title: How to make this graph in R
body: <p>Do you know what this kind of graph is called, and how can I make it in R?</p>
  
  <p>Thanks-</p>
  
  <p><img src="https://i.stack.imgur.com/aFs37.jpg" alt="enter image description here"></p>
  
  <p>Source of the image: <a href="http://www.wired.com/2014/05/alumni-network-2/" rel="nofollow noreferrer">http://www.wired.com/2014/05/alumni-network-2/</a></p>