American Guns, Lightning & Phosphorus, Narwhal Tusk

How guns from America end up arming gangs and cartels in major US cities and across Latin America. Also, lightning may have been the crucial ingredient that sparked life to form on Earth billions of years ago. Then, what Narwhal tusks teach us about climate change. Also on today's show: how a common type of commercial fishing is adding to the planet’s carbon emissions, and why the Dominican Republic is a top recruiting ground for Major League Baseball. (AP Photo/Jae C. Hong, File)