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Population Density

Population density

Population density is a measurement of population per unit area or unit volume. It is frequently applied to living organisms, humans in particular.

Biological population densities

Population density is a common biological measurement and is often used by conservationists as a more appropriate measure than absolute numbers. Low population densities may cause an extinction vortex, where low densities lead to further reduced fertility. This is referred to as the Allee effect, named after W. C. Allee, who first identified it. Examples of this may include:
- Increased problems with locating mates in areas of low density.
- Increased inbreeding in areas of low population density.
- Increased susceptibility to catastrophic events in low population densities. Different species will have different expected densities. For example R-selected species commonly have high population densities, while K-selected species may have lower population densities. Low population densities may be associated with specialised mate location adaptations such as specialised pollinators; as found in the orchid family (Orchidaceae).

Human population density

For humans, population density is the number of persons per unit of area (which may include or exclude inland water), though it may also be expressed in relation to habitable, inhabited, productive (or potentially productive) or cultivated area. Commonly this may be calculated for a county, city, country, another territory, or the entire world.
- In the country articles in Wikipedia, the density is typically based on land area. However, the list of countries by population density is based on total area, including inland water. Several of the highest-density territories in the world are very small city-states, micronations or dependencies. These territories share a relatively small area and an exceptionally high urbanization level, with an economically specialized city population drawing also on rural resources outside the area, illustrating the difference between high population density and overpopulation. The most densely populated large state is Bangladesh, where 134 million people live in a highly agricultural area around the lower Ganges river, with a national population density in excess of 900 persons per square kilometre. The Indonesian island of Java has a similar density, with 114 million people, resulting in about 856 people per square kilometre. Overall world population density presently averages 42 people per square kilometre. Cities with exceptionally high population densities are often considered to be overpopulated, though the extent to which this is the case depends on factors like quality of housing and infrastructure or access to resources. Most of the largest densely-populated cities are in southern and eastern Asia, though Cairo and Lagos in Africa also fall into the category. City population is however, heavily dependent on the definition used for the urban area: densities will be far higher for the central municipality than when more recently-developed and as yet administratively unincorporated suburbs are included, as in the concepts of agglomeration or metropolitan area, the latter including sometimes neighbouring cities.

External links

- [http://www.demographia.com/db-citydenshist.htm Selected Current and Historic City, Ward & Neighborhood Densities]
- [http://antwrp.gsfc.nasa.gov/apod/ap030305.html Map over population density]
- [http://www.census.gov/population/documentation/twps0027/tab22.txt 1990 US Census list of top 100 cities by population, with population density] Category:Population als:Bevölkerungsdichte ja:人口密度 ko:인구 밀도 ms:Kepadatan th:ความหนาแน่นประชากร zh-min-nan:Jîn-kháu bi̍t-tō·

Population

] :For the use of the word population in statistics, see statistical population. In sociology and biology, a population is the collection of people, or organisms of a particular species, living in a given geographic area. In biology, plant and animal populations are studied, in particular, in a branch of ecology known as population biology, and in population genetics. In population dynamics, size, age and sex structure, mortality, reproductive behaviour, and growth of a population are studied. In biology, an isolated population denotes a breeding group whose members breed mostly or solely among themselves, usually as a result of physical isolation, although biologically they could breed with any members of the species. Meta-population is a group of sub-populations in a given area, where the individuals of the various sub-populations are able to cross uninhabitable areas of the region. Biological dispersal is one of the key elements affecting in such populations. Demography is the study of human populations. Various aspects of human behavior in populations are studied in sociology, economics, and geography. Study of populations is almost always governed by the laws of probability, and the conclusions of the studies may thus not always be applicable to some individuals. This odd factor may be reduced by statistical means, but such a generalization may be too vague to imply anything. Demography is used extensively in marketing, which relates to economic units, such as retailers, to potential customers. For example, Starbucks, a coffee shop company that wants to sell to a younger audience, looks at the demographics of an area to be able to appeal to this younger audience.

Population density

coffee Population density is measured by dividing the number of individuals by the area of the region in which they live. Some observers of human societies believe that the concept of carrying capacity also applies to the human population of the Earth, and that unchecked population growth can result in a "Malthusian catastrophe." Others dispute this view. The graph to the right depicts logistic growth of population. Populate, as a verb, means the process of populating a geographic area, as by procreation or immigration. The countries with the highest population density are microstates: Monaco, Singapore, the Vatican City, and Malta. Among larger-sized countries, Japan has one of the highest population densities.

Population pyramid

Japan The age and gender distribution of a population within a given nation or region is commonly represented by means of a population pyramid. This is a triangular distribution with the portion of the population along the horizontal X-axis and the 5-year age grouping along the vertical Y-axis. Male population is shown to the left of the vertical axis and female to the right. This type of chart displays the development of a population over a period of time. Nations with low infant mortality and high longevity will display a more rectangular shape as a majority of the population living to old age. The converse will have a more pyramidal shape with a wide base, reflecting higher infant mortality and greater risk of early death.

