David Brooks in today's New York Times: "Studies designed to link specific genes to behavior have failed to find anything larger than very small associations. It’s now clear 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. Prof. Eric Turkheimer of the University of Virginia, conducted research showing that growing up in an impoverished environment harms I.Q. 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...
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."
As always, we humans give ourselves too much credit. We think our little brains can comprehend the complexity of the universe, but once we pull back the covers, we're surprised again and again at how much we do not (and probably cannot) understand. All the more reason why we should aim to design systems that allow for such complexity, instead of unidimensional edicts that arrogantly believe they can account for all of it.