While Klemperer technically retired in 2002, he belongs to the subcategory of emeritus professors known as “research” professors who lead research groups and still hold office space. Klemperer led a freshman seminar on spectroscopy last year—which is offered again this spring—for which he offered tours of some of Harvard’s laboratories.

Klemperer, 76, says that while he was “concerned” at first about the law against mandatory retirement, he now believes the benefits of the law outweigh the problems.

Klemperer says that while there is a drop off in ground-breaking work after age 60, he feels he has been able to contribute to education and research even beyond those years.

Chair of the History department Akira Iriye agrees that many professors are capable of being productive researchers and excellent teachers past age 70.

“I have noticed that [some] people here who [do not] retire and continue to teach still do very well and they are popular teachers,” Iriye says, pointing to Warren Professor of American History Ernest R. May, who continues to lead sections for his Core class History A-80, “The Cold War.”

“Ernest May is an example of someone over 70 who is just so young still and so energetic in teaching. He is really quite ageless,” Iriye says.

A Moral Reasoning course taught by Buttenwieser University professor Stanley Hoffmann last year drew almost 300 students to its first meeting, and applications to his freshman seminar numbered near 100.

Porter University Professor Helen Vendler, who, at age 70, is the only female professor above the former retirement age, still attracts hundreds of applicants to her various poetry seminars.

Professor of Physics John Huth, who also chairs the department, suggests that professors who are involved in a broader variety of interests early in their careers tend to enjoy longer and more productive careers.

“One thing I’ve noticed is that the characters of people that tend to be productive after age 65 or 70 tend to be more eclectic types,” Huth says. “You can see that form from a younger age—professors with a more broad range of interests tend to have greater longevity.”

Almost 50 years at Harvard haven’t slowed Weatherhead University Professor Samuel Huntington, who received his Ph.D. from Harvard in 1948 and still teaches undergraduate lecture courses, writes books and serves as the chair of the Harvard Academy for International and Area Studies.

“When I was approaching 70, people told me that I should retire,” Huntington says. “But that feeling that one had a responsibility to retire seems to have faded. There has been a general shift of views about age in this country. People live longer, they stay healthier longer.”

Slowing Down

But not all professors are embracing the idea of an older faculty.

At age 73, Kenan Professor of Government Harvey C. Mansfield ’53 is a beneficiary of the 1986 amendment—he continues to teach lecture courses, advise students and write books. He still attends almost every Harvard football home game and Faculty meeting. Nonetheless, the contrarian professor, one of few outspoken conservatives on the Harvard campus, says he believes that professors ought to be forced to retire at a certain age.