Tonight, Steven Mithen, a senior lecturer at Reading University, tells a Darwin seminar at the London School of Economics what he thinks happened to our mental development between 100,000 and 30,000 years ago. That is when the big bang of human culture took place - when art and religion began to flower and when we became a whole lot more intelligent.
It is when the walls separating the different parts of our brains began to come down, when we became able to combine knowledge about the habits of the animals which we were trying to catch with, for example, the design of a hunting tool; when we began to see that bone was not simply the remains of the carcass we had just eaten but a material which could be used to fashion weapons.
In his new book, The Prehistory of the Mind, Dr Mithen likens the mind to a Romanesque cathedral. Before the big bang the intelligence that early humans used for making stone tools or for understanding animal behaviour was trapped in different chapels. The bits of the mind devoted to different domains of behaviour were isolated from one another. After the big bang, light flooded in. We were able to integrate what we knew. That meant our tools were more complicated and effective; we began to conceive art and we began to imagine mythical beings.
But we need to go back further to understand the evolution of the human mind. Six million years ago we shared an ancestor with the chimpanzee. What happened in those 6 million years that led us to be so different? The answer lies in the fossil evidence and the tools early humans used for hunting and gathering. "We have a big challenge because the archaeological record is just constituted of stone tools, their camp sites and animals' bones," says Dr Mithen. "We have to find ways of interpreting those remains to tell us something about their minds. So this new field has evolved which we refer to as cognitive archaeology."
During most of those 6 million years, humans were living by hunting and gathering. Indeed, many people would argue that we are still mentally adapted to a hunter-gatherer lifestyle, that is, living in small social groups. Neanderthal man had a limited cultural repertoire - no art, no religion, no burial rituals, simple technology, crude weapons.
"Between 100,000 and 30,000 years ago there was a dramatic cultural change," says Dr Mithen. "We get the sudden appearance of art, belief in supernatural beings, major technological changes and the start of the technological innovation that's still going on today.
"My argument is that something fundamental happened to the mind at that time. We can think of the Neanderthal mind as having not a single intelligence but separate, modular intelligences, and that fits neatly with arguments coming from psychology at the moment as to how minds really are constructed and how they could have evolved."
Neanderthals made some very good tools but used them simply as thrusting spears. They had immense technical skills but couldn't put those skills to good use by applying creative thought or innovation in the way we would have done. It was not as if they had no reason to change. They were living in harsh environments. Europe during the last Ice Age was no picnic. Bears, wolves and lions were roaming the continent. Almost every Neanderthal skeleton carries the scars of physical injuries or degenerative disease. Hardly any survived beyond the age of 40. In short, they were under very severe adaptive stress.
"If you imagine any modern human under stress like that, we would really start innovating, developing new tools, new ways of living, and we can see that modern hunter-gatherers after 30,000 years ago do that," argues Dr Mithen. "But Neanderthals really had a different kind of mind to what we have today."
Their minds had technical intelligence divided from social intelligence, knowledge of natural history and language. The modern mind is epitomised by our ability to make connections - in our use of metaphor, for example. Take the way science is communicated to the general public. The use of metaphor is critical. Richard Dawkins doesn't simply talk about climbing mountains and selfish genes as ways to help sell his books. He uses them to explain the reasons for evolution. If we didn't think about these metaphors, it would be much harder to think about the ideas at all. The classic case is the way we think about the mind. We need imagery. We talk about the mind being like a cathedral or a computer.
We have, of course, evolved from archaic Homo sapiens. But archaic Homo sapiens and Homo erectus were similar to poor old Neanderthal man. It was Homo sapiens, however, whose mind adapted to have the cognitive fluidity of the modern mind and who spread out around the European continent to replace Neanderthal man. In Europe the first manifestations were in the French cave paintings, which were technically brilliant and brimming with emotion and expression. There was no gradual emergence of such art. It was all there from the start. How can that be? The message must be that the cognitive abilities for art were all present in the human mind, but isolated from one another.
The change in the mind which enabled the art suddenly to be put on paper, or rather on cave walls, was adaptive. It helped early humans to survive in the harsh glacial conditions. "The art is a bit like the CD-Rom today," says Dr Mithen. "It's full of information. It's used for story-telling, it's used for passing on hunting information. It's the key to memory. People are suddenly using material culture for transmitting, recording and storing information."
The modern humans also made all sorts of new hunting weapons using bone and antler. Bone points are more durable than flint points because they don't break and snap as frequently, and they can be sharpened as well as honed easily into differing widths and heights. In addition, modern man made weapons for hunting different animals in specific sorts of circumstances. And they were much better at predicting animal movements, and laying plans to ambush and kill wildlife.
Originally we used language for social reasons, Dr Mithen thinks. We gossiped, just as we do today. But Neanderthal man probably didn't talk about riveting matters such as stone tools and hunting. The changes in the mind really began to happen when the use of language began to change. Language evolved from gossip to being the vehicle for thought. We continued to gossip but we also began to talk about abstract ideas.
Dr Mithen likens British universities to Neanderthal man. Academe is divided into faculties and disciplines, rather like our minds before we suddenly became more intelligent. But in order to understand more about the evolution of the mind we need to break down barriers between archaeology, psychology, philosophy and linguistics. At Reading Dr Mithen is trying to do his bit to break down barriers by setting up a master's course in cognitive evolution across the four disciplines.
'The Prehistory of the Mind' by Steven Mithen, published by Thames and Hudson, price pounds 16.95.Reuse content