It makes sense that cats and humans are the two most popular organisms on the Internet since they are also two of the few animals that kill for fun. The bizarre pleasure derived from hurting another creature is at the heart of many Internet social exchanges. For many of us, the tone of this discourse is troubling. For online publications and social networks, the spewing rage can be an existential threat. Can software and design tweaks based on behavioral psychology keep us in line? From The Guardian’s Gaby Hinsliff: How the internet is trying to design out toxic behavior.