Which is more important for the richness of deep-sea animals, temperature or food? Dr. Moriaki Yasuhara from the School of Biological Sciences, the Research Division for Ecology & Biodiversity, and The Swire Institute of Marine Science, The University of Hong Kong (HKU), in collaborating with Hideyuki DOI from University of Hyogo and Masayuki USHIO from Kyoto University, have used long-term fossil datasets and a novel statistical method to detect causality and found that the answer is climate control of deep-sea biodiversity.