The NFL is joining other sanctioning bodies in researching methods of preventing head injuries after studies revealed players have been suffering more frequent and more severe concussions in recent years. Onion Sports lists some sporting milestones in head safety:

1925: The facemask is added to leather football helmets as a response to the Decatur Staleys' unstoppable "punch in the face" defensive technique

1963: The NFL begins research on impact-resistant composite materials in an effort to devise a helmet that Mike Ditka will not eat

1967: After a rash of head injuries, the NHL increases required helmet thickness from 3/8 of an inch to 3/9 of an inch

1968: John Olerud born wearing batting helmet

1975: In a setback for safety in sports, Evel Knievel successfully campaigns in favor of injuries in general

1992: The NFL breathes a sigh of relief as it is discovered that Dennis Byrd of the New York Jets is paralyzed not by a preventable head injury but by a completely unpreventable spinal injury

1996: Baseball cringes as signs of head trauma become obvious in one of its star players when Atlanta Braves outfielder David Justice divorces Halle Berry

2001: Plagued by terrible ratings and low attendance, the XFL tries to figure out how to give more players concussions

2005: Following the tragic death of Dale Earnhardt, NASCAR mandates the use of full-face helmets after studies show they offer more advertising space