Life

Life (cf. biota) is a characteristic that distinguishes objects that have signaling and self-sustaining processes (i. e., living organisms) from those that do not,[1][2] either because such functionshave ceased (death), or else because they lack such functions and are classified as inanimate.[3][4] Biology is the science concerned with the study of life.

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 cancommunicate through various means.[1][5] A diverse array of living organisms (life forms) can be found in the biosphere on Earth, and the 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.

In philosophy and religion, the conception of life and itsnature varies. Both offer interpretations as to how life relates to existence and consciousness, and both touch on many related issues, including life stance, purpose, conception of a god or gods, a soulor an afterlife.

Materialism
Plant life
Herds of zebra and impala gathering on the Maasai Mara plain
An aerial photo of microbial mats around the Grand Prismatic Spring of Yellowstone NationalPark

Some of the earliest theories of life were materialist, holding that all that exists is matter, and that all life is merely a complex form or arrangement of matter. Empedocles (430 BC) arguedthat every thing in the universe is made up of a combination of four eternal "elements" or "roots of all": earth, water, air, and fire. All change is explained by the arrangement and rearrangement ofthese four elements. The various forms of life are caused by an appropriate mixture of elements. For example, growth in plants is explained by the natural downward movement of earth and the natural...