LIFE on Earth may have driven the evolution of the planet itself. The idea is that ancient microbes provided the chemical energy to create the Earth's continents - a nod to the Gaia hypothesis, in which life helps create the conditions it needs to survive.
The theory would solve the puzzle of why the Earth's continental crust appeared when it did, and explain the presence of granite, a substance not found anywhere else in our solar system.
The Earth formed 4.6 billion years ago, coalescing as a homogeneous mass that in time separated into the discrete layers we know today: the core, mantle and crust, plus oceans and atmosphere. However, during the first 600 to 800 million years of Earth's existence there were no stable continents. The oldest vestiges of continental crust, which date from the Archaean aeon about 4 billion years ago, are in Acasta in north-west Canada.
These rocks are made from granite or a similar material, which is unique to Earth. It is created when basalt rock melts and reforms, becoming enriched in silica, aluminium and certain metals as it reacts with compounds in water. Granitic rocks are less dense than basalt, so they rise to the surface, forming a stable continental crust.
Source:
http://www.newscientist.com/article/mg18925444.200-and-life-created-continents.html
