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April 29, 2009
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Roots of “free will” seen in flies
May 15, 2007
Courtesy Public Library of Science
and World Science staff
Lower animals are often seen as robotic and programmed in their actions and reactions. Insects, with their
blank eyes and stiff little frames, seem to epitomize these dreary qualities. The fruit fly Drosophila
melanogaster (Courtesy NASA)
But scientists studying fruit flies say they have discovered that the little bugs have been slandered: they in fact display considerable spontaneity,
and this may be at the evolutionary root of what we sense as “free will.”
The research could shed light on a centuries-old debate over free will—whether anyone really has
it or whether, instead, mindless movements of atoms in our brains control all
our decisions.
The study appears in the May 16 issue of the research journal PLoS
One.
“Animals and especially insects are usually seen as complex robots which only respond to external stimuli,” said Björn Brembs
of the Free University Berlin, one of the researchers. When scientists see animals responding differently to the same stimuli, they typically
ascribe this “to random errors in a complex brain.”
Using behavior recordings and mathematical analyses, the researchers found that such variability can’t be due to
pure chance but is generated spontaneously and non-randomly by the brain.
The results caught computer scientist and co-investigator Alexander Maye
of the University of Hamburg, Germany by surprise: “I would have never guessed that simple flies who otherwise keep bouncing off the same window have the capacity for nonrandom spontaneity if given the chance.”
The researchers tethered fruit flies, Drosophila melanogaster, in uniform white surroundings and recorded their turning behavior. The flies in this setup receive no visual cues from the environment and since they are fixed in space, their turning attempts have no effect. Thus lacking any input, their behavior should resemble random noise, similar to a radio tuned between stations, the investigators reasoned.
However, the analysis found that fly behavior is very different. Various increasingly complex random computer models failed to adequately account
for fly behavior, the researchers said.
They found the source of the spontaneity, they added, after analyzing the behavior with methods developed by co-authors George Sugihara and Chih-hao Hsieh
of the Scripps Institution of Oceanography at the University of California San Diego.
“We found that there must be an evolved function in the fly brain which leads to spontaneous variations in fly behavior,” Sugihara said. “The results of our analysis indicate a mechanism which might be common to many other animals and could form the biological foundation for what we experience as free will.”
Our subjective notion of “free will” is an oxymoron, Brembs remarked: the term ‘will’ would not apply if our actions were completely random and it would not be ‘free’ if they were entirely determined. So if there is free will, it must be somewhere between chance and necessity—just where fly behavior lies. “The question of whether or not we have free will appears to be posed the wrong way,” said Brembs. “Instead, if we ask ‘how close to free will are we’ one finds that this is precisely where humans and animals differ.”
The next step will be to use genetics to locate and understand the brain circuits responsible for the spontaneous behavior, researchers added. This could lead to the development of robots with the capacity for spontaneous nonrandom behavior,
they said. It may also help, they predicted, in treating disorders leading to compromised spontaneous behavioral variability in humans—such as depression, schizophrenia or obsessive compulsive disorder.
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Lower animals are often seen as robotic and programmed in their actions and reactions to the world. Insects, with their stiff little frames and apathetic eyes, seem to epitomize such qualities. But scientists studying fruit flies say they have discovered that the little bugs have been slandered: they in fact display con siderable spontaneity, which may be the evolution ary root of what we sense as “free will.” The research could help shed light on a centuries-old debate about what free will is—and whether anyone really has it, or whether, instead, a mindless movement of atoms in our brains ultimately controls all decisions. The study appears in the May 16 issue of the research journal PLoS One. “Animals and especially insects are usually seen as complex robots which only respond to external stimuli,” said senior author Björn Brembs from the Free University Berlin. When scientists see animals responding differently even to the same stimuli, they typically “attribute this variability to random errors in a complex brain.” Using a combination of automated behavior recording and mathematical analyses, the team of researchers found that such variability cannot be due to simple random events but is generated spontaneously and non-randomly by the brain. These results caught computer scientist and lead author Alexander Maye from the University of Hamburg, Germany by surprise: “I would have never guessed that simple flies who otherwise keep bouncing off the same window have the capacity for nonrandom spontaneity if given the chance.” The researchers tethered fruit flies, Drosophila melanogaster, in uniform white surroundings and recorded their turning behavior. The flies in this setup receive no visual cues from the environment and since they are fixed in space, their turning attempts have no effect. Thus lacking any input, their behavior should resemble random noise, similar to a radio tuned between stations, the invest igators reasoned. However, the analysis found that fly behavior is very different. Various increasingly complex random computer models failed to adequately account fly behavior, the researchers said. They found the source of the spontaneity, they added, after analyzing the behavior with methods developed by co-authors George Sugihara and Chih-hao Hsieh from the Scripps Institution of Oceanography at the University of California San Diego. “We found that there must be an evolved function in the fly brain which leads to spontaneous variations in fly behavior” Sugihara said. “The results of our analysis indicate a mechanism which might be common to many other animals and could form the biological foundation for what we experience as free will.” Our subjective notion of “Free Will” is an oxymoron: the term ‘will’ would not apply if our actions were completely random and it would not be ‘free’ if they were entirely determined, Brembs remarked. So if there is free will, it must be somewhere between chance and necessity—just where fly behavior lies. “The question of whether or not we have free will appears to be posed the wrong way,” said Brembs. “Instead, if we ask ‘how close to free will are we’ one finds that this is precisely where humans and animals differ.” The next step will be to use genetics to localize and understand the brain circuits responsible for the spontaneous behavior, researchers added. This could lead to the development of robots with the capacity for spontaneous nonrandom behavior and may help combating disorders leading to compromised spontaneous behavioral variability in humans such as depression, schizophrenia or obsessive compulsive disorder.