Sub-disciplines of biology are defined by the research methods employed and the kind of system studied:
theoretical biology uses mathematical methods to formulate quantitative models while
experimental biology performs empirical experiments to test the validity of proposed theories and understand the mechanisms underlying life and how it
appeared and
evolved from non-living matter about 4 billion years ago through a gradual increase in the complexity of the system.
[4][5][6] See
branches of biology.
The term
biology is derived from the
Greek word
βίος,
vios, "
life" and the suffix
-λογία,
-logia, "study of."
[7][8] The Latin-language form of the term first appeared in 1736 when Swedish scientist
Carl Linnaeus (Carl von Linné) used
biologi in his
Bibliotheca Botanica. It was used again in 1766 in a work entitled
Philosophiae naturalis sive physicae: tomus III, continens geologian, biologian, phytologian generalis, by
Michael Christoph Hanov, a disciple of
Christian Wolff. The first German use,
Biologie, was in a 1771 translation of Linnaeus' work. In 1797, Theodor Georg August Roose used the term in the preface of a book,
Grundzüge der Lehre van der Lebenskraft.
Karl Friedrich Burdach used the term in 1800 in a more restricted sense of the study of human beings from a morphological, physiological and psychological perspective (
Propädeutik zum Studien der gesammten Heilkunst). The term came into its modern usage with the six-volume treatise
Biologie, oder Philosophie der lebenden Natur (1802–22) by
Gottfried Reinhold Treviranus, who announced:
[9]- The objects of our research will be the different forms and manifestations of life, the conditions and laws under which these phenomena occur, and the causes through which they have been effected. The science that concerns itself with these objects we will indicate by the name biology [Biologie] or the doctrine of life [Lebenslehre].
Although modern biology is a relatively recent development, sciences related to and included within it have been studied since ancient times.
Natural philosophy was studied as early as the ancient civilizations of
Mesopotamia,
Egypt, the
Indian subcontinent, and
China. However, the origins of modern biology and its approach to the study of nature are most often traced back to
ancient Greece.
[10][11] While the formal study of
medicine dates back to
Pharaonic Egypt, it was
Aristotle (384–322 BC) who contributed most extensively to the development of biology. Especially important are his
History of Animals and other works where he showed naturalist leanings, and later more empirical works that focused on biological causation and the diversity of life. Aristotle's successor at the
Lyceum,
Theophrastus, wrote a series of books on
botanythat survived as the most important contribution of antiquity to the plant sciences, even into the
Middle Ages.
[12]
Scholars of the
medieval Islamic world who wrote on biology included
al-Jahiz (781–869),
Al-Dīnawarī (828–896), who wrote on botany,
[13] and
Rhazes (865–925) who wrote on
anatomy and
physiology.
Medicine was especially well studied by Islamic scholars working in Greek philosopher traditions, while natural history drew heavily on Aristotelian thought, especially in upholding a fixed hierarchy of life.
Advances in
microscopy also had a profound impact on biological thinking. In the early 19th century, a number of biologists pointed to the central importance of the
cell. Then, in 1838,
Schleiden and
Schwann began promoting the now universal ideas that (1) the basic unit of organisms is the cell and (2) that individual cells have all the characteristics of
life, although they opposed the idea that (3) all cells come from the division of other cells. Thanks to the work of
Robert Remak and
Rudolf Virchow, however, by the 1860s most biologists accepted all three tenets of what came to be known as
cell theory.
[15][16]
Serious evolutionary thinking originated with the works of
Jean-Baptiste Lamarck, who was the first to present a coherent theory of evolution.
[19] He posited that evolution was the result of environmental stress on properties of animals, meaning that the more frequently and rigorously an organ was used, the more complex and efficient it would become, thus adapting the animal to its environment. Lamarck believed that these acquired traits could then be passed on to the animal's offspring, who would further develop and perfect them.
[20] However, it was the British naturalist
Charles Darwin, combining the biogeographical approach of
Humboldt, the uniformitarian geology of
Lyell,
Malthus's writings on population growth, and his own morphological expertise and extensive natural observations, who forged a more successful evolutionary theory based on
natural selection; similar reasoning and evidence led
Alfred Russel Wallace to independently reach the same conclusions.
[21][22] Although it was the subject of
controversy (which continues to this day), Darwin's theory quickly spread through the scientific community and soon became a central axiom of the rapidly developing science of biology.
The discovery of the physical representation of heredity came along with evolutionary principles and
population genetics. In the 1940s and early 1950s, experiments pointed to
DNA as the component of
chromosomes that held the trait-carrying units that had become known as
genes. A focus on new kinds of model organisms such as
viruses and
bacteria, along with the discovery of the double-helical structure of DNA in 1953, marked the transition to the era of
molecular genetics. From the 1950s to the present times, biology has been vastly extended in the
molecular domain. The
genetic code was cracked by
Har Gobind Khorana,
Robert W. Holley and
Marshall Warren Nirenberg after DNA was understood to contain
codons. Finally, the
Human Genome Project was launched in 1990 with the goal of mapping the general human
genome. This project was essentially completed in 2003,
[23] with further analysis still being published. The Human Genome Project was the first step in a globalized effort to incorporate accumulated knowledge of biology into a functional, molecular definition of the human body and the bodies of other organisms.
