R. Lawrence “Larry” Edwards
Gunn Professor and Distinguished McKnight University Professor, Department of Earth Sciences
Among three faculty members named Regents Professors—the highest faculty rank—in June 2015, Lawrence Edwards qualifies as the only genuine rock star.
Edwards is known worldwide for developing extremely precise methods for measuring the ages of rocks. For example, his "uranium-thorium" method detects incredibly small amounts of the elements uranium and thorium, data he uses to date rocks from caves in China and document climate change patterns in history.
By also measuring the proportions of different forms of oxygen, he can tell how much rain fell at the time the rock was deposited. Edwards and his research team have tracked the monsoons with great accuracy back 600,000 years, when Homo erectus, not Homo sapiens, inhabited the region.
In fact, he has used his dating methods to open a whole library of information about the last 600,000 years, a period dogged by a frustrating dearth of data.
“A series of ice ages, the most recent stages of evolution, and human history all happened then, as well as abrupt climate change,” says Edwards. “In a number of circumstances, [our methods] are better than the best carbon-14 dating, which is limited to dating materials from the last 40,000 years.”
For example, Edwards and his colleagues dated a rock containing a jawbone, found in a Chinese cave in 2007, at 100,000 years old, implying that modern humans made it across Asia far earlier than suspected. Because the remains also bore attributes of more primitive humans who were already in the area, the two groups could possibly have coexisted for some time, the way moderns and Neanderthals did in Europe.
A dedicated teacher and mentor, Edwards has trained numerous students and post-doctoral fellows who have gone on to successful careers, many as faculty members at respected institutions. One of the most cited earth scientists worldwide—ranking as high as second in recent years—he is a Fellow of the American Academy of Arts and Sciences and the National Academy of Sciences.