The site at Gobekli Tepe, or "Potbelly Hill," on the Urfa plain in southeastern Turkey is believed by some to be the world's first place of worship. This would upend the conventional thought that religion developed as a byproduct of human settlements. Vincent J. Musi/National Geographic Society/Corbis hide caption

itoggle caption Vincent J. Musi/National Geographic Society/Corbis

A Free Syrian Army fighter runs after attacking a tank with a rocket-propelled grenade during fighting in Aleppo, Syria, in September 2012. The rebels say they are willing to take on the Islamic State, but need more weapons. Manu Brabo/AP hide caption

itoggle caption Manu Brabo/AP

Thick smoke rises following an airstrike by the U.S.-led coalition in Kobani, Syria, while fighting continued between Syrian Kurds and the militants of the self-proclaimed Islamic State, as seen from Mursitpinar on the outskirts of Suruc, at the Turkey-Syria border on Wednesday. Lefteris Pitarakis/AP hide caption

itoggle caption Lefteris Pitarakis/AP

Syrian Kurdish refugees who fled Kobani make do in a refugee camp in Suruc, on the Turkey-Syria border on Saturday. The Syrian Kurdish border town of Kobani and its surrounding areas have been under assault by the so-called Islamic State since mid-September. Lefteris Pitarakis/AP hide caption

itoggle caption Lefteris Pitarakis/AP

"Today's anti-Westernism is a reaction to yesterday's racism," Iranian President Hassan Rouhani said in a speech at the U.N. General Assembly on Thursday. Jason DeCrow/AP hide caption

itoggle caption Jason DeCrow/AP

An Iranian security guard directs media at the Bushehr nuclear power plant in 2010. The crisis in Ukraine, the Ebola outbreak in Africa and extremist violence in Iraq all threaten to complicate the nuclear talks. Vahid Salemi/AP hide caption

itoggle caption Vahid Salemi/AP

Displaced Iraqis from the Yazidi community settle under a bridge in central Dahuk, Aug. 14. Human rights activists say evidence of the Islamic State's violence against the Yazidis points to war crimes, and amounts to ethnic cleansing. Khalid Mohammed/AP hide caption

itoggle caption Khalid Mohammed/AP