The Brain Science Behind Our Obsession With Tools
http://www.popularmechanics.com/science/health/nueroscience/the-brain-science-behind-our-obsession-with-tools-15549633
By Kiona Smith-Strickland
June 3, 2013
According to researchers at Princeton, your obsession with tools
may be the product of millions of years of evolution.
By Kiona Smith-Strickland
June 3, 2013
According to researchers at Princeton, your obsession with tools
may be the product of millions of years of evolution.
Animals as diverse as crows and chimpanzees create and use simple tools, but it's humans who take tool use to an unprecedented level. Only humans invest significant amounts of time in designing and creating complex tools, and only humans turn them into permanent, valued possessions. According to researchers at Princeton University led by neuroscientist Sabine Kastner, human brains are actually hardwired to love hardware.
Kastner's team compared human brains with monkey brains using functional magnetic resonance imaging (fMRI), which produces an image of changing amounts of blood flow in different areas of the brain. When neurons activate in a given area, blood flow to that area also increases. Viewing images of these changes shows researchers how the brain responds to certain stimuli, such as pictures or words.
The brain handles information about objects mostly in the parietal cortex, found in the back of the brain. There a neural pathway called the ventral system identifies objects and sorts them into categories. This pathway is what lets us recognize that a table is a table, whether we're viewing it from across the room or from directly underneath, and it works the same way in humans and in primates.
Nearby, another neural pathway called the dorsal system deals primarily with information about where objects are and how to reach them. In the brains of the rhesus monkeys used in the Princeton study, that information is very basic, and "its only use is to guide reaching and grasping information," Kastner says. In human brains, however, that pathway carries much more detailed information about objects, and we use that information to interact with things in more complicated ways, such as making and using tools.
In fact, the Princeton study even found new areas in the human parietal cortex that show more activity in response to images of tools than to images of other kinds of objects. "There's no part in the monkey parietal cortex that compares," Kastner says.
Commenting on Kastner's findings, her colleague Melvyn A. Goodale of University of Western Ontario tells PopMech: "What's interesting was that there was more activity for tools than there was for simply graspable objects, so simply showing people a stick wouldn't produce as much activation as showing them a hammer." Goodale says that this may be because we immediately associate hammers with a particular action, but we don't associate such specific uses to nontool objects like sticks.
According to Kastner, even people who can't name tools usually have an immediate grasp of their use. "If you give them a hammer, they know what to do with it," she says. Of course, people's brains develop their responses to tools based on their experiences, and those experiences vary widely. "Obviously, a carpenter will have very different representations from mine," Kastner says.
Despite those differences, the human ability to recognize tools and their purposes is, to some extent, as universal as it is unique. "You see that in 2-year-old children—a ball rolls under a couch, and the child will get some kind of long stick to get that ball back. A tool gets invented. Humans can do that, as strange as it sounds, and most other primates in the world just cannot do that. How we reached that kind of flexibility, that is really something that we know nothing about," Kastner says.
She believes that these uniquely human aspects of the brain have evolved along with human tool use over the past 3.4 million years or so.
Which came first: the use of tools, or these changes in the brain? Researchers may never be certain, as the relationship is essentially a cycle. The constant use of tools, from stone hammers to minicomputers, has shaped human brains in ways that enable even more use of even more sophisticated tools.
Goodale says that natural selection probably drove the development of the dorsal system in ancestral primates, whose brains needed to make rapid calculations to grab moving insects or other prey quickly and accurately.
"Having got that in place, then having all kinds of other, more cognitive parts of the brain evolving in protohumans, then the fact that there was that dorsal system there that could be exploited by tool-using creatures led, I think, to even more specialization of the dorsal system for the use of tools," he says.
Kastner's discovery may be one of the first scientific insights into the evolutionary origins of tool use. "There are very few people that have ever studied tools," Kastner says, "and it's not easy to do."
The evolutionary processes that gave us our affinity for cordless drills is still happening, and at a faster pace than ever now that new gadgets and tools come along at such a fast pace. "I think that we will probably see that the brain can change much faster than we think. I think that in a hundred years from now, people will have different parietal lobes," she says.
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"Programming or Soft-Tool Agents"
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