Underpopulation

In biology, a rarely occurring situation in which a group of individuals of a species appear in a new, inhabitable area suitable for more individuals, and begin to populate it. This may also happen if individuals of a species have been transferred to new areas on purpose or by accident. Ecological niches are usually populated, but evolution of a species may enable it to overcome the difficulties encountered in an initially hostile environment.

Overpopulation

evolution The world's human population is currently growing by more than 75 million people per year. About half the world lives in nations with sub-replacement fertility, and population growth in those countries is due to immigration. Overpopulation can result from increases in births and survival rates, or from an unsustainable use and depletion of resources. Advances in technology can reduce the threat of overpopulation by making new resources available, or by increasing the productivity of existing resources. In biology, a classic example of an overpopulation are the lemmings in Lapland, which procreate over the years to such densities, that a great part of the population is forced to wander to inhospitable areas. Nowadays, this happens usually in less dramatic ways than in the past, one reason probably being that the food supply of lemmings is shared with an increased number of reindeer in Lapland.

Population control

Population control is the practice of curtailing population increase, usually by reducing the birth rate. Surviving records from Ancient Greece document the first known examples of population control. These include the colonization movement, which saw Greek outposts being built across the Mediterranean and Black Sea basins to accommodate the excess population of individual states. An important example of mandated population control is China's one-child policy, in which having more than one child is made extremely unattractive. This has led to allegations that practices like infanticide, forced abortions, and forced sterilization are used as a result of the policy. In ecology, population control is on occasions considered to be done solely by predators, diseases, parasites, and environmental factors, though at many times human effects on animal and plant populations are also considered. Migrations of animals may be seen as a natural way of population control, for the food on land is more abundant on some seasons. The area of the migrations' start is left to reproduce the food supply for large mass of animals next time around. See also immigration.

Population decline

Population decline is a fall in a region's population. It can be caused by sub-replacement fertility or heavy emigration, or more dramatically disease, famine, or war. Or most often by a combination of the factors. In the past population decline was mostly observed due to disease. In recent years, the population of Russia and seventeen other ex-Communist countries has begun to decline (1995-2005). The Black Death in Europe, the arrival of Old World diseases to the Americas, or the Irish Potato Famine (1845-1849), all caused massive population declines. In biology, population decline of a species is usually described as a result of gradually worsening environmental factors, such as prolonged drought or loss of inhabitable areas for the studied species.

Population ageing

Population ageing occurs when the fertility rate declines. This means that, for a period of time, the ratio of old to young will be higher than average. It also occurs due to increasing life expectancy. Japan and Western Europe are the two regions which are most confronted by severe population ageing in the near future. The second largest expenditure of most governments is education and these expenses will fall with an ageing population. However older people tend to be the section of the population most concerned about crime and most insistent on more (and more expensive) law and order.

Population transfer

biological aspects, see introduced species Population transfer is a term referring to a policy by which a state forces the movement of a large group of people out of a region, most frequently on the basis of their ethnicity or religion. This has occured in India and Pakistan, between Turkey and Greece, and in Eastern Europe after the Second World War. Other movements in population are caused by immigration, such as the immigration from Europe to European colonies in the Americas, Africa, Australia and other places.

Population bomb

A best-selling work, The Population Bomb (1968) by Paul R. Ehrlich predicted disaster for humanity due to overpopulation and the "population explosion". A "population bomb," as defined in the book, requires three things: a rapid rate of change; a limit of some sort; and delays in perceiving the limit. The book's specific prediction that "in the 1970s and 1980s hundreds of millions of people will starve to death" did not come to pass, however, due for the most part to the efforts of Norman Borlaug's "Green Revolution" of the 1960s. It was later shown by Keith Greiner (1994) that Ehrlich's projections could not possibly have held the scrutiny of time, because Ehrlich applied the financial compound interest formula to population growth. Using two sets of assumptions based on Ehrlich's hypothesis, it was shown that the theorized wild growth in population and subsequent scarcity of resources could not have occurred on Ehrlich's time schedule.

World population

According to estimates published by the United States Census Bureau, the world population at the beginning of December 2005 was about 6,483,600,000. The United Nations Population Fund designated October 12, 1999 as the approximate day on which world population reached six billion. This was about 12 years after world population reached five billion, in 1987.

Countries by population

About 4 billion of the world's nearly 6.5 billion people live in Asia. Seven of the world's ten largest countries by population are in Asia(although Russia is also located in Europe). However, a large population is not the same thing as economic size, and the United States, which has a much smaller population than India or China, has a much larger economy.

