Others are not so sure. Dr. J. Worth Estes, a professor of pharmacology and a historian of science at the Boston University School of Medicine, was asked by Dr. Riddle to help evaluate the science behind the ancient medicines. He and Dr. Josiah C. Russell, a professor emeritus of medieval history at the University of New Mexico, are co-authors with Dr. Riddle of the Archeology paper, but do not share all Dr. Riddle's conclusions.

"We agreed to disagree," Dr. Estes said. "Do I believe in these things? There are the observations and they are tantalizing."

But, he added, "I sit here as a professor of pharmacology teaching about modern drugs to medical students." When we ask about the effectiveness of folk medicines, "we should apply the same standards," he said.

Dr. Estes said he studied medicines used in the 18th century to cure a variety of illnesses and found that most are ineffective. He said that he wondered why patients kept using medicines that did not work and that he reasoned that in most cases, people get better on their own no matter what they take, if they are healthy to begin with.

The same general philosophy guides his skepticism about the contraceptives and abortifacients used in ancient times. Most acts of intercourse do not lead to pregnancies, so without very careful studies, it can be hard to determine whether a substance prevented a pregnancy or whether there never would have been a pregnancy anyway. Likewise, many pregnancies naturally end in miscarriages, so it can be hard to tell whether a plant was responsible for a particular miscarriage. Other Factors to Consider

Other substances, Dr. Estes said, may be effective as contraceptives or abortifacients but they are toxic to other body tissues. "There are a lot of substances, like pennyroyal, that are well known and used by poor women in parts of Kentucky and other states," Dr. Estes said. "It helps cause abortions, but the problem is, it can knock out the liver."

Dr. Nutton suggested other limits on population growth. People often were malnourished, he pointed out, which limited fertility. They also are known to have used pessaries of all sorts. And sometimes, as in Sparta, men and women were physically separated. "The men were herded into barracks while the women were 20 miles away," Dr. Nutton said. And he said Sparta suffered severe population declines.