Sean G. Roberts, scientist at the Max Planck Institute for Psycholinguistics, Evolutionary Anthropology and Mathematics in the Sciences in Nijmegen, along with other researchers have looked at a total of 3,750 languages from different linguistic families. They were able to find a correlation between humidity and tone pitch. The humidity allows the mucous membranes in the larynx to remain moist, making them more elastic. Due to this there is a wider range of tone pitches in regions with a higher humidity, meanwhile, languages with a more simpler tone are commonly found in drier regions. This can serve to explain why tonal languages, found in the Tropics, Subtropical Asia and Central Africa, are rarer in dry areas, such as Central Europe. The findings demonstrate that climate is able to determine the development of languages.