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:
“What would life be without art? Science prolongs life. To consist of what—eating, drinking, and sleeping? What is the good of living longer if it is only a matter of satisfying the requirements that sustain life? All this is nothing without the charm of art.”
—Sarah Bernhardt (1845–1923)
“There is something else which has the power to awaken us to the truth. It is the works of writers of genius.... They give us, in the guise of fiction, something equivalent to the actual density of the real, that density which life offers us every day but which we are unable to grasp because we are amusing ourselves with lies.”
—Simone Weil (1909–1943)
“That way of life against which my generation rebelled had given us grim courage, fortitude, self-discipline, a sense of individual responsibility, and a capacity for relentless hard work.”
—Rose Wilder Lane (1886–1968)