Washington Post:

New research in biomechanics suggests that young people are developing hornlike spikes at the back of their skulls — bone spurs caused by the forward tilt of the head, which shifts weight from the spine to the muscles at the back of the head, causing bone growth in the connecting tendons and ligaments. The weight transfer that causes the buildup can be compared to the way the skin thickens into a callus as a response to pressure or abrasion.

The result is a hook or hornlike feature jutting out from the skull, just above the neck.

If you don’t have access to the article (and I find the Washington Post a no-brainer value, worth my subscription dollar), here’s a link to the original study, which shows X-rays of said horns. Crazy.

UPDATE: Reading the comments on the study itself, it seems like there’s some question as to the validity of the conclusion, that phone use is to blame. That said, there are a number of studies that do blame phone use for repetitive stress injuries to the neck. At the very least, we need more time and rigorous science to know what’s what.

UPDATE 2: This takedown by Ars Technica pulls no punches. It’s called Debunked: The absurd story about smartphones causing kids to sprout horns.