He found, in an international survey of epidemiological studies, that beyond a certain level of material development, it was not the absolute levels of prosperity that affected health, but the distribution of income and wealth.
That poor people have poorer health than well-off people is not surprising; but that poor people in countries with relatively high equality have better health than well-off people in countries with high inequalities is very surprising. The Scandinavian countries are examples of the former, Britain and Brazil of the latter.
It is refreshing these days to find someone tackling big issues of distribution head on. Can any implications be drawn for education? I suggest two.
First, if motivation to learn is a key feature of a learning society, then high degrees of inequality are probably a demotivating factor. If colossal rewards are paid, it could of course be a supreme motivator - for the very few. But if the chances of getting the rewards are slim, the result may be that most will give up the chase. Moreover, if the rewards are paid on a seemingly arbitrary, or even perverse, basis, then this is likely to turn people on to other paths of reward-seeking than learning.
When someone in a merchant bank is offered Pounds 500,000 on a scrap of paper for doing a "great job" in supervising Nick Leeson, it somehow becomes a little less plausible to expect the rest of the population to keep their nose clean, beaver their way towards another couple of SVQs and assume that if they manage they, too, will have their fair share of the nation's enhanced wealth.
In so far as this is a joke, it is a very bad one, and highly injurious to learning.
I talked recently with a colleague from Boston, Massachusetts. There, black children's chances of having learning rewarded are pretty slim. A sadly high proportion of them, therefore, follow the rational economic path into drug-dealing.
Second, the higher the degree of inequality, the more likely it is that responsibility for learning will fall upon the individual alone. If they are going to benefit hugely from investment in their human capital, then the other potential stakeholders - employer or society - are more likely to leave it to them to assume the costs, since they will reap so much in the way of benefits.
If graduates get large salaries, and are taxed at low, perhaps non-existent rates, then why should the rest of society pay? There are potential reasons, of course - namely that the graduate's graduateness enables them to do such valuable work that everyone benefits, even if the graduate benefits most.
But there are probably limits to this line of thinking, and we increasingly accept that graduates should take a share in the pain since they take most of the gain. The problem is that this logic may then be extended to the rest of the population, who might not be nearly so well placed to manage their own learning, or to finance it on an extended basis.
I actually believe that we are not asking individuals to take enough responsibility for their learning. They are more likely to accept that responsibility if they feel they are part of a process in which several people have a stake.
The most important general point for me from the health study is that wider distributive patterns affect educational achievement, and not only in respect of children. It is not just the size of the inequalities that matters. It is also the extent to which people see that they are reasonable. The rhetoric of lifelong learning will cut little ice if the link between learning and reward is not fairly established in people's minds.