Alcohol. It's a dangerous drug that has ruined countless lives and derailed many a global summit. But it's also humanity's oldest social lubricant, a magical elixir that can fuel diplomatic breakthroughs, well into the wee hours of the night. As Winston Churchill once quipped, "I've taken more out of alcohol than alcohol has taken out of me." On GZERO World, we take a deep dive down the bottle and examine the role alcohol has played in society, politics, and global summitry—from the earliest hunter-gatherer days to that memorable Obama Beer Summit in 2009. Joining Ian Bremmer is philosopher Edward Slingerland, whose new book Drunk: How We Sipped, Danced, and Stumbled Our Way Into Civilization makes a compelling, if nuanced, case for alcohol's place in the world.

Also: since alcohol isn't the only social drug, a look at the state of marijuana legalization across the US and around the world.