Zoologist, pioneer researcher in fertility, birth control

Samuel L. Leonard, a trailblazing researcher in the science of animal reproduction whose research more than 75 years ago has been described as a major step toward the modern sciences of fertility and birth control, has died. He was 101.

Family members said Leonard, a longtime professor at Cornell University, died Nov. 11 at a medical center in Ithaca, N.Y., after he was admitted with stomach pains.

A signal achievement credited to him was the finding that estrogen can prevent pregnancy. The study was performed on rats, but it was hailed as an important step in the development of the birth control pill.

In addition, he was credited with discovering that the pituitary gland produces two hormones, each governing an important step in ovulation and reproduction. In the 1930s, Leonard drove cross-country to present his findings at a meeting of a national scientific society, only to be told in no uncertain terms that he was in error.

But the discovery became widely accepted and used in enhancing and controlling fertility and the reproductive cycle.

In one of his more striking experiments with hormones, he enabled female canaries to sing. (The male canary is generally the musically gifted one.)

Friends described Leonard as a model of scientific, academic and personal accomplishment. By their accounts, he devoted the energies of an unusually long life to introducing undergraduates to zoology, being a mentor to graduate students, conducting research and setting examples of hard work and ethical behavior.

Many of Leonard’s research papers were published too early to be easily available on the Internet, where many scientists search for information. In addition, much of Leonard’s reputation rested with the memories of his graduate students, many of whom he outlived.

At Cornell, he conducted his research while teaching huge introductory classes. The Cornell Chronicle, a campus publication, said that by the time he retired in 1971, he had taught freshman zoology to 9,000 students.

To help himself juggle his responsibilities, Leonard adjusted the biological clocks of his laboratory rats, said former student Robert Foote, professor emeritus of physiology at Cornell. By illuminating their quarters at night, Leonard induced nocturnal behavior during the day, which enabled him to avoid working around the clock.

His research often entailed operating on animals. In a Cornell publication, another colleague hailed his surgical skill. “Sam Leonard can smoke a cigar, talk and perform a hypophysectomy on a rat at the same time,” said Ari Van Tienhoven, a professor emeritus of animal physiology, referring to the removal of the pituitary gland.

Samuel Leeson Leonard was born in Elizabeth, N.J., in 1905. He graduated from Rutgers University and obtained a doctorate in zoology from the University of Wisconsin in 1931. He was a faculty member at Union College in New York and at Rutgers before joining the zoology department at Cornell in 1941.

His wife, Olive Rees-Leonard, died in 1990. A son, David P. Leonard, died in 2004.

Besides his daughter, of Warwick, N.Y., survivors include four grandchildren and two great-grandsons.