It Takes a Genome: How a Clash Between Our Genes and Modern Life Is Making Us Sick

An Epidemic of Mood Swings

At any given time, somewhere in the vicinity of four percent of women between the ages of 25 and 45, and two percent of men, are clinically depressed. These are conservative estimates. They mean that without a doubt someone in your neighborhood or workplace is struggling mightily to face each day with characteristic cheer. Multiply them by five to obtain the number of people experiencing the blues, and double again to arrive at a lifetime estimate of the fraction of the population that experiences at least one somewhat debilitating episode of depression.

As far as we know, this disease recognizes no ethnic or socioeconomic boundaries, though of course it is almost impossible to know. Many countries refuse to recognize ...