In a chilling prologue to the professional football season, the National Football League has agreed to pay $765 million to more than 4,500 retired players who claim long-term damage from the violent concussions that are part of the game.

The payment settles a pending lawsuit but hardly resolves the continuing threat to players from the traumatic hits - "bell ringers" in the sport's jargon - that mounting research shows are linked to brain disease in athletes' later years.

Autopsies have discovered degenerative damage from chronic traumatic encephalopathy in the brains of dozens of former football players. Safety changes in equipment and safer playing rules have been introduced, but fans of the multibillion-dollar NFL product still regularly see players stagger off the field after collisions.

Far more precaution and research is needed in the sport, not just on the professional level but down through the ranks to the powerful National Collegiate Athletic Association machine, which controls college ball, and to neighborhood leagues where 3 million children younger than 14 enthusiastically suit up for tackle football, mimicking the pros.

President Barack Obama, for all his love of sports, had to admit before the last Super Bowl: "I have to tell you, if I had a son, I'd have to think long and hard before I let him play football."

In settling the suits, the league did not formally admit culpability to the players' central charge that for years it had minimized the grave threats from concussions. But the payment is an overdue concession in the league's evolution in recognizing the sport's dangerous realities and taking more responsibility for the players' welfare beyond the game.