We all know the story of Dr. Frankenstein, the scientist so caught up in his own research that he arrogantly tried to create new life and a new man. Today, if you look at people who study how genetics shape human behavior, you find a collection of anti-Frankensteins. As the research moves along, the scientists grow more modest about what we are close to knowing and achieving.
It wasn't long ago that headlines were blaring about the discovery of an aggression gene, a happiness gene or a depression gene. The implication was obvious: We're beginning to understand the wellsprings of human behavior, and it won't be long before we can begin to intervene to enhance or transform human life.
Few talk that way now. There seems to be a general feeling, as a Hastings Center working group put it, that "behavioral genetics will never explain as much of human behavior as was once promised."
Studies designed to link specific genes to behavior have failed to find anything larger than very small associations. It's now clear that that one gene almost never leads to one trait. Instead, a specific trait may be the result of the interplay of hundreds of different genes interacting with an infinitude of environmental factors.
First, there is the complexity of the genetic process. As Jim J. Manzi pointed out in a recent essay in National Review, if a trait like aggressiveness is influenced by just 100 genes, and each of those genes can be turned on or off, then there are a trillion trillion possible combinations of these gene states.
Second, because genes respond to environmental signals, there's the complexity of the world around. Professor Eric Turkheimer of the University of Virginia, conducted research showing that growing up in an impoverished environment harms IQ. He was asked what specific interventions would help children realize their potential. But, he noted, that he had no good reply. Poverty as a whole has this important impact on people, but when you try to dissect poverty and find out which specific elements have the biggest impact, you find that no single factor really explains very much. It's possible to detect the total outcome of a general situation. It's harder to draw a linear relationship showing cause and effect.
Third, there is the fuzziness of the words we use to describe ourselves. We talk about depression, anxiety and happiness, but it's not clear how the words that we use to describe what we feel correspond to biological processes. It could be that we use one word, depression, to describe many different things, or perhaps depression is merely a symptom of deeper processes that we're not aware of. In the current issue of Nature, there is an essay about the arguments between geneticists and neuroscientists as they try to figure out exactly what it is that they are talking about.
The bottom line is this: For a time, it seemed as if we were about to use the bright beam of science to illuminate the murky world of human action. Instead, as Turkheimer writes in his chapter in the book, "Wrestling With Behavioral Genetics," science finds itself enmeshed with social science and the humanities in what researchers call the Gloomy Prospect, the ineffable mystery of why people do what they do.
The prospect may be gloomy for those who seek to understand human behavior, but the flip side is the reminder that each of us is a Luxurious Growth. Our lives are not determined by uniform processes. Instead, human behavior is complex, nonlinear and unpredictable. The Brave New World is far away. Novels and history can still produce insights into human behavior that science can't match.
Just as important is the implication for politics. Starting in the late 19th century, eugenicists used primitive ideas about genetics to try to re-engineer the human race. In the 20th century, Communists used primitive ideas about "scientific materialism" to try to re-engineer a New Soviet Man.
Today, we have access to our own genetic recipe. But we seem not to be falling into the arrogant temptation - to try to re-engineer society on the basis of what we think we know. Saying farewell to the sort of horrible social engineering projects that dominated the 20th century is a major example of human progress.
We can strive to eliminate that multivariate thing we call poverty. We can take people out of environments that (somehow) produce bad outcomes and try to immerse them into environments that (somehow) produce better ones. But we're not close to understanding how A leads to B, and probably never will be.
This age of tremendous scientific achievement has underlined an ancient philosophic truth - that there are severe limits to what we know and can know; that the best political actions are incremental, respectful toward accumulated practice and more attuned to particular circumstances than universal laws.