A look at how a period of climate change millions of years ago impacted evolution.

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In this History Uncut video clip, watch actual video footage of Al Gore in 1997 as he presents a speech on global warming and climate change. He states, "Global climate disruption is the biggest threat to our future".

The Roman forum was more than just home to their Senate.

Look back at some of the moments when the smartphone changed the course of history.

In a Path to the Podium video, see the Democratic presidential candidate, Barack Obama. Learn that in 2004, Obama's keynote speech at the Democratic National Convention catapulted him into the spotlight. In 2007, Obama announced his own candidacy for the President of the United States. Obama's rejection of the war in Iraq energizes his support base, but his youth and inexperience prove to be worrisome for others. Learn that in 1961, Obama was born to an American mother and Kenyan father in Hawaii. When Obama was only two years old, his father left; later his mother remarried and they moved to Indonesia. When Obama was ten, he returned to the United States to live with his grandparents, where his elite education began. Obama went on to study political science in Columbia University and then attend Harvard Law, where he becomes the first African American president of the Harvard Law Review. Obama meets his future wife Michelle Robinson at a Chicago law firm; they marry in 1992 and go on to have two daughters. In 1996, Obama runs for state senate and wins. He then runs for U.S. Senate in 2000, but does not win. The 2004 Democratic National Convention put Obama back on top, where Americans are seeing him today.

The Gutenberg Bible was the first book printed in Western Europe using movable metal type, introducing text reproduction to the masses.

Get a quick rundown of some things you might not know about the history of U.S. presidential elections.