For some kids who grow up in poverty, the bond developed with Mom is especially important in dealing with stress. iStockphoto.com hide caption

Kenyan authorities are trying to guard against fraud and violence when they hold a presidential election on March 4. Here, voters register on biometric equipment last December in Nairobi. Simon Maina/AFP/Getty Images hide caption

Iowa Gov. Terry Branstad speaks during a panel discussion at the National Governors Association 2013 Winter Meeting in Washington, D.C. Manuel Balce Ceneta/AP hide caption

A young demonstrator is attacked by a police dog in Birmingham, Ala., in May 1963. Scenes like these helped usher in the nation's landmark civil rights law, the 1965 Voting Rights Act. The Supreme Court will hear arguments Wednesday over a key provision of the law. Bill Hudson/AP hide caption

Steve Harvey on the set of his Steve Harvey Show in Chicago just before it debuted in September 2012. Chuck Hodes/AP/NBC hide caption

Caitlin J. Halligan, shown in 2005, waited more than 700 days in the last Congress for a vote on the Senate floor before she was filibustered, the White House says. She was nominated again last month. Jim McKnight/AP hide caption

Wal-Mart is one of several large retailers that say an increase in the payroll tax may hurt U.S. sales in the months ahead. Daniel Acker/Bloomberg via Getty Images hide caption