External links

- Phishare.org (2005). [http://www.phishare.org Population and Health InfoShare]. Retrieved February 13, 2005.
- [http://www.prb.org Population Reference Bureau] (2005). Retrieved February 13, 2005.
- Populationworld.com (2005). [http://www.populationworld.com/ Population World: Population of World]. Retrieved February 13, 2004.
- United Nations (2004). [http://www.un.org/esa/population/ Population Division], Department of Economic and Social Affairs. Retrieved February 13, 2004.
- United States Census Bureau (2005). [http://www.census.gov/cgi-bin/ipc/idbrank.pl Census Bureau - Countries Ranked by Population]. Retrieved February 13, 2005.
- PopulationData.net (2005). [http://www.populationdata.net PopulationData.net - Informations and maps about populations around the world]. Retrieved March 4, 2005.
- World Population Clock (French) [http://www.worldpopclock.com WorldPopClock.com - World population clock].
- [http://www.census.gov/ipc/www/popclockworld.html World Population Clock (English) - US Census] Category:Ecology Category:Sociology Category:Population zh-min-nan:Jîn-kháu ko:인구 ja:人口 simple:Population th:ประชากร

Human

Humans or human beings define themselves in biological, social, and spiritual terms. Biologically, humans are classified as the species Homo sapiens (Latin for "wise man" or "thinking man"): a bipedal primate of the superfamily Hominoidea, together with the other apes: chimpanzees, gorillas, orangutans, and gibbons. Humans have an erect body carriage that frees their upper limbs for manipulating objects and a highly developed brain capable of abstract reasoning, speech, language, and introspection. Bipedal locomotion appears to have evolved before the development of a large brain. The origins of bipedal locomotion and of its role in the evolution of the human brain are topics of ongoing research. The human mind has several distinct attributes. It is responsible for complex behaviour, especially language. Curiosity and observation have led to a variety of explanations for consciousness and the relation between mind and body. Psychology attempts to study behaviour from a scientific point of view. Religious perspectives emphasise a soul, qi or atman as the essence of being, and are often characterised by the belief in and worship of God, gods, spirits, or other people. Philosophy, especially philosophy of mind, attempts to fathom the depths of each of these perspectives. Art, music and literature are often used in expressing these concepts and feelings. Like all primates, humans are inherently social. They create complex social structures composed of co-operating and competing groups. These range from nations and states down to families. Seeking to understand and manipulate the world around them has led to the development of technology and science. Artifacts, beliefs, myths, rituals, values, and social norms have all helped to form humanity's culture.

Terminology

In general, the word "people" is a collective or plural term for any specific group of individual persons. However, when used to refer to a group of humans possessing a common ethnic, cultural or national unitary characteristic or identity, "people" is a singular count noun, and as such takes an "s" in the plural (examples: "the English-speaking peoples of the world", "the indigenous peoples of Brazil"). ethnic Juvenile males are called boys, adult males men, juvenile females girls, and adult females women. Humans are commonly referred to as persons or people, and collectively as Man (capital M), mankind, humankind, humanity, or the human race. Until the 20th century, "human" was only used adjectivally ("pertaining to mankind"). Nominal use of "human" (plural "humans") is short for "human being", and not considered good style in traditional English grammar. As an adjective, "human" is used neutrally (as in "human race"), but "human" and especially "humane" may also emphasise positive aspects of human nature, and can be synonymous with "benevolent" (versus "inhumane"; cf. humanitarian). A distinction is maintained in philosophy and law between the notions "human being", or "man", and "person". The former refers to the species, while the latter refers to a rational agent (see, for example, John Locke's Essay concerning Human Understanding II 27 and Immanuel Kant's Introduction to the Metaphysic of Morals). The term "person" is thus used of non-human animals, and could be used of a mythical being, an artificial intelligence, or an extraterrestrial. An important question in theology and the philosophy of religion concerns whether God is a person. In Latin, "humanus" is the adjectival form of the noun "homo", translated as "man" (to include males and females). The Old English word "man" could also have this generic meaning, as demonstrated by such compounds as "wifman" ("female person") → "wiman" → "woman". For the etymology of "man" see mannaz.

Biology

Anatomy and physiology

mannaz] Humans exhibit fully bipedal locomotion. This leaves the forelimbs available for manipulating objects using opposable thumbs. Humans vary substantially around the mean height and mean weight. Some of this variation is explained by locality and historical factors. Although body size is largely determined by genes, it is also significantly influenced by diet and exercise. The mean height of a North American adult female is 162 centimetres (5 feet 4 inches) and the mean weight is 62 kilograms (137 pounds). North American adult males are typically larger: 175 centimetres (5 feet 9 inches) and 78 kilograms (172 pounds). Human skin appears to be relatively hairless in comparison to other primates; however, most humans have a larger number of hairs on their body than a chimpanzee. The main difference is that human hairs are shorter, finer, and less coloured then the average chimpanzee's, thus rendering them harder to see. The colour of human hair and skin is determined by the presence of coloured pigments called melanins. Most researchers believe that skin darkening was an adaptation that evolved as a defence against UV solar radiation; melanin is an effective sunblock. The skin colour of contemporary humans can range from very dark brown to very pale pink. It is geographically stratified and in general correlates with the environmental level of UV. Human skin and hair colour is controlled in part by the MC1R gene. For example, the red hair and pale skin of some Europeans is the result of mutations in MC1R. Human skin has a capacity to darken (sun tanning) in response to UV exposure. Variation in the ability to sun tan is also controlled in part by MC1R. sun tanning] Because humans are bipedal, the pelvic region and spinal column tend to become worn, creating locomotion difficulties in old age. The individual need for regular intake of food and drink is prominently reflected in human culture, and has led to the development of food science. Failure to obtain food leads to hunger and eventually starvation, while failure to obtain water leads to dehydration and thirst. Both starvation and dehydration cause death if not alleviated. In modern times, obesity amongst humans has increased to almost epidemic proportions, leading to health complications and increased mortality in some developed countries, and is becoming problematic elsewhere. The average sleep requirement is between seven and eight hours a day for an adult and nine to ten hours for a child. Elderly people usually sleep for six to seven hours. It is common, however, in modern societies for people to get less sleep than they need, leading to a state of sleep deprivation. The human body is subject to an ageing process and to illness. Medicine is the science that explores methods of preserving bodily health.

