The mind is a product of the way the brain is organised, how the cells are connected and how they interact with each other. It is an "emergent property" and something much more than just a collection of brain cells.
Like any other organ, the brain (and hence the mind) is subject to evolution by natural selection. Basic patterns of brain development are genetically determined. Thus individuals who have a brain wired in a particular way tend to have certain behaviours which may enhance their chances of survival to breed.
The brain of every animal is organised so that it is well adapted to its place in the ecosystem; that is, adapted to the way it makes a living. For example, the cat is a predator and its brain creates a model of the world which is relevant to its life of catching prey, finding mates and caring for its young. Its world is no larger than the area over which it roams and is very limited in relation to the real world, but it includes all the things a cat needs to know to be a successful cat.
What about Man? What is his role in life? Homo sapiens is a highly social, adaptable mammal which works cooperatively. It shares 98.5% of its DNA with chimpanzees, but while chimps survive in only a few patches of African forest, Homo sapiens dominates the earth. Over the past 6.5 million years, since chimpanzees and man evolved from a common ancestor, our brains have expanded and gradually been rewired so that now we fill a niche in the ecosystem not exploited by any other species. This is the "cognitive niche": the ability to understand the world well enough to figure out ways of manipulating it to outsmart other animals and plants. Stephen Pinker, psychologist and evolutionary neuroscientist, suggests that there were several things which evolved at the same time to support our way of life.
The first is cause and effect intelligence: How do sticks break, how do stones roll, how do things fly through the air? The second is social intelligence: How do I coordinate my behaviour with other people so that we can do things together which cannot be done by one person acting alone? And the third is language, so that we can share our experiences and learn from them. I can inform you how to cook eggs just by telling you; I can give you this knowledge in exchange for some eggs; I can negotiate how many eggs the cooking recipe is worth; and I can gossip about the deal with my friends to make sure I am not being cheated.
Pinker suggests that these three mental attributes probably evolved together, the evolution of one promoting development in another. However, archaeologist Steve Mithen thinks that they evolved side by side, but separately. He suggests that women and children played an important role in our early mental development. Up until around 250,000 years ago, women were key to keeping groups together, social bonding and passing on cultural skills such as tool-making. Thus the evolution of mental attributes in the female line would have been important.
What is certain is that something revolutionary happened between 100,000 and 50,000 years ago. Archaeology shows the sudden appearance of more complex technology. People started living in more difficult environments and in bigger communities. Religious and artistic behaviour emerged.
Mithen believes that the key to this "cultural revolution" is that the three separate ways of thinking began to merge. Possibly language changed. Previously it may have been exclusively social ("Me Tarzan. You Jane"), but it was eventually used to talk about tool-making and animal behaviour. Gradually over time, barriers between the different compartments of thinking broke down, giving rise to the use of metaphor in language ("His poisonous words tortured and destroyed me!"), a theory of mind (...if I were you...if I were a cat), and reflective consciousness.
Why are we the clever ones? Why not the chimpanzees? According to anthropologist Richard Wrangham, part of the answer seems to be the invention of cooking. Big brains require a lot of energy. A human brain consumes about 20% of the total body oxygen consumption. Raw food is hard to digest and requires more energy to chew. For example, gorillas spend the whole day chewing just to get enough nutrition, leaving little time over for other activities. Cooking breaks down fibres and softens food. It also increases the number of available calories.
There is evidence for the use of fire by early man from at least 800,000 years ago. Neanderthals had tools and fire, but for some reason they went extinct. Mithen believes they failed to experience the revolutionary merging of the different sections of their minds. Pinker thinks that they were just a little bit less smart than Homo sapiens. Either way, they lost out to us in competition for the "cognitive niche".
Like cats, we see the world in a way which was formed by our evolutionary past. This field of study, called evolutionary psychology, is currently the focus of much research and discussion. It seeks to explain our limitations and seemingly irrational behaviour.
For example, we have in our brains an intuitive theory of how the physical world works. Sometimes this reflects the real world, sometimes not. Take the following diagram:
The top line looks the shortest, and the bottom the longest, but all three horizontal lines are exactly the same length. Even if you measure them and prove this to yourself, each time you look at the lines they seem to be different lengths. Our intuitive theory is wrong, but it has a value in our daily lives since we often use angles to judge depth and distance.
We are good at solid maths and can visualise two bad apples in a bag of ten, but we are hopeless at understanding probability and statistics. For example: In a group of 23 randomly chosen people, what is the probability that a pair of them will have the same birthday? We know that there are 365 days in a year, so we might expect the probability to be quite low. In fact, it is more than 50% (one in two chance). Our intuition is also bad at science because we tend to notice positive results and ignore negative ones. Likewise, we choose studies which support our beliefs and connect events as cause and effect when they are merely coincidence.
These ways of thinking had value in the past, since an early man inventing a new tool would be more successful if he took shortcuts, based his efforts on past experience and selected methods he thought might work. But in the modern world these patterns of thought encourage us to believe in miracle cures and to blind ourselves to the viewpoints of others. Consider the following imaginary news headlines describing scientific studies: "Eating chocolate prevents cancer", and "Eating chocolate does not prevent cancer." To science, both these studies have equal value, but which story would you be most likely to read?
Our intuitive "theory of mind" also has deep social implications. To quote Pinker:
"The lay-person's intuitive psychology or "theory of mind" is one of the brain's most striking abilities. We do not treat other people as wind-up dolls but think of them being animated by minds: non-physical entities we cannot see or touch but that are as real to us as bodies and objects. Aside from allowing us to predict peoples' behaviour from their beliefs and desires, our theory of mind is tied to our ability to empathise and our conception of life and death. The difference between a dead body and a living one is that a dead body no longer contains the vital force we call a mind. Our theory of mind is the source of the concept of the soul. The ghost in the machine is deeply rooted in our way of thinking about people."
Thus, some of what we deeply believe to be true may be an illusion born of our evolutionary past. Science shows us how to understand this intellectually. However, behaviourally, culturally and in our day to day social interactions we will continue to be governed by the way our human brain and mind have evolved. We cannot help it. It is what makes us human.
by Christine Betterton Jones - BSc. (Zoology), PhD (Parasitology)
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Bibliography:
Steven Pinker: Evolution of the Mind
Mind and Metaphor: Archaeology and the Evolution of Mind - An Interview with Steve Mithen
Evolution by Fire, Harvard Magazine, October 2009
Ben Goldacre, 2008, Bad Science, Harper Collins
