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In early pre-Cambrian times, the Earth was hot and volcanic, It was lashed by violent electrical storms and the atmosphere was rich in carbon dioxide, sulphur compounds and ozone. Conditions were ideal for chemical reactions to occur. Complex compounds began to form. Then inorganic molecules combined into even more complex organic compounds, gradually forming amino acids and proteins, the building blocks of life. Over millions of years, some of these compounds formed into simple cells, some of which had the capability to replicate themselves under certain conditions. Although not in any way aware of their surroundings, once cells began to replicate themselves, they had reached the point where life was possible.
About two and a half billion years ago, cells began to combine to form multiple-celled life forms. And life as we know it began to evolve from there.
Charles Darwin developed the Theory of Evolution by Natural Selection, after observing the evidence for evolution during his voyage in HMS Beagle. This theory says that species evolved over time in response to changes in the natural environment, and is seen by scientists as the best explanation for the facts. Darwin wrote Origin of Species in 1859 and The Descent of Man in 1871.
The English naturalist Alfred Russell Wallace also invented the theory of natural selection, independent of Charles Darwin. However, he believed that natural selection did not apply to humans, because our evolution was divinely guided. However, paleoanthropologists have found ample evidence that human evolution occured as the result of natural selection, just as the evolution of all other species did.
There are also numerous religious explanations, with most religions providing a theory for the origin of life. The Bible contains two accounts in Genesis, the first in verses 1:1 to 2:4a, and the second in verses 2:4b (from the second sentence of the verse) forward.
First answer by Dick Harfield. Last edit by Dick Harfield. Contributor trust: 152 [recommend contributor]. Question popularity: 6 [recommend question]
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