Historian, economist, and speaker, Neil Howe discussed his work on generations and how they shape history, as well as the twenty year cycle of crisis facing the U.S. as predicted in his book "The Fourth Turning." He outlined some of the traits of the currently living sets of American generations-- G.I.s (born from 1901 to 1924), Silent (born from 1925 to 1942), Boomers (1943-1960), Gen Xers (1961-1981), and Millennials (born 1982 and later). These traits were listed in a previous recap.

He defined the Fourth Turning as an era when all the living generations start moving into the next phase of life. Howe believes we are seeing this play out now, with 2008 as a critical transition year. Millennials are beginning to come of age, with Gen X-ers taking over mid-life roles of leadership (Barack Obama is America's first Gen X-er President), Boomers starting to retire, and the Silents firmly entrenched as senior citizens. Interestingly, the generation that enters a new age bracket transforms and reshapes that segment of the population, and marketers often try to sell their products to age with a particular generation, Howe detailed.

When the generation who lived after the last major crisis starts entering old age, they typically take the country into the next crisis, such as with the Great Depression, WWII, and the American Revolution, he explained. Howe also described how other countries such as China and England experience generational shifts in their populations as well.

Oil Spill Solutions

First hour guest, science writer Charles Seife talked about different possible solutions to the BP oil spill. At one time, the Soviet Union used atomic blasts to successfully stop runaway fires in gas wells, he noted. However, given the location of the Gulf oil leak, such a solution would probably make the situation worse, he said.