David Dobbs has a fantastic new article on behavioral genetics at The Atlantic. He adds an important amendment to the vulnerability hypothesis, which holds that certain genes make people more vulnerable to psychiatric disorders. While these snippets of DNA aren't deterministic per se, when they are combined with traumatic childhood events, or a stressful few months, they can lead to serious mental illness. It's the old genes plus environment story, and it's typically cast in a negative light. But Dobbs finds that the vulnerability hypothesis comes with a positive (and often overlooked) flip-side:
At first glance, this idea, which I'll call the orchid hypothesis, may seem a simple amendment to the vulnerability hypothesis. It merely adds that environment and experience can steer a person up instead of down. Yet it's actually a completely new way to think about genetics and human behavior. Risk becomes possibility; vulnerability becomes plasticity and responsiveness. It's one of those simple ideas with big, spreading implications. Gene variants generally considered misfortunes (poor Jim, he got the "bad" gene) can instead now be understood as highly leveraged evolutionary bets, with both high risks and high potential rewards: gambles that help create a diversified-portfolio approach to survival, with selection favoring parents who happen to invest in both dandelions and orchids.
In this view, having both dandelion and orchid kids greatly raises a family's (and a species') chance of succeeding, over time and in any given environment. The behavioral diversity provided by these two different types of temperament also supplies precisely what a smart, strong species needs if it is to spread across and dominate a changing world. The many dandelions in a population provide an underlying stability. The less-numerous orchids, meanwhile, may falter in some environments but can excel in those that suit them. And even when they lead troubled early lives, some of the resulting heightened responses to adversity that can be problematic in everyday life--increased novelty-seeking, restlessness of attention, elevated risk-taking, or aggression--can prove advantageous in certain challenging situations: wars, tribal or modern; social strife of many kinds; and migrations to new environments. Together, the steady dandelions and the mercurial orchids offer an adaptive flexibility that neither can provide alone. Together, they open a path to otherwise unreachable individual and collective achievements.
This orchid hypothesis also answers a fundamental evolutionary question that the vulnerability hypothesis cannot. If variants of certain genes create mainly dysfunction and trouble, how have they survived natural selection? Genes so maladaptive should have been selected out. Yet about a quarter of all human beings carry the best-documented gene variant for depression, while more than a fifth carry the variant that Bakermans-Kranenburg studied, which is associated with externalizing, antisocial, and violent behaviors, as well as ADHD, anxiety, and depression. The vulnerability hypothesis can't account for this. The orchid hypothesis can.
This is a transformative, even startling view of human frailty and strength. For more than a decade, proponents of the vulnerability hypothesis have argued that certain gene variants underlie some of humankind's most grievous problems: despair, alienation, cruelties both petty and epic. The orchid hypothesis accepts that proposition. But it adds, tantalizingly, that these same troublesome genes play a critical role in our species' astounding success.
The orchid hypothesis--sometimes called the plasticity hypothesis, the sensitivity hypothesis, or the differential-susceptibility hypothesis--is too new to have been tested widely. Many researchers, even those in behavioral science, know little or nothing of the idea. A few--chiefly those with broad reservations about ever tying specific genes to specific behaviors--express concerns. But as more supporting evidence emerges, the most common reaction to the idea among researchers and clinicians is excitement. A growing number of psychologists, psychiatrists, child-development experts, geneticists, ethologists, and others are beginning to believe that, as Karlen Lyons-Ruth, a developmental psychologist at Harvard Medical School, puts it, "It's time to take this seriously."
Is this really about giving our genetically determined predispositions a greater range of optional strategies to go with certain of those traits as an adaptive reaction to more complicated environmental challenges? And with more options comes more risk of some misdirection of their purposes?
If so, it may also show that we have more to do with influencing the speed of our own evolutionary development as a direct response to environmental and cultural change than the traditional view of the mechanism has accounted for.
The claim that this is a "completely new way of thinking about genetics and human behavior" is pure pitch.
The real insight here is that "mental disease" is not only created/incited by environmental factors but is also *defined* by the environment. Mental disease is a brain state that we define as debilitating.
Evolution has not kept up with the changes in environment--we went from hunters/farmers to office workers in 100 years. The expression of mental disease (and thus the expression of the associated "genetic risk factors")is completely different in a new environment.
If we were to take someone with ADHD out of the office and then send them back to a time when there was a need for hunters and explorers, we would view this condition/brain state/genetic predisposition differently.
Could this go for any mental/beahavior disease that is acquired over time? Maybe. Truth is that its hard to understand one's place in the entire chain of the human population, particularly in an environment completely different from the one we've experienced.
When I think about the flip sides of genetic predispositions I think of ADD and ADHD. An increasing number of patients seem to present with these symptoms. I think the advances of technology and the way we raise children plays a role in the number of increased cases. Speed and end results are emphasized. The process or steps inherent in learning are seldom taught. For some people with the genetic predisposition this may exacerbate a vulnerability that makes it difficult for them to function. (ADD/ADHD).
For a small number of individuals that same predisposition may help them to excel in our new faster, higher tech age. They adapt faster to the rapid change in technology and seem to process incoming data more quickly and their multitasking becomes an asset. An individualâs genetic predispositions, previously a possible vulnerability, may play a role in adaptation as the demands of the environment change.
Very compelling evidence for the plasticity hypothesis suddenly surfaces if you think about oncogenetics in this vein. I've always felt that the eventual successful cure or treatment of cancers will be based on such an evolutionary re-understanding of oncogenes.
It helps immensely, if as a parent or caregiver, or as an individual you can see any occurence or situation as a gift, including genetic 'shortcomings'. It may take awhile but there is always some compensatory value to everything annoying, and even downright terrible. Oliver Sacks, for example, is one who can see this in his patients and writes about it.
Larry Niven posited something like this in his story "Madness Has Its Place", in which paranoid schizophrenics go off their meds one weekend a month in order to act as part of the intelligence gathering/analysis operations for the government.
The movie Precious, opened last night in Baltimore. It begins with a quote from Ken Kesey, jr. that goes something like..."Everything is a gift from the universe" and then vibrantly and eloqunetly shows that this is so. See it.