If these 2 explorers were slightly fatter, it might have never happened. Find out more: http://www.pbs.org/wgbh/nova/evolution/dawn-of-humanity.html http://news.nationalgeographic.com/2015/09/150910-human-evolution-change/ http://www.vox.com/2015/9/10/9301479/homo-naledi-species-hominin? Subscribe to our channel! http://goo.gl/0bsAjO Vox.com is a news website that helps you cut through the noise and understand what's really driving the events in the headlines. Check out http://www.vox.com to get up to speed on everything from Kurdistan to the Kim Kardashian app. Check out our full video catalog: http://goo.gl/IZONyE Follow Vox on Twitter: http://goo.gl/XFrZ5H Or on Facebook: http://goo.gl/U2g06o