There were constant references on ABC's telecast of the PGA Championship to the seniority and implied senility of Gene Littler, who is 47.

Littler was treated as some sort of contemporary of the dinosaur and was spoken of respectfully, as is done in countries in which ancestor worship is practiced.

But, if the Census Bureau is correct, one of every three adults in the United States is in his 60s. That means there are a lot of old-timers around, including sportswriters who will never see 47 again.

In harness racing, it used to be that nobody needed to apply as a driver unless he was at least 65. There were many great harness drivers over 70 and the fact that the average age is less now doesn't detract from the performances of the septuagenarians.

It takes considerable stamina to play tournament golf. Remember, the pros of the tour and in the major tournaments can't use carts. They walk.

Golf isn't exactly a sissy sport, despite the lack of physical contact. All sorts of back problems affect players, including Littler, Jerry Heard and Lee Trevino.

Jerry Pate has had a shoulder problem. John Mahaffey, who lost the U.S. Open in a playoff to Lou Graham in 1975 and was fourth in 1976, has been off the tour for months because of a wrist injury.

But the over-40 group hasn't done badly in pro sports. Julius Boros was 48 when he win the PGA title in 1968. Harry Vardon, one of the great names in golf, was 47 when he won his sixth British Open in 1914.

Old Tom Morris (as distinguished from his son, Tom Jr., who also was a champion) was 47 when he won his fourth British OPen.

Baseball has had its old folks, too. Remember the late Nick Altrock, who was a pitcher and coach for the Washington Senators? Altrock is in the record books as pitching two runless innings for Washington in 1924. He was 48 years old at the time. He was 43 when he quit as an active player in 1919.

Hoyt Wilhelm was 49 when he was still fooling them with his knuckleball, pitching for the Dodgers. Ty Cobb, Ted Williams and Walter Johnson were all well past 40 when they quit. The great Cy Young, who won 511 games, including 285 in the National League and 226 in the American League, was 44 before his rubber arm gave out.

Football has had its iron men, too. George Blanda was 49 when he finally was cut adrift by the Oakland Raiders. The great Jim Thorpe was playing football after he was 50 (and after he was out of the National Football League).

Sam Sneed remains the marvel at 65. Sneed, remember, made the cut in last week's PGA Championship when many golfers young enough to be his grandsons were eliminated.

Maybe Littler does look older than 47. He has had the troubles of Job with his frail body. His face looks like the parchment on which Thomas Jefferson wrote the first draft of the Declaration of Independence.

Old at 47? Don't tell that to the Congress. On Capitol Hill, you have to show your ID card when you're only 47. Anyway, Littler, the fragile antique, came very close to beating Lanny Wadkins, 20 years his junior, on that second hole of the PGA playoff. That's when Wadkins rolled in a long putt (variously estimated at 15 to 20 feet) to salvage a par. If Wadkins has missed that putt, would Littler have been too old?