Injuries among small kids under five mysteriously increased 10 percent between 2005 and 2012. New research points the blame at an unlikely cuprit: the iPhone. Specifically, iPhones that distract parents from keeping an eye on their children.

The Upshot flags a fascinating new study looking at the rise in unintentional injuries among young children since 2007 — the same year that the first iPhone came onto the market. This has led to a bit of armchair hypothesizing that smartphones were distracting parents from watching their kids at the playground or in the pool, and allowing more injuries to occur.

There are lots of spurious correlations in the world (Exhibit A: the strong relationship between Nicholas Cage movies and people drowning in pools) and, up until now, we've had no evidence of any relationship between the rise of iPhones and childhood injuries. Enter Craig Palsson, a graduate student in economics at Yale University, who recently posted research suggesting there could be a causal relationship between smartphones and broken bones.

Palsson's new paper looks at the expansion of AT&T's 3G network into new cities — the data network helped make smartphones way more powerful and thus distracting — and where kids were having more injuries. He finds the two trends moving in the same direction. Hospitals only saw an increase in child injuries "after AT&T expanded its 3G network into the area," Palsson writes.

Also notable: the increase in injuries was largest among younger children (who are tend to need more supervision) and in the types of activities that parents typically supervise (like playing on a playground not in sporting events, where injuries would happen regardless of how much attention parents pay.)

This paper comes with all the typical caveats of any academic paper. It is one piece of evidence and its possible, if other researchers step into the field, they'll find something different. But Palsson argues that "smartphones have caused an increase in childhood injuries" well beyond what would have happened in an iPhone-less world.