When a 2-year-old filly named Steinam came to Freestate Raceway in 1984 and paced a mile in 1:58 2/5, she was being hailed as one of the best of her age and sex that harness racing had ever seen. Two-year-old fillies of the past who were acknowledged all-time greats hadn't even been able to break the two-minute barrier on a five-eighths mile track.

Yet if Steinam had been born a few years later, and were entered in the $573,912 Breeders Crown at Freestate Saturday, she wouldn't be considered anything special. The probable favorite, So Cozy, has already paced a 1:56 4/5 mile at Freestate. At least a couple of the other fillies in the 15-horse lineup, Leah Almahurst and Marcasite, are nearly as fast.

Year after year, harness horses are getting faster and faster. The rate of improvement astonishes even the sport's insiders. "It's just amazing," said Stan Bergstein, executive vice president of the Harness Tracks of America. "Horses are doing things this year that were unheard-of five years ago, and nobody would have believed were possible 10 years ago."

The two-minute mile was universally considered the standard of excellence a decade ago. Now a 2:00 pacer or trotter can't even qualify to race in some places. The country's best pacers this year are capable of going in 1:51. Harness horses are rewriting history every year.

This rapid development of harness horses is a sharp contrast to the non-improvement of thoroughbreds. There is no evidence that thoroughbreds are any better today than they were 30 or 40 years ago. In 1950, the world record for one mile was 1:33 2/5. Today it is 1:32 1/5, and the difference is surely due more to faster tracks than faster horses.

Why are harness horses improving at such a dramatic rate? Experts cite faster tracks, more aggressive driving tactics, better training methods, more efficient sulkies. But the main reason that modern-day horses are pacing and trotting so much faster is that the industry is breeding better horses.

Because they are a much younger breed, standardbreds have a lot more room for improvement than thoroughbreds. But there is another key difference between the two industries. Thoroughbred racing forbids artifical insemination; harness racing permits it. If a truly prepotent stallion came along -- one capable of placing an indelible stamp on future generations -- he could have a much quicker, broader effect in harness racing than in thoroughbred racing.

Northern Dancer proved in the 1970s and 1980s that he was one of the greatest thoroughbred stallions, but he could still beget only about 40 offspring a year -- and they were staggeringly expensive. Northern Dancer's progeny dominated races like the Epsom Derby, there weren't enough of them to dominate the sport as a whole.

Meadow Skipper has been Northern Dancer's counterpart in the harness sport. He raced from 1962 to 1965, was considered one of the best pacers of his generation but not a superhorse and was retired to stud in 1966. He established himself as a sensational stud immediately -- the great Albatross and Most Happy Fella came from his first two crops -- and his semen impregnated about 140 mares a year until his death in 1982. Because his stud fee was low (never more than $25,000), just about anybody in the sport could afford to acquire Meadow Skipper blood, and just about everybody did.

"The result," said Tom Aronson of the American Horse Council, "was as if you had compressed 50 years of evolution into 10 years. The breed is now submerged in Meadow Skipper blood."

The stakes field at Freestate on Saturday illustrates the breadth and depth of his influence. Fifteen fillies are entered in the Breeders Crown, and all 15 are descendants of Meadow Skipper. Many have his blood on both the sire's and dam's side. The filly Same Set is by Ralph Hanover, whose sire was Meadow Skipper. Her dam is a daughter of Albatross, whose sire was also Meadow Skipper.

Some experts have worried that such close inbreeding could have bad effects on the species, but this hasn't happened. Some thoroughbred breeders (such as the late Federico Tesio) thought that artificial insemination would somehow rob a breed of its vitality. This, obviously, hasn't happened, either. In harness racing, all the cliches about "improving the breed" are a reality.