As parents know instinctively, some babies are just born happy.
But neuroscientists have also learned over the past decade that the brain is highly plastic. It rewires itself in response to experience, and that’s especially true before the age of puberty. One might naively assume, therefore, that negative experiences might destroy a happy personality–and if they’re extreme and frequent enough, that might be true.
Davidson has learned, however, that mild to moderate doses of negative experience are beneficial. (In animal studies, he compared groups that had been moderately stressed when young to those that never were and found the former better able to recover from stress as adults.
In human studies, in which deliberately inducing stress on kids would be unethical, he based his conclusions on self-reported stories of stressful childhoods.) The reason, he believes, is that stressful events give us practice at bouncing back from unpleasant emotions.
They’re like an exercise to strengthen our happiness muscles or a vaccination against melancholy.
Source: Health: The Biology of Joy. Scientists know plenty about depression. Now they are starting to understand the roots of positive emotion by Michael D. Lemonick Sunday, Jan. 09, 2005 The Time