Professors tend to earn more as they become older. Woolley believes that professor’s contributions take a sharp turn downward after a certain point. If this is correct and professors retire at an increasingly older age, we have a problem.
What does the research says about this? We can look at published papers as a measure of productivity. A few decades ago, science professors were significantly less productive than younger colleagues, but this pattern has disappeared according to Kyvik and Olsen (Scientometrics, 2008):
In the humanities and the social sciences, productivity patterns by age have been relatively stable over the two decades. Increasing age does not seem to bring about lower levels of scientific and scholarly publishing. In the social sciences it is in fact staff over 60 years of age who are the most productive. (…) The largest changes have taken place in the natural sciences and technology. While staff over fifty years of age were significantly less productive than their colleagues aged between forty and fifty in the earliest period, in the latest period there were no such differences.
Gingras et al. (PLoS One, 2008) find that professors often remain productive until their retirement:
older professors who stay active in research keep their productivity at a high level until their retirement. We also found that the average scientific impact of professors decreases steadily from the beginning of their careers until about 50 years old, and then increases again.
It is true that professors’ salaries match their productivity, but that’s mostly because a small number of professors do most of the hard research and top-notch teaching, while the compensation plans tend to be much more egalitarians. There are also rather striking gaps between institutions which fail to reflect individual differences.
I don’t think we should be concerned with professors who choose to delay or avoid retirement. Retirement is often a bad deal for society. Our pension plans are often underwater.
Of course, we should urge people to contribute and to stay up-to-date. But that applies more broadly. You can be in your 40s and be out-of-touch.