Life cycle

health] The human life cycle is similar to that of other placental mammals. New human life develops from conception. An egg is usually fertilised inside the female by sperm from the male through sexual intercourse, though in vitro fertilisation methods are also used. The fertilised egg is called a zygote. The zygote divides inside the female's uterus to become an embryo which over a period of thirty-eight weeks becomes the fetus. At birth, the fully grown fetus is expelled from the female's body and breathes independently as a baby for the first time. At this point, most modern cultures recognise the baby as a person entitled to the full protection of the law, though some jurisdictions extend personhood to human fetuses while they remain in the uterus. Compared with that of other species, human childbirth is relatively complicated. Painful labours lasting twenty-four hours or more are not uncommon, and may result in injury to the child or the death of the mother, although the chances of a successful labour increased significantly during the twentieth century in wealthier countries. Natural childbirth remains an arguably more dangerous ordeal in remote, underdeveloped regions of the world, though the women who live in these regions have argued that their natural childbirth methods are safer and less traumatic for mother and child. Natural childbirth Human children are born after a nine-month gestation period, with typically 3–4 kilograms (6–9 pounds) in weight and 50–60 centimetres (20–24 inches) in height in developed countries. [http://www.childinfo.org/eddb/lbw] Helpless at birth, they continue to grow for some years, typically reaching sexual maturity at twelve to fifteen years of age. Boys continue growing for some time after this, reaching their maximum height around the age of eighteen. These values vary too, depending on genes and environment. The human lifespan can be split into a number of stages: infancy, childhood, adolescence, young adulthood, maturity and old age, though the lengths of these stages, especially the later ones, are not fixed. There are striking differences in life expectancy around the world. The developed world is quickly getting older, with the median age around 40 years (highest in Monaco at 45.1 years), while in the developing world, the median age is 15–20 years (the lowest in Uganda at 14.8 years). Life expectancy at birth is 77.2 years in the U.S. as of 2001. [http://www.cdc.gov/nchs/fastats/lifexpec.htm] The expected life span at birth in Singapore is 84.29 years for a female and 78.96 years for a male, while in Botswana, due largely to AIDS, it is 30.99 years for a male and 30.53 years for a female. One in five Europeans, but one in twenty Africans, is 60 years or older, according to The World Factbook. [http://www.cia.gov/cia/publications/factbook] African.]] The number of centenarians in the world was estimated by the United Nations [http://www.un.org/ageing/note5713.doc.htm] at 210,000 in 2002. The maximum life span for humans is thought to be over 120 years. Worldwide, there are 81 men aged 60 or over for every 100 women, and among the oldest, there are 53 men for every 100 women. The philosophical questions of when human personhood begins and whether it persists after death are the subject of considerable debate. The prospect of death may cause unease or fear. People who are near death sometimes have a near-death experience, in which they have visions. Burial ceremonies are characteristic of human societies, often inspired by beliefs in an afterlife. Institutions of inheritance or ancestor worship may extend an individual's presence beyond his physical lifespan (see immortality).

Genetics

Humans are a eukaryotic species. Each diploid cell has two sets of 23 chromosomes, each set received from one parent. There are 22 pairs of autosomes and one pair of sex chromosomes. At present estimate, humans have approximately 20,000–25,000 genes and share 95% of their DNA with their closest living evolutionary relatives, the two species of chimpanzees. [http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=pubmed&dopt=Abstract&list_uids=12368483] Like other mammals, humans have an XY sex determination system, so that females have the sex chromosomes XX and males have XY. The X chromosome is larger and carries many genes not on the Y chromosome, which means that recessive diseases associated with X-linked genes affect men more often than women. For example, genes that control the clotting of blood reside on the X chromosome. Women have a blood-clotting gene on each X chromosome so that one normal blood-clotting gene can compensate for a flaw in the gene on the other X chromosome. But men are hemizygous for the blood-clotting gene, since there is no gene on the Y chromosome to control blood clotting. As a result, men will suffer from haemophilia more often than women.

Race and ethnicity

haemophilia, Black, White (Hispanic), and Asian. Top row males, bottom row females.]] Humans often categorise themselves and others in terms of race or ethnicity. In the United States, racial categories are primarily based on language and ethnicity, although biological qualities, such as skin colour, blood type, facial features, ancestry, and other genetic variances are also key factors. Self identification with an ethnic group is usually based on kinship and descent, as well as presumed advantage. When race and ethnicity lead to variant treatment it is thought to impact social identity, giving rise to the theory of identity politics. Although most humans recognise that variances occur within a species, it is often a point of dispute as to what these differences entail, and if discrimination based on race (racism) is acceptable in the early twenty-first century. Race and intelligence, scientific racism, xenophobia and ethnocentrism are just a few of the many basis' for such practices.

