There's a cover story in the April 2016 issue of Scientific American that raises again the very interesting question about what drove (and drives) the evolution of human intelligence. As the piece points out, about 70 years ago it was a given that only humans make tools and tool-making defines us. Now, sixty years after Goodall observed chimpanzees making them, it is a given that all kinds of animals -- and plants -- make and use tools of all sorts, from fashioning spears out of the right sort of twig to cooperating with other life forms for offense, defense and signalling. One of the leading exponents of the notion that social complexity drives the evolution of intelligence is Frans de Waal a professor at Emory University in the US. De Waal is famous for describing chimpanzee social behavior as Machiavellian. I have written about him and his work in SMARTS. The Scientific American story is by another group at Emory which has circled back to where this argument began.
These anthropologists, led by Dietrich Stout, study how the complex art of stone tool-making shapes the human brain. Their hypothesis is that the tripling of human brain size since the time of Lucy was caused at least in part by the difficulty of making good stone tools, which required the development of very fine motor skills and even language in order to pass those vital skills on. Step by step, debitage pile by debitage pile, brains got bigger to accommodate discovering and sharing how to knock off just the right bit of stone from exactly the right spot. This interactive process reshaped brain matter and organization: in other words, the shaping of tools reshaped the instrument of thought. The group at Emory has been using neuro-imaging techniques to follow what happens in students' brains as they learn to make stone tools. There is a lovely picture on the magazine's cover of a really beautiful stone spear point with a kind of shadow down the middle. The image suggests the convolutions and hemispheres of the human brain to imply that rock shaping re-made it.
Those who are fascinated by the evolution of ideas in anthropology will read this image in a special context. Anthropologists and archaeologists have consistently tried to find single causes for complex human migrations, cultural shifts, and physical developments. For many generations, they insisted that the first humans to arrive in the Americas must have walked over the Bering Strait land bridge that once connected Siberia to Alaska before it was covered by rising seas at the end of the Ice Age. As they told the story, the first Americans worked their way down from Alaska to the center of the continent and then all the way to South America in about a thousand years, tearing through a pristine landscape populated by giant Ice Age animals naive to how dangerous humans are. With nothing in their hands but wonderfully made stone points affixed to handles that they flung as spears from their atlatls, the first people in the Americas wiped out the big Ice Age mammals. How did anthropologists arrive at this conclusion? Well, some native Americans look similar to Asians, but more important, bones of extinct animals were found that had been penetrated by beautiful stone spear points. These bones were dated to about 12,000 years ago. The spear points, and the culture they represented, were named Clovis, after the town of Clovis, New Mexico where they were first discovered. Clovis points were soon found elsewhere across the US.
This basic story soon dominated anthropology classes though there was almost no other data to confirm it. You would expect, if the story was correct, that Clovis tools would be found in Siberia: no such finds were made. You would expect that if these people arrived before the end of the Ice Age, that they'd have had a serious problem finding their way south through the thousands of miles of glacier that covered the northern half of North America from east coast to west, and all the way down to New York. An ice free corridor was invented to deal with that issue, though no one bothered to search for evidence of same for about fifty years more, and when they did, the corridor notion was disproved. Facts interfered with a nice, simple story that is still taught in anthropology classes even now. That a few ice age animals were killed by humans proved that all ice age animals were killed by humans. It took something on the order of sixty years to get important archaeologists to look at new evidence and reconsider. I wrote a book about that called Bones: Discovering the First Americans.
Back to the folks at Emory. There is something very important about the idea that the brain is shaped by interactions with the world and that this shape is passed down not simply by means of DNA from parents to children, but also by epigenetic means, the chemical record of the specific experience of a particular person which rearranges that person's brain. This sort of plasticity has been well established by neurologists over the last twenty years. The Emory folks have discovered, apparently, that brain areas at work while learning to chip stone tools include Broca's Area, the section originally tagged as responsible for human language, now expanded to include roles in gesture and fine motor skills. However, there is nothing to indicate that stone tool making is responsible for the evolution of Broca's Area, nor could neuro-imaging ever demonstrate such a theory. So once again, anthropologists are walking down the road toward a single explanation, when they should be keeping their minds alive to complexity.
And that brings me to robots. The robots coming soon to your home, your department store, to doctors' offices and operating rooms, will be doing very complex tasks, very precise tasks. They will not be programmed to do these things, they will be set up to learn to do things and to do them better as time goes by. As they learn to do things for us, we will cease to learn to do them for ourselves because we will no longer need that knowledge. Once upon a time, teaching children how to shape stone tools was a vital skill for any human community. When was the last time anyone bothered to teach stone tool making to their child? So here is a question to consider. What happens to our fine motor skills when we no longer have to call upon them for tasks that matter, when we have wired homes and handy robots to take care of these things?
How will that reshape us?
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