Every six months or a year, a new app reignites a conversation about why people share on social media. I think it is pretty straight forward. Humans are social machines with thousands of years of evolutionary refinement. When we speak, emote or share, we each rapidly run a pretty sophisticated cost-benefit analysis of whether it is in our interest to express ourselves. If we determine that sharing is socially ROI positive—meaning it brings us some value—we share; if not, most of us keep it to ourselves.

So, the real question each time something like Snapchat, Instagram, Periscope or Meerkat arises is whether there is a new technological reality in the economics of sharing that makes the new activity ROI positive when it wasn’t previously. If some sort of economic calculus hasn’t changed, then it is hard to imagine that something that’s been tried and failed will take off.