Habitat

The view most widely accepted by the anthropological community is that the human species originated in the African savanna between 100 and 200 thousand years BCE, colonised the rest of the Old World and Oceania by 40,000 years BCE, and finally colonised the Americas by 10,000 years BCE. Homo sapiens displaced groups such as Neanderthals and Homo floresiensis through more successful reproduction and competition for resources, and/or extermination. (See Human evolution, Vagina gentium, and Environment of Evolutionary Adaptedness.) Technology has allowed humans to colonise all of the continents and adapt to all climates. Within the last few decades, humans have been able to explore Antarctica, the ocean depths, and space, although long-term habitation of these environments are not yet possible. Humans, with a population of about six thousand million, are one of the most numerous mammals on Earth. Most humans (61%) live in the Asian region. The vast majority of the remainder live in the Americas (14%), Africa (13%) and Europe (12%), with 5% in Oceania. (See list of countries by population and list of countries by population density.) list of countries by population density (The arctic is at the centre of the map and the numbers are millennia before present).]] The original human lifestyle is hunting-gathering, which is adapted to the savanna. Other human lifestyles are nomadism (often linked to animal herding) and permanent settlements made possible by the development of agriculture. Humans have a great capacity for altering their habitats by various methods, such as agriculture, irrigation, urban planning, construction, transport, and manufacturing goods. Permanent human settlements are dependent on proximity to water and, depending on the lifestyle, other natural resources such as fertile land for growing crops and grazing livestock, or seasonally by populations of prey. With the advent of large-scale trade and transport infrastructure, immediate proximity to these resources has become unnecessary, and in many places these factors are no longer the driving force behind growth and decline of population. Human habitation within closed ecological systems in hostile environments (Antarctica, outer space) is expensive, typically limited in duration, and restricted to scientific, military, or industrial expeditions. Life in space has been very sporadic, with a maximum of thirteen humans in space at any given time, starting with Yuri Gagarin's space flight in 1961. Between 1969 and 1974, up to two humans at a time spent brief intervals on the Moon. As of 2005, no other celestial body has been visited by human beings, although there has been a continuous human presence in space since the launch of the initial crew to inhabit the International Space Station on October 31, 2000.

Population

2000 From 1800 to 2000, the human population increased from one to six billion. It is expected to crest at around ten billion during the 21st century. In 2004, around 2.5 billion out of 6.3 billion people lived in urban centres, and this is expected to rise during the 21st century. Problems for humans living in cities include various forms of pollution, crime, and poverty, especially in inner city and suburban slums. Geneticists Lynn Jorde and Henry Harpending of the University of Utah have concluded that the variation in the total stock of human DNA is minute compared to that of other species; and that around 74,000 years ago, human population was reduced to a small number of breeding pairs, possibly as small as 1000, resulting in a very small residual gene pool. Various reasons for this bottleneck have been postulated, the most popular, called the Toba catastrophe theory, being the eruption of a volcano at Lake Toba.

Human evolution

The study of human evolution encompasses many scientific disciplines, but most notably physical anthropology and genetics. The term "human", in the context of human evolution, refers to the genus Homo, but studies of human evolution usually include other hominids and hominines, such as the australopithecines. Biologically, humans are defined as hominids of the species Homo sapiens, of which the only extant subspecies is Homo sapiens sapiens (Latin for "very wise man"); Homo sapiens idaltu (roughly translated as "elderly wise man") is the extinct subspecies. Modern humans are usually considered the only surviving species in the genus Homo, although some argue that the two species of chimpanzees should be reclassified from Pan troglodytes (Common Chimpanzee) and Pan paniscus (Bonobo/Pygmy Chimpanzee) to Homo troglodytes and Homo paniscus respectively, given that they share a recent ancestor with man. [http://news.nationalgeographic.com/news/2003/05/0520_030520_chimpanzees.html] Full genome sequencing resulted in these conclusions: "After 6 [million] years of separate evolution, the differences between chimp and human are just 10 times greater than those between two unrelated people and 10 times less than those between rats and mice." [http://news.ft.com/cms/s/43445728-1a44-11da-b279-00000e2511c8.html Chimp and human DNA is 96% identical] It has been estimated that the human lineage diverged from that of chimpanzees about five million years ago, and from gorillas about eight million years ago. However, in 2001 a hominine skull approximately seven million years old, classified as Sahelanthropus tchadensis, was discovered in Chad and seems to indicate an earlier divergence. Two prominent scientific theories of the origins of contemporary humans exist. They concern the relationship between modern humans and other hominids: The single-origin or "out of Africa" hypothesis proposes that modern humans evolved in Africa and later replaced hominids in other parts of the world. The multiregional hypothesis proposes that modern humans evolved at least in part from independent hominid populations. Human evolution is characterised by a number of important physiological trends:
- expansion of the brain cavity and brain itself, which is typically 1,400 cm³ in volume, over twice that of a chimpanzee or gorilla. The pattern of human postnatal brain growth differs from that of other apes (heterochrony), allowing for an extended period of social learning in juvenile humans. Physical anthropologists argue that a reorganisation of the structure of the brain is more important than cranial expansion itself;
- canine tooth reduction;
- bipedal locomotion;
- descent of the larynx, which makes speech possible. Humans are classified as Homo sapiens sapiens. A camp of physical anthropologists see neanderthalensis as a subspecies and classify the neanderthals as Homo sapiens neanderthalensis. A second camp of physical anthropologists see the neanderthals as a distinct species diverging from the modern human lineage over 500,000 years ago. Under this classification, neaderthals are Homo neanderthalensis. Recent DNA analysis suggests that neanderthalensis were not a subspecies. How these trends are related and what their role is in the evolution of complex social organisation and culture are matters of ongoing debate. larynx]]

