Barbara McClintock, 81, studies heredity in corn plants. She does so with a passionate intensity, working seven days a week, often 16 hours at a stretch. On the day last October when she won the Nobel Prize in medicine, studying her beloved maize was all she really wanted to do. But the phone kept ringing, reporters kept pestering. Finally the reclusive cytogeneticist—even the Nobel Prize committee has called her "a loner"—held a press conference in her Cold Spring Harbor, Long Island lab.

Yes, she said, the prize was a great honor. "But you don't need the public recognition," she added in a whisper. "You just need the respect of your colleagues."

She has had firsthand experience of that need for respect. In fact, when she first published the research that was to win her the Nobel, she was so far ahead of her peers, she recalled, that "they called me crazy. Absolutely mad."

At the time, the early '50s, scientists thought that chromosomes were like strands of pearls, with the genes—the basic units of heredity—fixed permanently in place. McClintock discovered that genes could actually "jump," changing their position and the way they functioned. This breakthrough was accomplished the old-fashioned way: patient crossbreeding and observation. The implications are vast. Jumping genes might play a role in a variety of diseases, including cancer.

The daughter of a physician, McClintock was born in Hartford, Conn. and raised mostly in Brooklyn and small towns in Massachusetts. She received her Ph.D. in botany from Cornell in 1927 and taught at various colleges until 1941, when she joined the Carnegie Institution's department of genetics in Cold Spring Harbor.

McClintock works alone and lives alone—she has never married—in an apartment that's a short walk from her laboratory. Apparently the late recognition of her work does not bother her. Of her Nobel she's said, "It might seem unfair to reward a person for having so much pleasure over the years."