Changing marriage patterns in the U.S. may help explain why low- income males are losing ground to their higher-earning counterparts, according to a study by the Brookings Institution's Gary Burtless.

• The average earnings of the top fifth of male earners increased 4 percent between 1979 and 1996 -- but fell by 44 percent for those in the bottom fifth.

• In 1979, 57 percent of the poorest fifth of men were married -- but only 43 percent were by 1996.

• Burtless notes that poor single men do not share a wife's income, while the wives of upper-income males now go out to work more.

• Over the same period, the average earnings of wealthy men's wives shot up 113 percent -- while those of poor men's wives increased only 35 percent.

So the decline in marriage over the past two decades has affected poor men more than most. Also, rich men apparently have less trouble finding wives.

Source: "Poor and Single," Economist, January 16, 1999.