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:
“To drift with every passion till my soul
Is a stringed lute on which all winds can play,
Is it for this that I have given away
Mine ancient wisdom, and austere control?
Methinks my life is a twice-written scroll
Scrawled over on some boyish holiday”
—Oscar Wilde (1854–1900)
“Each work of art excludes the world, concentrates attention on itself. For the time it is the only thing worth doing—to do just that; be it a sonnet, a statue, a landscape, an outline head of Caesar, or an oration. Presently we return to the sight of another that globes itself into a whole as did the first, for example, a beautiful garden; and nothing seems worth doing in life but laying out a garden.”
—Ralph Waldo Emerson (1803–1882)
“Hermann and Humbert are alike only in the sense that two dragons painted by the same artist at different periods of his life resemble each other. Both are neurotic scoundrels, yet there is a green lane in Paradise where Humbert is permitted to wander at dusk once a year; but Hell shall never parole Hermann.”
—Vladimir Nabokov (1899–1977)