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:
“Our rural village life was a purifying, uplifting influence that fortified us against the later impacts of urbanization; Church and State, because they were separated and friendly, had spiritual and ethical standards that were mutually enriching; freedom and discipline, individualism and collectivity, nature and nurture in their interaction promised an ever stronger democracy. I have no illusions that those simpler, happier days can be resurrected.”
—Agnes E. Meyer (1887–1970)
“It is high time we realized that the havoc wrought in human life and ideals by a technological revolution and too long ignored has caught up with us.”
—Agnes E. Meyer (1887–1970)
“History not used is nothing, for all intellectual life is action, like practical life, and if you don’t use the stuff—well, it might as well be dead.”
—A.J. (Arnold Joseph)