Life
Evidence suggest that life on Earth has existed for about 3.7 billion years. All known life forms share fundamental molecular mechanisms, and based on these observations, theories on the origin of life attempt to find a mechanism explaining the formation of a primordial single cell organism from which all life originates. There are many different hypotheses regarding the path that might have been taken from simple organic molecules via pre-cellular life to protocells and metabolism.
Although there is no universal agreement on the definition of life, scientists generally accept that the biological manifestation of life is characterized by organization, metabolism, growth, adaptation, response to stimuli and reproduction. Life may also be said to be simply the characteristic state of organisms. In biology, the science of living organisms, "life" is the condition which distinguishes active organisms from inorganic matter, including the capacity for growth, functional activity and the continual change preceding death.
A diverse array of living organisms (life forms) can be found in the biosphere on Earth, and properties common to these organisms—plants, animals, fungi, protists, archaea, and bacteria—are a carbon- and water-based cellular form with complex organization and heritable genetic information. Living organisms undergo metabolism, maintain homeostasis, possess a capacity to grow, respond to stimuli, reproduce and, through natural selection, adapt to their environment in successive generations. More complex living organisms can communicate through various means.
Read more about this topic: Natural Environment
Famous quotes containing the word life:
“In short, no association or alliance can be happy or stable without me. People can’t long tolerate a ruler, nor can a master his servant, a maid her mistress, a teacher his pupil, a friend his friend nor a wife her husband, a landlord his tenant, a soldier his comrade nor a party-goer his companion, unless they sometimes have illusions about each other, make use of flattery, and have the sense to turn a blind eye and sweeten life for themselves with the honey of folly.”
—Desiderius Erasmus (c. 1466–1536)
“The life of man is the true romance, which when it is valiantly conducted will yield the imagination a higher joy than any fiction.”
—Ralph Waldo Emerson (1803–1882)
“Art is only a means to life, to the life more abundant. It is not in itself the life more abundant. It merely points the way, something which is overlooked not only by the public, but very often by the artist himself. In becoming an end it defeats itself.”
—Henry Miller (1891–1980)