THE Greek founders of philosophy constantly debated how best to live the good life. Some contended that personal pleasure is the key. Others pointed out that serving society and finding purpose is vital. Socrates was in the latter camp, fiercely arguing that an unvirtuous person could not be happy, and that a virtuous person could not fail to be happy. These days, psychologists tend to regard that point as moot, since self-serving “hedonic” pleasures generate the same sorts of good feelings as those generated by serving some greater “eudaimonic” purpose. However, a study just published in the Proceedings of the National Academy of Sciences, by Barbara Fredrickson, a psychologist at the University of North Carolina, Chapel Hill, and her colleagues suggests Socrates had a point. Though both hedonic and eudaimonic behaviour bring pleasure, the eudaimonic sort also brings health. Dr Fredrickson, an expert on positive emotions, has long known that happiness benefits health and leads to longer lives. Similarly, she knows that both hedonic and eudaimonic pleasures generate feelings that people describe as “happiness”. A simple syllogism, therefore, suggests happiness does indeed bring health and longevity. But, because of the overlap between the happiness-generating properties of both hedonic and eudaimonic pleasures, she had until she conducted this study found it impossible to determine whether both are able improve physical health and longevity, or whether only one of them can.

To solve the puzzle, she and a team of genomics researchers led by Steven Cole of the University of California, Los Angeles, recruited 84 volunteers for an experiment that examined genes associated with health while simultaneously probing happiness in a way that would tease apart hedonic and eudaimonic well-being. The team interviewed participants over the phone to make sure none suffered from any chronic illness or disability (four were eliminated this way). The rest were given online questionnaires in which they were asked questions that probed their happiness. These included, “In the past week how often did you feel happy?” and, “How often did you feel satisfied?” both of which were intended to assess hedonic well being. To assess eudaimonic well being they asked questions like, “In the past week how often did you feel that your life had a sense of direction or meaning to it?” and “How often did you feel that you had something to contribute to society?” The answers to these questions could score from nought to five points. Nought indicated “never”. Five indicated “every day”. The questionnaires also collected information on participants’ age, sex, race, smoking, alcohol consumption and recent symptoms of minor illness, like headaches and upset stomachs.

In addition to the answers to the questions, participants provided the team with a 20cc sample of blood. These samples were centrifuged to isolate the immune-system cells in them, and those cells were then analysed to see which genes were active.

At this, genetic, level, Dr Fredrickson and Dr Cole report, the two forms of happiness could hardly be more different. In volunteers who scored strongly for hedonic well-being and weakly for eudaimonic well-being inflammation-causing genes were 20% more active than average, and genes associated with the production of virus-attacking antibodies 20% less active. In contrast, in those who were the other way round, genes associated with the production of interferons (proteins that support communication during immune-system responses) were 10% more active and antibody genes 30% more active. Eudaimonic pleasure thus looks as though it is good for the health, while hedonic pleasure is bad.

Of course, these are extreme cases. In those who indulge in both forms of pleasure seeking the one effect cancels out the other. And it is possilbe, at least in theory, that causation runs in the opposite direction: people with particular patterns of gene expression could be healthier and thus, perhaps, take a longer view of life, which might in turn be conducive to eudaimonia. But differences of this sort in expression patterns within a single cell type are usually the result of signals to the cell, rather than being endogenous—which they would have to be if they were the underlying cause. That said, eudaimonia and health-giving expression patterns could be independent outcomes of some third, unidentified factor.

Nevertheless, if these molecular results do translate into bodily health in the way that might be predicted, it suggest Socrates was right, and that selfless, public-spirited individuals and selfish pleasure-seekers alike will receive their rewards and punishments here on Earth, without the need for the threat or promise of an afterlife.