Structure of the Earth easily than does the upper mantle (chemical changes within the mantle may also be important). The viscosity of the mantle ranges between 10 and 10 Pa·s, depending on depth. In comparison, the viscosity of water is approximately 10 Pa·s and that of pitch is 10 Pa·s. The source of heat that drives plate tectonics is the primordial heat left over from the planet’s formation as well as the radioactive decay of uranium, thorium, and potassium in Earth’s crust and mantle. The average density of Earth is . Because the average density of surface material is only around , we must
The Social Conquest of Earth The Social Conquest of Earth The Social Conquest of Earth is a 2012 non-fiction book by biologist Edward O. Wilson. Wilson adapted the title of Paul Gauguin's famous mural as a theme -- "What are we?", "Where did we come from?", "Where are we going?"—for discussing his topic of eusocial behavior in several arthropod taxa and a few mammalian species, and its role in making humans as a species unique. Wilson argues, building on the paper "The evolution of eusociality" (2010) by Wilson, Martin Nowak and Corina Tarnita in "Nature", for more importance of group selection and against the idea