Understanding what sustains us and what sustains our world is fundamental. It is also the subject of the Global Food+ 2021, a joint webinar series run by researchers at Boston University, Harvard, MIT, and Tufts on their current work on the intersection of agriculture, health, environment, and society. This free online series, sponsored and hosted by Harvard’s Weatherhead Center for International Affairs, kicks off Friday and runs for four consecutive Fridays, with each event featuring 10 speed talks of seven minutes each. We spoke with Walter Willett, professor of epidemiology and nutrition at the T.H. Chan School of Public Health and Harvard Medical School professor of medicine, who will give a talk on “Fine Tuning Healthy, Sustainable Diets” during the inaugural session this week.