Life

What is Life?

Life is a fundamental attribute of all living things that have the capacity to grow, change, interact with their environment, reproduce and adapt to meet their needs. It has fascinated philosophers, scientists, and theologians throughout history as they have pondered life's deepest meanings and origins. While there is no universal agreement on a definition, most consider life to encompass several key characteristics: organization, metabolism, mobility, responsiveness, growth, adaptation, reproduction and death as the cessation of these processes.

At its most basic level, life is a complex system of cellular and molecular processes that work synergistically to maintain an organism. Cells are the fundamental units of life—all living things are composed of one or more cells containing genetic material, energy producing systems and responsive feedback mechanisms. Cells carry out the chemical processes necessary for life like respiration, protein synthesis, transport and waste removal through the organized interplay of microscopic working parts like mitochondria, enzymes and membranes. This underlying molecular infrastructure gives rise to the high level properties we observe in complex multi-cellular organisms.

Life maintains an internal state far from thermodynamic equilibrium through metabolic pathways that process energy and materials from the environment. Living things are not static but rather dynamic, continually replenishing and rebuilding molecules to sustain vital functions. Metabolism also produces waste as byproducts that must be eliminated from the system. Movement of various kinds allows organisms to actively seek resources, mates and environments favorable for survival through locomotion, circulation or other methods. Life shows responsiveness through senses and information processing capabilities that allow it to perceive and respond to internal or external stimuli adaptively.

Growth and change over time are hallmarks of life as organisms increase in size and complexity through cellular division, differentiation and specialization from a single cell to fully formed complex structures. Life also demonstrates the ability to adapt and evolve in response to environmental pressures and changing conditions through genetic mutations and natural selection over generations. The ultimate expression and purpose of life appears to be reproduction—the propagation of genetically identical or analogous offspring to continue the lineage, sustain populations and drive evolution forward through inheritance of acquired traits. When metabolic, cellular and molecular processes cease functioning, life ends and death ensues.

At its core, life stems from complex chemical and physical relationships that spontaneously emerged and organized themselves on early Earth through principles of self-assembly and adaptation over eons of microscopic increments. While the exact origins of the first living things remain a mystery, we have observed self-replication and spontaneous organization in chemical systems under primordial conditions experimentally. The ultimate goal of life may simply be perpetuating itself through continuous regeneration, preserving and passing on genetic blueprints across generations despite obstacles or changes in the environment. From microbes to megafauna, life demonstrates the remarkable beauty, diversity and resilience that has flourished on our planet through billions of years of light and dark times.