While Payne and his colleagues did not directly examine why large modern marine animals are at higher risk of extinction, their findings are consistent with a growing body of scientific literature that point to humans as the main culprits. "It is consistent with the tendency for fisheries to first exploit larger species and subsequently move down the food web and target smaller species," said study co-author Matthew Knope, a former postdoc in Payne's lab who is now an assistant professor of biology at the University of Hawai'i at Hilo.