Is the battle for the GOP presidential nomination about history? Or is it about math? Santorum may be getting big headlines with his primary wins, but it's Romney who is advancing further to the magic 1,144 number. And more defeats mean more pressure on Gingrich to pull out.

Business and political leaders have repeatedly warned that America's scientists and engineers are in short supply. However, some economists say the numbers indicate the opposite — a glut of high-tech workers. A panel of experts debate whether America's schools produce the scientific workforce needed to compete globally.

Recent events have renewed calls to pull out U.S. troops before a 2014 deadline. Host Michel Martin hears two perspectives: Iraq war veteran Jon Soltz believes the current counterinsurgency strategy isn't yielding enough results, but Gayle Tzemach Lemmon believes if the U.S. pulls out now, Afghan civil society could face serious consequences.

Some observers say race may have played a role in the shooting of 17-year-old African-American Trayvon Martin. The shooter says it was self defense, but Martin's family says the boy was unarmed and are demanding Florida authorities press charges. Host Michel Martin speaks with Miami Herald reporter Frances Robles.

Scientists trying to decipher the source of pine nut mouth, a vile taste some people get after eating the nutritious nuts, say they've been stumped in trying to detect a chemical signature for the problem.

An estimated 70 percent of the ground beef supply contains these lean bits of meat derived from muscle and connective tissue. The industry calls the trimmings Lean Finely Textured Beef.

The Taliban has announced it is suspending peace talks with the U.S. At the same time, Afghan President Hamid Karzai demanded the U.S. pull troops out of rural areas by next year following a deadly shooting spree by an American soldier. These signals have come at an already difficult time for the U.S. in Afghanistan and further complicate the U.S. exit strategy.

In NCAA men's basketball action Thursday night, Iowa State defeated the the University of Connecticut 77-64. The Huskies were last year's champions. Also, VCU beat Wichita State 62-59 to advance to weekend play.