Intelligence

Most humans consider their species to be the most intelligent in the animal kingdom. Certainly, humans are the only technologically advanced animal. Along with the brain's internal complexity, the brain to body mass ratio is generally assumed to be a good indicator of relative intelligence. Humans have the second highest ratio, with the tree shrew having the highest [http://www.hindustantimes.com/news/181_935198,00300006.htm], and the bottlenose dolphin very similar to humans. The human ability to abstract may be unparalleled in the animal kingdom. Human beings are one of five species to pass the mirror test — which tests whether an animal recognises its reflection as an image of itself — along with chimpanzees or bonobos, orangutans, and dolphins. Human beings under the age of four usually fail the test.

Culture

dolphin]] Culture is defined here as a set of distinctive material, intellectual, emotional, and spiritual features of a social group, including art, literature, lifestyles, value systems, traditions, rituals, and beliefs. Culture consists of at least three elements: values, social norms, and artifacts. A culture's values define what it holds to be important. Norms are expectations of how people ought to behave. Artifacts — things, or material culture — derive from the culture's values and norms together with its understanding of the way the world functions.

Origins

Essentially every culture has its characteristic origin beliefs. Creationism or creation theology is the belief that humans, the Earth, the universe and the multiverse were created by a supreme being or deity. The event itself may be seen either as an act of creation (ex nihilo) or the emergence of order from preexisting chaos (demiurge). Many who hold "creation" beliefs consider such belief to be a part of religious faith, and hence compatible with, or otherwise unaffected by scientific views while others maintain the scientific data is compatible with creationism. Proponents of evolutionary creationism may claim that understood scientific mechanisms are simply aspects of supreme creation. Otherwise, science-oriented believers may consider the scriptural account of creation as simply a metaphor.

Language

metaphor, Chinese, Korean, Hebrew and Greek]] Values, norms and technology are dependent on the capacity for humans to share ideas. The faculty of speech may be a defining feature of humanity, probably predating phylogenetic separation of the modern population. (See Proto-World language, Origins of language.) Language is central to the communication between humans. Some scientists argue that non-human animals are able to use some form of language too, and that non-human primates are able to learn human sign language [http://www.mnsu.edu/emuseum/cultural/language/chimpanzee.html] [http://www.msubillings.edu/asc/PDF-WritingLab/3-Minute%20Spr05/APA%20sample%20paper.pdf] (pdf). Language is central to the sense of identity that unites cultures and ethnicities. The invention of writing systems some 5000 years ago, allowing the preservation of speech, was a major step in cultural evolution. Language, especially written language, is sometimes thought to have supernatural status or powers. (See Magic, Mantra, Vac.) The science of linguistics describes the structure of language and the relationship between languages. There are estimated to be some 6,000 different languages, including sign languages, used today.

Music

Music is a natural intuitive phenomenon operating in the three worlds of time, pitch, and energy, and under the three distinct and interrelated organisation structures of rhythm, harmony, and melody. Composing, improvising and performing music are all art forms. Listening to music is perhaps the most common form of entertainment, while learning and understanding it are popular disciplines. There are a wide variety of music genres and ethnic musics.

Emotion and sexuality

Human emotion has a significant influence on, or can even be said to control, human behaviour. Emotional experiences perceived as pleasant, like love, admiration, or joy, contrast with those perceived as unpleasant, like hate, envy, or sorrow. There is often a distinction seen between refined emotions, which are socially learned, and survival oriented emotions, which are thought to be innate. Human exploration of emotions as separate from other neurological phenomena is worth note, particularly in those cultures were emotion is considered separate from physiological state. In some cultural medical theories, to provide an example, emotion is considered so synonymous with certain forms of physical health that no difference is thought to exist. The Stoics believed excessive emotion was harmful, while some Sufi teachers (in particular, the poet and astronomer Omar Khayyám) felt certain extreme emotions could yield a conceptual perfection, what is often translated as ecstasy. ecstasy"]] In modern scientific thought, certain refined emotions are considered to be a complex neural trait of many domesticated and a few non-domesticated mammals, developed commonly in reaction to superior survival mechanisms and intelligent interaction with each other and the environment; as such, refined emotion is not in all cases as discrete and separate from natural neural function as was once assumed. Still, when humans function in civilised tandem, it has been noted that uninhibited acting on extreme emotion can lead to social disorder and crime. Human sexuality, besides ensuring reproduction, has important social functions, creating physical intimacy, bonds and hierarchies among individuals, and that may be directed to spiritual transcendence, and/or to the enjoyment of activity involving sexual gratification. Sexual desire, libido, is experienced as a bodily urge, often accompanied by strong emotions, both positive (such as love or ecstasy) and negative (such as jealousy). As with other human self-descriptions, humans propose it is high intelligence and complex societies of humans that have produced the most complex sexual behaviors of any animal. Human sexual choices are usually made in reference to cultural norms, which vary widely. Restrictions are largely determined by religious beliefs.

