"Poverty in early childhood poisons the brain." That was the opening of an article in Saturday's Financial Times, summarizing research presented last week at the American Association for the Advancement of Science.
As the article explained, neuroscientists have found that "many children growing up in very poor families with low social status experience unhealthy levels of stress hormones, which impair their neural development." The effect is to impair language development and memory - and hence the ability to escape poverty - for the rest of the child's life.
So now we have another, even more compelling reason to be ashamed about America's record of failing to fight poverty.
L. B. J. declared his "War on Poverty" 44 years ago. Contrary to cynical legend, there actually was a large reduction in poverty over the next few years, especially among children, who saw their poverty rate fall from 23 percent in 1963 to 14 percent in 1969.
But progress stalled thereafter: American politics shifted to the right, attention shifted from the suffering of the poor to the alleged abuses of welfare queens driving Cadillacs, and the fight against poverty was largely abandoned.
In 2006, 17.4 percent of children in America lived below the poverty line, substantially more than in 1969. And even this measure probably understates the true depth of many children's misery.
Living in or near poverty has always been a form of exile, of being cut off from the larger society. But the distance between the poor and the rest of us is much greater than it was 40 years ago, because most American incomes have risen in real terms while the official poverty line has not. To be poor in America today, even more than in the past, is to be an outcast in your own country. And that, the neuroscientists tell us, is what poisons a child's brain.
America's failure to make progress in reducing poverty, especially among children, should provoke a lot of soul-searching. Unfortunately, what it often seems to provoke instead is great creativity in making excuses.
Some of these excuses take the form of assertions that America's poor really aren't all that poor - a claim that always has me wondering whether those making it watched any TV during Hurricane Katrina, or for that matter have ever looked around them while visiting a major American city.
Mainly, however, excuses for poverty involve the assertion that the United States is a land of opportunity, a place where people can start out poor, work hard and become rich.
But the fact of the matter is that Horatio Alger stories are rare, and stories of people trapped by their parents' poverty are all too common. According to one recent estimate, American children born to parents in the bottom fourth of the income distribution have almost a 50 percent chance of staying there - and almost a two-thirds chance of remaining stuck if they're black.
That's not surprising. Growing up in poverty puts you at a disadvantage at every step.
I'd bracket those new studies on brain development in early childhood with a study from the National Center for Education Statistics, which tracked a group of students who were in eighth grade in 1988. The study found, roughly speaking, that in modern America parental status trumps ability: students who did very well on a standardized test but came from low-status families were slightly less likely to get through college than students who tested poorly but had well-off parents.
None of this is inevitable.
Poverty rates are much lower in most European countries than in the United States, mainly because of government programs that help the poor and unlucky.
And governments that set their minds to it can reduce poverty. In Britain, the Labor government that came into office in 1997 made reducing poverty a priority - and despite some setbacks, its program of income subsidies and other aid has achieved a great deal. Child poverty, in particular, has been cut in half by the measure that corresponds most closely to the U.S. definition.
At the moment it's hard to imagine anything comparable happening in this country. To their credit - and to the credit of John Edwards, who goaded them into it - both Hillary Clinton and Barack Obama are proposing new initiatives against poverty. But their proposals are modest in scope and far from central to their campaigns.
I'm not blaming them for that; if a progressive wins this election, it will be by promising to ease the anxiety of the middle class rather than aiding the poor. And for a variety of reasons, health care, not poverty, should be the first priority of a Democratic administration.
But ultimately, let's hope that the nation turns back to the task it abandoned - that of ending the poverty that still poisons so many American lives.
Paul Krugman is Professor of Economics at Princeton University and a regular New York Times columnist. His most recent book is The Conscience of a Liberal.
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