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- Billions of years ago, the only living things on Earth were single-celled organisms similar to bacteria. All forms of life evolved from these primitive ancestors. Over time, countless changes in the shape, size and function of various parts of the body gave rise to new forms of life—from ants to amoebas, hummingbirds to humans.
www.amnh.org/exhibitions/permanent/human-origins/understanding-our-past/how-evolution-worksHow Does Evolution Work? - American Museum of Natural History
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Sep 19, 2022 · Where did life on Earth begin? Two possibilities are in volcanically active hydrothermal environments on land and at sea. Some microorganisms thrive in the scalding, highly acidic hot springs environments like those found today in Iceland, Norway and Yellowstone National Park.
The Phanerozoic Eon (Greek: period of well-displayed life) marks the appearance in the fossil record of abundant, shell-forming and/or trace-making organisms. It is subdivided into three eras, the Paleozoic , Mesozoic and Cenozoic , with major mass extinctions at division points.
Prokaryotes were the earliest life forms, simple creatures that fed on carbon compounds that were accumulating in Earth’s early oceans. Slowly, other organisms evolved that used the Sun’s energy, along with compounds such as sulfides, to generate their own energy.
Oct 25, 2024 · Structures of communities of microorganisms, layered rocks called stromatolites, are found from more than three billion years ago. Since Earth is about 4.6 billion years old, these finds suggest that the origin of life must have occurred within a few hundred million years of that time.
- 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).
Jul 14, 2009 · The story of evolution spans over 3 billion years and shows how microscopic single-celled organisms transformed Earth and gave rise to complex organisms like animals. By Michael Marshall
Sep 1, 2009 · 13 min read. The Origin of Life on Earth. Fresh clues hint at how the first living organisms arose from inanimate matter. By Alonso Ricardo & Jack W. Szostak. September 2009 Issue. The Sciences....