Body image

norms, Japan]]The physical appearance of the human body is central to culture and art. In every human culture, people adorn their bodies with tattoos, cosmetics, clothing, and jewellery. Hairstyles and hair colour also have important cultural implications. The perception of an individual as physically beautiful or ugly can have profound implications for their lives. This is particularly true of women, whose external appearance is highly valued in most, if not all, human societies. Anthropologists believe this to be an important factor in the development of personality and social relations in particular physical attractiveness. There is a relatively low sexual dimorphism between human males and females in comparison with other mammals.

Trade and economics

sexual dimorphism.]] Trade is the voluntary exchange of goods, services, or both, and a form of economics. A mechanism that allows trade is called a market. The original form of trade was barter, the direct exchange of goods and services. Modern traders instead generally negotiate through a medium of exchange, such as money. As a result, buying can be separated from selling, or earning. The invention of money (and later credit, paper money and non-physical money) greatly simplified and promoted trade. Trade exists for many reasons. Due to specialisation and division of labor, most people concentrate on a small aspect of manufacturing or service, trading their labour for products. Trade exists between regions because different regions have an absolute or comparative advantage in the production of some tradable commodity, or because different regions' size allows for the benefits of mass production. As such, trade between locations benefits both locations. Economics is a social science that studies the production, distribution, trade and consumption of goods and services. Economics, which focuses on measurable variables, is broadly divided into two main branches: microeconomics, which deals with individual agents, such as households and businesses, and macroeconomics, which considers the economy as a whole, in which case it considers aggregate supply and demand for money, capital and commodities. Aspects receiving particular attention in economics are resource allocation, production, distribution, trade, and competition. Economic logic is increasingly applied to any problem that involves choice under scarcity or determining economic value. Mainstream economics focuses on how prices reflect supply and demand, and uses equations to predict consequences of decisions.

Artifacts, technology, and science

supply and demand.]] Human cultures are both characterised and differentiated by the objects that they make and use. Archaeology attempts to tell the story of past or lost cultures in part by close examination of the artifacts they produced. Early humans left stone tools, pottery and jewellery that are particular to various regions and times. Improvements in technology are passed from one culture to another. For instance, the cultivation of crops arose in several different locations, but quickly spread to be an almost ubiquitous feature of human life. Similarly, advances in weapons, architecture and metallurgy are quickly disseminated. Such techniques can be passed on by oral tradition. The development of writing, itself a type of artifact, made it possible to pass information from generation to generation and from region to region with greater accuracy. Together, these developments made possible the commencement of civilisation and urbanisation, with their inherently complex social arrangements. Eventually this led to the institutionalisation of the development of new technology, and the associated understanding of the way the world functions. This science now forms a central part of human culture. In recent times, physics and astrophysics have come to play a central role in shaping what is now known as physical cosmology, that is, the understanding of the universe through scientific observation and experiment. This discipline, which focuses on the universe as it exists on the largest scales and at the earliest times, begins by arguing for the big bang, a sort of cosmic explosion from which the universe itself is said to have erupted ~13.7 ± 0.2 billion (10⁹) years ago. After its violent beginnings and until its very end, scientists then propose that the entire history of the universe has been an orderly progression governed by physical laws.

Mind

physical laws Consciousness is a state of mind, said to possess qualities such as, self-awareness, sentience, sapience, and the ability to perceive the relationship between oneself and one's environment. The way in which the world is experienced is the subject of much debate and research in philosophy of mind, psychology, brain biology, neurology, and cognitive science. Humans (and often others as well) are variously said to possess consciousness, self-awareness, and a mind, the fruition of being our senses and perceptions. Each of us has a subjective view of existence, the passage of time, and free will. There are many debates about the extent to which the mind constructs or experiences the outer world, and regarding the definitions and validity of many of the terms used above. Cognitive scientist Daniel Dennett, for example, argues that there is no such thing as a narrative centre called mind, but that instead there is simply a collection of sensory inputs and outputs: different kinds of software running in parallel (Dennett, 1991).

