The phrase “nature versus nurture” still heavily influences perceptions of human behavior, at least in the minds of the public. But gene researchers and neurobiologists also grapple with the concept, speakers said at a recent AAAS event, when they explore how biology and environment shape human personality.
Rather than focus on dueling forces, scientists should stress that human development is the product of complex, interwoven systems, said Denis Alexander, a molecular biologist and emeritus director of the Faraday Institute for Science and Religion.
Not only is genetic determinism misleading, Alexander said, but it also can have a negative effect on the public. Studies have shown that believing one’s capabilities are predestined, he noted, can impact “a range of psychological traits and human behaviors.”
The field of neuroscience faces similar issues, said broadcast journalist Steve Paulson. Some scientists in the field argue that the brain dictates all of human behavior, and that free will does not exist.
“Just as Denis has asked, ‘Are we only our genes?’ there is a follow-up question: ‘Are we only our brains?’” Paulson said. “And, if everything in our minds can be reduced to brain chemistry, where does that leave us?”
The 13 December lecture was presented by AAAS’s Dialogue on Science, Ethics and Religion (DoSER). Founded in 1995, DoSER builds on AAAS’s commitment to relate scientific knowledge to the concerns of society at large by facilitating communication between scientific and religious communities.
“For some, an inflated sense of genetic or neurological determinism may create a kind of fatalism that erodes recognition of authentic human freedom and moral responsibility,” said DoSER Director Jennifer Wiseman, in her comments at the event.
The field of genetics has made landmark advances in recent years, and is becoming increasingly integrated into popular culture. Researchers finished mapping the complete human genome in 2004, and are now uncovering the functions of a growing number of genes. While scientists have generally avoided stating that these genes code “for” particular personality traits, the media has not been so careful when reporting on genetic research.
“The phrase, ‘It’s in his or her DNA,’ has come into our daily language to suggest a particular characteristic is intrinsic,” Alexander said, “and may be rather difficult to change.”
He presented a study published in Nature as an example of how the media can misinterpret scientific research. Within a Finnish population, researchers found a mutation in a gene linked to changes in mood and behavior in 17 out of 228 violent, imprisoned individuals with high impulsivity, compared to seven out of 295 control individuals.
About 106,000 people in the Finnish population carry this mutation, while only 3500 of the population is in prison. Thus, “the majority of people with this mutation are not violent offenders,” Alexander explained, saying the study does not serve as evidence for genetic determinism.
Nonetheless, he noted, media coverage of the Nature study included statements such as, “Drunken rage could be in your genes.”
This matters, Alexander reiterated, because people are affected when they view themselves as puppets with “genes pulling the strings.”
“Genes maybe influence us,” he said, “but they certainly don’t control us, as if our genes and our genomes were somehow operating in a separate space from the rest of our personhood.”
Scientists can do more justice to contemporary biology by presenting human development as the product of a complex system, Alexander said. He suggested a new acronym to guide the discussion of genetic research: DICI, for Developmental, Integrated, Complementary, Interactionism.
From zygote to adulthood, both genetics and the environment shape people and are of fundamental importance. The nutrients a fetus absorbs, the sensory perceptions received inside and outside the womb, and decisions made as adults—about such things as alcohol intake or diet, for example—are just a few factors that can affect gene expression and development.
“In reality, there are many tributaries of the river of life flowing together to cause the emergence of the unique human individual.” he added.
Are We Only Our Brains?
While most genetic researchers deny that genes completely control human destiny, some neuroscientists argue that the brain controls and predicts all of human behavior, and that free will is an illusion.
The thought that our brains know what we’re going to do before we do it stems from an experiment conducted by Benjamin Libet in the 1980s. He found that electrical impulses fired in the brain about half a second before individuals were consciously aware of their decision to push a button, Paulson explained.
“The assumption here is that we are not actually making decisions,” Paulson said, “as if we have two competing selves—a civilized, conscious self, and a secret subconscious—dictating what we really think and do.”
However, Paulson said there are problems with neural determinism. First, cognition may not happen only in the brain. Paulson referenced the work of award-winning jazz pianist Vijay Iyer, who also has a Ph.D. from the University of California, Berkeley in technology and the arts. Iyer’s research indicates that musical cognition and perception involves the whole body, as well as the surrounding environment of a performer or listener.
Paulson also alluded to research that suggests meditation can change how the brain works. And many neuroscientists have said they will never be able to “isolate the precise neurons to explain why a particular thought pops into our heads,” he added.
“It is almost scientific orthodoxy to say that the brain generates all our conscious experiences, but no one has a clue how this happens,” Paulson said. This identifies a gap, he said, in understanding between the physical brain and immaterial thoughts.
“This is a golden age for the science of the brain,” Paulson said. “But I think we need to be careful about what lessons to draw from these discoveries. It’s entirely possible that science will never be able to explain certain parts of our lives, and that is OK.”
In a question and answer session after the discussion, Paulson said scholars are beginning to explore the idea that consciousness exists as a fundamental property in nature, and that it can’t be reduced to physics, chemistry, or biology. It’s a notion that inevitably touches on religious beliefs about life after death.
However, Alexander said he doesn’t think any scientific data address the particular question of whether consciousness is separate from the body.
“There are so many other ways of understanding this. I think that one should be a little cautious about extrapolating the data too far,” he said. “I happen to be Christian, so I do believe that clearly there will be a resurrection of the body…[But] it depends very much on one’s own framework, and where one’s coming from.”
Wiseman asked if the discussion of determinism is a “separate conversation” in neuroscience and genetics. Paulson and Alexander said that the idea of determinism does differ between disciplines, especially as the research in each field becomes more specialized.
“It’s quite hard sometimes, I think, for people inside their own specialized research field to stand back and see the picture as a whole,” Alexander explained. He warned that the public should be skeptical of research claiming that human identity was “nothing but its particular level of description…There are many complementary stories to be told.”Learn more about the AAAS Dialogue on Science, Ethics and Religion.