Michael Berns, founding director of the Beckman Laser Institute and the Arnold and Mabel Beckman Professor at UC Irvine, is part of study in which his novel “laser tweezers” were employed to measure sperm cell motility. Berns and his colleagues at UC San Diego found that sperm cells from the more promiscuous chimpanzee and rhesus macaque species swim much faster and with much greater force than those of humans and gorillas, species where individual females mate primarily with only one male during a reproductive cycle. The reason? Rapidly swimming sperm cells would be evolutionarily favored when the mating pattern is polygamous, according to the researchers. For the study, Berns’ adjustable laser tweezers and sperm-tracking software allowed the team to precisely and accurately measure swimming force and speed of hundreds of individual sperm cells from males of the four primate species. The study appears in the Journal of the Royal Society Interface.