Range of Motion

Joy’s undergraduate thesis in anthropology was the basis for a study that she, PhD student Luke Fannin, professor Nathaniel Dominy, and professor Jeremy DeSilva published last week in the journal Royal Society Open Science. The study suggests that apes and early humans evolved with rotating shoulders and flexible elbows to facilitate safer “downclimbing” from trees. 

The research is attracting media attention from outlets including the New York Times and New Scientist.

According to the Times: “A key insight came from Mary Joy, a co-author of the study and at the time a Dartmouth undergraduate. She had been watching videos of chimpanzees, which are human’s closest living relatives, and sooty mangabeys, an Old World monkey native to West and Central Africa. The footage had been collected by two other authors of the study, Luke Fannin, a graduate student, and Jeremy DeSilva, a paleoanthropology professor at Dartmouth. Ms. Joy noticed that both animals climbed up trees with the same effort. The downward climb, however, was different.”

Joy’s undergraduate thesis, “Do Monkeys and Chimpanzees Climb the Same Way? A Kinematic Analysis of the Upper Limb During Vertical Climbing in a Wild Monkey (Cercocebus atys) and Ape (Pan troglodytes),” won the anthropology department’s Wesbrook Prize in 2021. She is currently a senior research specialist at Gartner.