Biology

Biology is the science of life. It is concerned with the characteristics and behaviors of organisms, how species and individuals come into existence, and the interactions they have with each other and with their environment.

Contents

1 Overview of biology

1.1 Fields of study in biology
1.2 Related disciplines
1.3 People and history
1.4 List of topics

2 Evolution and biology

3 Classification of life

4 History of the word "biology"

5 See also

6 External links and resources

6.1 Links
6.2 Further reading

Overview of biology

Biology encompasses a broad spectrum of academic fields that are often viewed as independent disciplines. Together, they study life over a wide range of scales:

at the atomic and molecular scale, through molecular biology, biochemistry, and to some extent genetics
at the cellular scale, through cell biology
at the multicellular scales, through physiology, anatomy, and histology
at the level of the development or ontogeny of an individual organism, through developmental biology
at the level of heredity between parent and offspring through genetics
at the level of group behavior through ethology
at the level of an entire population, through population genetics
on the multi-species scale of lineages, through systematics
at the level of interdependent populations and their habitats through ecology and evolutionary biology
and speculatively through xenobiology at the level of life beyond the Earth.

Fields of study in biology

Aerobiology -- Anatomy -- Arachnology-- Astrobiology -- Biochemistry -- Bionics -- Biogeography -- Bioinformatics -- Biomechanics -- Biophysics-- Biotechnology -- Botany -- Cell biology -- Chorology -- Cladistics -- Crustaceology -- Cryptozoology -- Cycles -- Cytology -- Developmental biology -- Disease (Genetic diseases, Infectious diseases) -- Ecology (Theoretical ecology, Symbiology, Autecology, Synecology) -- Ethology -- Entomology -- Evolutionary biology (Evolution) -- Evolutionary developmental biology -- Freshwater biology -- Genetics (Population genetics, Quantitative genetics, Genomics, Proteomics) -- Herpetology -- Histology -- Human biology (Anthropology) -- Ichthyology -- Immunology -- Infectious diseases -- Pathology -- Epidemiology -- Limnology -- Malacology -- Mammalogy -- Marine biology -- Microbiology (Bacteriology) -- Molecular biology -- Morphology -- Mycology / Lichenology --- Myrmecology --- Neuroscience (Neuroanatomy, Neurophysiology, Systems neuroscience, Biological psychology, Psychiatry, Psychopharmacology, Behavioral science, Neuroethology, Psychophysics, Computational neuroscience, Cognitive neuroscience, Cognitive science)-- Oncology (the study of cancer) -- Ontogeny -- Origin of life -- Ornithology -- Paleontology (Paleobotany, Paleozoology)-- Parasitology -- Phycology (Algology) -- Phylogeny (Phylogenetics, Phylogeography) -- Physiology -- Phytopathology -- Reproductive biology --Structural biology -- Systems biology -- Taxonomy -- Toxicology (the study of poisons and pollution) -- Virology -- Xenobiology -- Zoology

Evolution and biology

One of the central, organizing concepts in biology is that all life has descended from a common origin through a process of evolution. Charles Darwin established evolution as a viable theory by articulating its driving force: natural selection. (Alfred Russell Wallace is commonly recognized as the co-discoverer of this concept). Genetic drift was embraced as an additional mechanism in the so-called modern synthesis. The evolutionary history of a species—which tells 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. Major events in the evolution of life, as biologists currently understand them, are summarized on this evolutionary timeline.

Classification of life

The classification of living things is called systematics, or taxonomy, and should reflect the evolutionary trees (phylogenetic trees) of the different organisms. Taxonomy piles up organisms in groups called taxa, while systematics seeks their relationships. The dominant system is called Linnaean taxonomy, which includes ranks and binomial nomenclature. How organisms are named is governed by international agreements such as the International Code of Botanical Nomenclature (ICBN), the International Code of Zoological Nomenclature (ICZN), and the International Code of Nomenclature of Bacteria (ICNB). A fourth Draft BioCode was published in 1997 in an attempt to standardize naming in the three areas, but it does not appear to have yet been formally adopted. The International Code of Virus Classification and Nomenclature (ICVCN) remains outside the BioCode.

Traditionally, living things were divided into five kingdoms:

Monera -- Protista -- Fungi -- Plantae -- Animalia

However, this five-kingdom system is now considered by many to be outdated. More modern alternatives generally begin with the three-domain system:

Archaea (originally Archaebacteria) -- Bacteria (originally Eubacteria) -- Eukaryota

These domains reflect whether cells have nuclei or not as well as differences in cell exteriors.

There is also a series of intracellular "parasites" that are progressively less alive in terms of being metabolically active:

Viruses -- Viroids -- Prions

History of the word "biology"

Formed by combining the Greek βίος (bios), meaning 'life', and λόγος (logos), meaning 'word', the word "biology" in its modern sense seems to have been introduced independently by Gottfried Reinhold Treviranus (Biologie oder Philosophie der lebenden Natur, 1802) and by Jean-Baptiste Lamarck (Hydrogéologie, 1802). The word itself is sometimes said to have been coined in 1800 by Karl Friedrich Burdach, but it appears in the title of Volume 3 of Michael Christoph Hanov's Philosophiae naturalis sive physicae dogmaticae: Geologia, biologia, phytologia generalis et dendrologia, published in 1766.