Crust (geology) enriched compared to the underlying mantle. Although the continental crust comprises only about 0.6 weight percent of the silicate on Earth, it contains 20% to 70% of the incompatible elements. All the other constituents except water occur only in very small quantities and total less than 1%. Estimates of average density for the upper crust range between 2.69 and 2.74 g/cm and for lower crust between 3.0 and 3.25 g/cm. Earth formed approximately 4.6 billion years ago from a disk of dust and gas orbiting the newly formed Sun. It formed via accretion, where planetesimals and other smaller rocky bodies
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