Evolution of the offensive line

George Will's Newsweek column is about football this week -- specifically a discussion of changes in the sport since the days of the late "Bear" Bryant.

He gave some facts about change in player weight that surprised me:

Also in the 1960s, unlimited substitution began making huge players practical as offensive or defensive specialists. Barra notes that Bryant's 1966 team "looked like an average high school team today." It went 11-0 and then won the Sugar Bowl. It had only 14 players who weighed more than 200 pounds. The two heaviest weighed 213. The linemen averaged 195. The quarterback weighed 175.
Today, Scouts, Inc., reports that nearly 40 percent of the interior linemen who will go to Division I colleges in September 2006 -- many of these players not yet 18 -- already weigh at least 300 pounds. In 1980, only one NFL player topped 300. In 1994, the year a mortality study found that linemen have a 52 percent greater risk of dying from cardiovascular disease than the general population and that the largest players have six times the risk of cardiac death than normal-size players, the number of 300-pounders was 155. Ten years later 370 NFL players exceeded 300, and 10 exceeded 350.
This season, the offensive lines of 30 of the 32 NFL teams average at least 300 pounds, and one team averages 323. Of the 61 offensive college linemen invited to last February's NFL Scouting Combine, 58 weighed at least 300. Of the three little fellows, one weighed 299 and two weighed 298.

Of course, other players are getting bigger too -- even quarterbacks. But the change in offensive linemen is remarkable. An interesting case of a sudden shift in the conditions of existence, followed by gradual evolution to fill an new niche.