The United States has stumbled into a potential military confrontation with Russia over Ukraine - a dangerous predicament that could become a Cuban Missile Crisis in reverse.
The "Black Death" moved across Eurasia, driven by climate events that were and still are frequently occurring.
Nikki Willoughby is social media manager at Common Cause. She oversees community action and serves as editor of the CommonBlog. Find her on Twitter @Nikki4CC or email her at email@example.com.