Biology  

From The Art and Popular Culture Encyclopedia

Artforms of Nature (1904) by Ernst Haeckel
The 49th plate from Ernst Haeckel's Kunstformen der Natur of 1904, showing various sea anemones classified as Actiniae.

Fly, Caterpillar, Pear, and Centipede from the Mira Calligraphiae Monumenta by Joris Hoefnagel

The Bristlecone Pine can reach an age far greater than that of any other single living organism known, up to nearly 5,000 years.

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Biology (from Greek: βίος, bio, "life"; and λόγος, logos, "knowledge") is the study of life. It contains such topics as classifying the various forms of organisms, how species come into existence, and the interactions they have with each other and with the natural environment. Biology encompasses a broad spectrum of academic fields that are often viewed as independent disciplines. However, together they address phenomena related to living organisms (biological phenomena) over a wide range of disciplines, many of which, for example, botany, zoology, and medicine are considered ancient fields of study.

Evolution

A central organizing concept in biology is that life changes and develops through evolution and that all lifeforms known have a common origin (see Common descent). This has led to the striking similarity of units and processes discussed in the previous section. Introduced into the scientific lexicon by Jean-Baptiste de Lamarck in 1809,Charles Darwin established evolution fifty years later as a viable theory by articulating its driving force, natural selection (Alfred Russel Wallace is recognized as the co-discoverer of this concept as he helped research and experiment with the concept of evolution). 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.

The evolutionary history of the species— which describes the characteristics of the various species from which it descended— together with its genealogical relationship to every other species is called its phylogeny. Widely varied approaches to biology generate information about phylogeny. These include the comparisons of DNA sequences conducted within molecular biology or genomics, and comparisons of fossils or other records of ancient organisms in paleontology. Biologists organize and analyze evolutionary relationships through various methods, including phylogenetics, phenetics, and cladistics. For a summary of major events in the evolution of life as currently understood by biologists, see evolutionary timeline.

Up into the 19th century, it was commonly believed that life forms could appear spontaneously under certain conditions (see spontaneous generation). This misconception was challenged by William Harvey's diction that "all life [is] from [an] egg" (from the Latin "Omne vivum ex ovo"), a foundational concept of modern biology. It simply means that there is an unbroken continuity of life from its initial origin to the present time.

A group of organisms share a common descent if they share a common ancestor. All organisms on the Earth both living and extinct have been or are descended from a common ancestor or an ancestral gene pool. This last universal common ancestor of all organisms is believed to have appeared about 3.5 billion years ago. Biologists generally regard the universality of the genetic code as definitive evidence in favor of the theory of universal common descent (UCD) for all bacteria, archaea, and eukaryotes (see: origin of life).

Evolution does not always give rise to progressively more complex organisms. For example, the process of dysgenics has been observed among the human population.

See also

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