism
Human Origins: Sexual Selection
Ancient Africa: Australopithecus
Ancient Africa: Homo Naledi
Early Homo Sapiens: A Brief Overview of DNA