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The history of life on Earth traces the processes by which living and extinct organisms evolved, from the earliest emergence of life to the present day.
The timeline of the evolutionary history of life represents the current scientific theory outlining the major events during the development of life on planet Earth. Dates in this article are consensus estimates based on scientific evidence, mainly fossils.
Sep 19, 2022 · When did life on Earth begin? Earth is about 4.5 billion years old. Scientists think that by 4.3 billion years ago, Earth may have developed conditions suitable to support life. The oldest known fossils, however, are only 3.7 billion years old.
Aug 2, 2024 · Life ultimately is a material process that arose from a nonliving material system spontaneously—and at least once in the remote past. How life originated is discussed below. Yet no evidence for spontaneous generation now can be cited.
- Simple organic molecules were formed. Simple organic molecules, similar to the nucleotide shown below, are the building blocks of life and must have been involved in its origin.
- Replicating molecules evolved and began to undergo natural selection. All living things reproduce, copying their genetic material and passing it on to their offspring.
- Replicating molecules became enclosed within a cell membrane. The evolution of a membrane surrounding the genetic material provided two huge advantages: the products of the genetic material could be kept close by and the internal environment of this proto-cell could be different than the external environment.
- Some cells began to evolve modern metabolic processes and out-competed those with older forms of metabolism. Up until this point, life had probably relied on RNA for most jobs (as described in Step 2 above).
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Aug 1, 2017 · There was light. But then what happened? How did life arise on the third rocky planet orbiting the unremarkable star at the center of our solar system?
Oct 30, 2023 · HOW did life on Earth begin? Until 70 years ago, generations of scientists had failed to throw much light on biology’s murky beginnings. But then came three crucial findings in quick...
