 However, evidence of navicular degeneration has been established in the fossil record of early horses.Mary Thompson, a vertebrate paleontologist at Idaho Museum of Natural History, has found evidence in many species of early horses and concludes, "The results of this study strongly suggest that man’s intervention (whether by increased usage or improper breeding practices) may not be the sole cause of the syndrome", although she cautions that her results are preliminary.Working on steep hills, galloping, and jumping all contribute to navicular syndrome, as they place greater stress on the DDF tendons, and may cause overextension of the pastern and coffin joints.