Since the 1960s the national museum has grown and expanded to become a renowned multi-disciplinary research centre in both natural and cultural sciences, including Archeology, Paleontology, Mammalogy, Osteology and Education. The Department of Earth Sciences, for instance, now holds one of the largest collections of prehistoric remains related to human evolution in the world. It also hosts centres of scientific excellence, such as the East African Herbarium, the Centre for Biodiversity and the Institute of Primate Research. There are 15 regional museums throughout the country and eight historical and archaeological sites open to the public.