Aaron Teixeira graduated from UC Berkeley in 2014, majoring in psychology, and is currently a research assistant in the Berkeley Cognitive Biology Lab. He is interested in the influences of individual personality and emotions on mammalian cooperative social structures and has recently completed his first study of the fox squirrel’s social dominance hierarchy, which he presented at the 2015 meeting of the Comparative Cognition Society. This study examined how squirrels communicate using tail-flagging signals and their relation to social dominance. He has also assisted in studies of cache-stealing, jumping, and tail-pitching biomechanics in squirrels. Just now Aaron is in the Kalahari desert in South Africa, where he studies the behavior and cognition of wild cape ground squirrels, assisting researchers from Cambridge and the University of Zurich.