Celebrating Thomas van der Hammen’s 100th anniversary contributions of an explorer palynologist to neotropical paleoecology

We celebrate the 100^th anniversary of Thomas Van der Hammen (1924–2010). His career is a model of explorative environmental research in nearly all ecosystems of northern South America. He introduced palynological research into South America. As a PhD student he studied changes of climate, vegetation and landscape during the Lateglacial in Twente, eastern Netherlands. He continued his career in 1952 at the Geological Survey of Colombia with research, and teaching palynology and palaeobotany. He studied sediment archives from the Cretaceous to the Quaternary palynologically. He explored the potential of developing an understanding of the Quaternary history of neotropical ecosystems, the response to ice-ages in particular. In 1959 he returned to Leiden University where he succeeded professor Florschütz. In 1966 he was appointed at the University of Amsterdam and continued training Colombian and Dutch PhD students in studying the history of climate, flora and vegetation of northern South America, Amazonia and the Netherlands. He organised unparalleled transect studies through the Colombian Andes and collected a wealth of evidence in support of an elevational sequence of biodiversity. During decades Thomas skilfully used opportunities for research in academia as well as in industry. He gave structure for research at universities, municipalities, musea, ministries, and nature conservations. After his retirement he lived in Colombia. His country estate became a central meeting place where students, scientists, farmers, mayors, and even Ministers of State discussed the environmental past and future of Colombian ecosystems.