WebApr 19, 2012 · For example, the first major life-form split — between the branch holding the ancestors of blue–green algae and most other bacteria and the branch that includes Archaea, the other major early ... WebEarth and the other planets in the solar system formed about 4.6 billion years ago. The early Earth was frequently hit with asteroids and comets. There were also frequent volcanic eruptions. Both were sources of water and gases for the atmosphere. The early Earth had no ozone layer, no free oxygen, and was very hot.

Geological history of oxygen - Wikipedia

WebUnderstanding the processes that lead to life, however, is complicated by the actions of biology itself. Earth’s atmosphere today bears little resemblance to the atmosphere of … WebUnderstanding the processes that lead to life, however, is complicated by the actions of biology itself. Earth’s atmosphere today bears little resemblance to the atmosphere of the early Earth, in which life developed; it has been nearly reconstituted by the bacteria, vegetation, and other life forms that have acted upon it over the eons. binding cover sheets

How did life begin and evolve on Earth, and has it evolved …

WebMay 14, 2016 · The findings contradict the decades-long belief that Earth's early atmosphere was thick and, if confirmed, would expand the list of the types of planets capable of supporting life, the researchers ... WebWhen Earth formed 4.6 billion years ago from a hot mix of gases and solids, it had almost no atmosphere. The surface was molten. As Earth cooled, an atmosphere formed mainly from gases spewed from volcanoes. It … WebThe history of life on Earth traces the processes by which living and fossil organisms evolved, from the earliest emergence of life to present day. Earth formed about 4.5 billion years ago (abbreviated as Ga, for gigaannum) and evidence suggests that life emerged prior to 3.7 Ga. Although there is some evidence of life as early as 4.1 to 4.28 Ga, it … binding covers a4 clear