Our colleague and friend Gerald Lincoln passed away on July 15, 2020, after a short illness. Gerald was a true biologist in the Darwinian tradition: he pursued his curiosity about diverse organisms both in the laboratory and at home on his farm north of Edinburgh. One of his earliest contributions was published anonymously when he used his beard shavings as a bioassay to record periodicity associated with his visits to the mainland from his field study site on the remote island of St. Kilda. Over subsequent decades, Gerald made outstanding contributions to our understanding of photoperiodism, seasonality, and circannual rhythms. His insightful and courageous scientific efforts, as well as his gentle good fellowship, will be sorely missed.