Biology, also referred to as the biological sciences, is the study of living organisms utilizing the scientific method.
Biology examines the structure, function, growth, origin, evolution, and distribution of living things.
It classifies and describes organisms, their functions, how species come into existence, and the interactions they have with each other and with the natural environment.
Four unifying principles form the foundation of modern biology: cell theory, evolution, genetics and homeostasis.
Biology as a separate science was developed in the nineteenth century, as scientists discovered that organisms shared fundamental characteristics.
Biology is now a standard subject of instruction at schools and universities around the world, and over a million papers are published annually in a wide array of biology and medicine journals.
Most biological sciences are specialized disciplines.
Traditionally, they are grouped by the type of organism being studied: botany, the study of plants; zoology, the study of animals; and microbiology, the study of microorganisms.
The fields within biology are further divided based on the scale at which organisms are studied and the methods used to study them: biochemistry examines the fundamental chemistry of life; molecular biology studies the complex interactions of systems of biological molecules; cellular biology examines the basic building block of all life, the cell; physiology examines the physical and chemical functions of the tissues and organ systems of an organism; and ecology examines how various organisms interrelate.
Applied fields of biology such as medicine and genetic research involve many specialized sub-disciplines.
A central organizing concept in biology is that life changes and develops through evolution and that all lifeforms known have a common origin.
Charles Darwin established evolution as a viable theory by articulating its driving force, natural selection (Alfred Russel Wallace is recognized as the co-discoverer of this concept).
Darwin theorized that species and breeds developed through the processes of natural selection as well as by artificial selection or selective breeding.
Genetic drift was embraced as an additional mechanism of evolutionary development in the modern synthesis of the theory.
Biological form and function is created from and is passed on to the next generation by genes, which are the primary units of inheritance.
Physiological adaption to an organism's environment cannot be coded into its genes and cannot be inherited by its offspring.
Remarkably, widely different organisms, including bacteria, plants, animals, and fungi, all share the same basic machinery that copies and transcribes DNA into proteins.
For example, bacteria with inserted human DNA will correctly yield the corresponding human protein.