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Evolution

Life is only known to exist on the planet Earth.(cf Astrobiology) The origin of life on Earth is not well understood, but it is known to have occurred at least 3.5 billion years ago, during the hadean or archean eons on a primordial Earth that had a substantially different environment than is found at present.These life forms possessed the basic traits of self-replication and inheritable traits. Once life had appeared, the process of evolution by natural selection resulted in the development of ever-more diverse life forms. Species that were unable to adapt to the changing environment and competition from other life forms became extinct. However, the fossil record retains evidence of many of these older species. Current fossil and DNA evidence shows that all existing species can trace a continual ancestry back to the first primitive life forms. The advent of photosynthesis in very basic forms of plant life worldwide allowed the sun's energy to be harvested to create conditions allowing for more complex life.[citation needed] The resultant oxygen accumulated in the atmosphere and gave rise to the ozone layer. The incorporation of smaller cells within larger ones resulted in the development of yet more complex cells called eukaryotes. Cells within colonies became increasingly specialized, resulting in true multicellular organisms. With the ozone layer absorbing harmful ultraviolet radiation, life colonized the surface of Earth.

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Nature

This article is about the physical universe. For other uses, see Nature (disambiguation).
"Natural" redirects here. For other uses, see Natural (disambiguation).

Bachalpsee in the Swiss Alps; generally mountainous areas are less affected by human activity
Much attention has been given to preserving the natural characteristics of Hopetoun Falls, Australia, while maintaining visitor access.
Lightning strikes during the eruption of the huge Galunggung volcano in 1982

Nature, in the broadest sense, is equivalent to the natural world, physical world, or material world.[citation needed] "Nature" refers to the phenomena of the physical world, and also to life in general. It ranges in scale from the subatomic to the cosmic.[citation needed]

The term "nature" may refer to living plants and animals, geological processes, weather, and physics, such as matter and energy. The term is often refers to the "natural environment" or wilderness—wild animals, rocks, forest, beaches, and in general areas that have not been substantially altered by humans, or which persist despite human intervention. For, example, manufactured objects and human interaction are generally not considered part of nature, unless qualified as, for example, "human nature" or "the whole of nature".[citation needed] This more traditional concept of "nature" implies a distinction between natural and artificial elements of the Earth, with the artificial as that which has been brought into being by a human consciousness or a human mind.