History of the Biosphere

Abstract

The emergence of the biosphere, marked by the first appearence of living organisms, occurred at an early stage of our planet’s history. The exact time when the biosphere came into being is difficult to determine because records of primitive living forms preserved in ancient sediments are indistinct and rare in the modern Earth’s crust. Due to recent progress in palaeontological studies it has been possible to increase the age of the earliest organisms from an estimated 2–3 billion years to 3.5–3.8 billion years. Since the possibility of finding evidence of more ancient organisms still remains, the dates given above refer to the lower boundary of the real age of the biosphere. However, from analysing the history of the formation of the Earth as a planet, we can suggest that the real age of the Earth’s biosphere cannot exceed the available estimates by very much.