Over the past twenty years, the Qinghai-Tibet Plateau has seen different levels of grassland degradation. Li Li, an assistant professor from the Department of Health and Environmental Sciences at Xi'an Jiaotong-Liverpool University, has concluded that, contrary to the popular belief, pikas are not the cause of the problem; in fact, the size of their population merely indicates its scale. She suggests that further studies should be conducted to determine the real relationship among yaks, pikas and the grassland.