Psychology and human ethology

Psychology (Classical Greek: psyche = "soul" or "mind", logos = "study of") is the study of behaviour, mind and thought and the neurological basis for them. Psychoanalysis, the examination of the subconscious was, devised by Sigmund Freud and expanded and refined by the Swiss psychiatrist Carl Gustav Jung (initially one of Freud's followers and friends) and others. Carl Gustav Jung Freud divided the mind into the id (an individual's basic needs and instincts), the superego (personal and cultural values and norms), and the ego (the central, organising self, whose job it is to satisfy the id but not upset the superego). [http://allpsych.com/psychology101/ego.html] C. G. Jung founded the school of analytical psychology and introduced the notion of the collective unconscious, a term taken from philosophy and used by Jung to describe symbols or archetypes that he believed might be common to all cultures. There are also the Conscious, Subconscious, and Superconsciousness, a related but not identical set of categories. The behaviour and mental processes of animals (human and non-human) can be described through animal cognition, ethology, and comparative psychology as well. Human ecology is an academic discipline that investigates how humans and human societies interact with their environment, nature and the human social environment.

Philosophy

social environment in detail from Raphael's School of Athens]] Philosophy is a discipline or field of study involving the investigation, analysis, and development of ideas at a general, abstract, or fundamental level. It is the discipline searching for a general understanding of values and reality by chiefly speculative rather than observational means comprising as its core logic, ontology or metaphysics, epistemology, and axiology which includes the branches of ethics and aesthetics. The term covers a very wide range of approaches, and is also used to refer to a worldview, to a perspective on an issue, or to the positions argued for by a particular philosopher or school of philosophy. Metaphysics is a branch of philosophy concerned with the study of "first principles" and "being" (ontology). Problems that were not originally considered metaphysical have been added to metaphysics. Other problems that were considered metaphysical problems for centuries are now typically relegated to their own separate subheadings in philosophy, such as philosophy of religion, philosophy of mind, philosophy of perception, philosophy of language, and philosophy of science. In rare cases subjects of metaphysical research have been found to be entirely physical and natural. The mind is the term most commonly used to describe the higher functions of the human brain, particularly those of which humans are subjectively conscious, such as personality, thought, reason, memory, intelligence and emotion. Other species of animals share some of these mental capacities, and it is also used in relation to supernatural beings, as in the expression "the mind of God." The term is used here only in relation to humans. There are many Philosophies of mind, the most common relating to the nature of being, and ones way of being, or purpose. Adi Shankara in the East proposed Advaita Vedanta, a popular argument for monism (the metaphysical view that all is of one essential essence, substance or energy). Another type of monism is physicalism or Wikipedia:biology basic topics. --> Biology is the study, or 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 the environment. Biology encompasses a broad spectrum of academic fields that are often viewed as independent disciplines. However, together they address the phenomenon of life over a wide range of scales. At the atomic and molecular scale, life is studied in the disciplines of molecular biology, biochemistry, and molecular genetics. At the level of the cell, it is studied in cell biology, and at multicellular scales, it is examined in physiology, anatomy, and histology. Developmental biology studies life at the level of an individual organism's development or ontogeny. Moving up the scale towards more than one organism, genetics considers how heredity works between parent and offspring. Ethology considers group behavior of more than one individual. Population genetics looks at the level of an entire population, and systematics considers the multi-species scale of lineages. Interdependent populations and their habitats are examined in ecology and evolutionary biology. A speculative new field is astrobiology (or xenobiology), which examines the possibility of life beyond the Earth.

Biology studies the variety of life (clockwise from top-left) E. coli, tree fern, gazelle, Goliath beetle

Principles of biology

Unlike physics, biology does not usually describe systems in terms of objects which obey immutable physical laws described by mathematics. Nevertheless, the biological sciences are characterized and unified by several major underlying principles and concepts: universality, evolution, diversity, continuity, homeostasis, and interactions.

Universality: Biochemistry, cells, and the genetic code

mathematics]] Main articles: Life The most salient example of biological universality is that all living things share a common carbon-based biochemistry and in particular pass on their characteristics via genetic material, which is based on nucleic acids such as DNA and which uses a common genetic code with only minor variations. Another universal principle is that all organisms (that is, all forms of life on Earth except for viruses) are made of cells. Similarly, all organisms share common developmental processes. For example, in most metazoan organisms, the basic stages of early embryonic development share similar morphological characteristics and include similar genes.

Evolution: The central principle of biology

Main article: Evolution The central organizing concept in biology is that all life has a common origin and has changed and developed through the process of evolution (see Common descent). This has led to the striking similarity of units and processes discussed in the previous section. Charles Darwin established evolution as a viable theory by articulating its driving force, natural selection (Alfred Russell Wallace is recognized as the co-discoverer of this concept). Genetic drift was embraced as an additional mechanism of evolutionary development in the modern synthesis of the theory. The evolutionary history of a 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 (The major events in the evolution of life, as biologists currently understand them, are summarized on this evolutionary timeline).

Diversity: The variety of living organisms

evolutionary timeline, based on rRNA gene data, showing the separation of the three domains bacteria, archaea, and eukaryotes as described initially by Carl Woese. Trees constructed with other genes are generally similar, although they may place some early-branching groups very differently, presumably owing to rapid rRNA evolution. The exact relationships of the three domains are still being debated.]] Despite its underlying unity, life exhibits an astonishingly wide diversity in morphology, behavior, and life histories. In order to grapple with this diversity, biologists attempt to classify all living things. Scientific classification seeks to reflect the evolutionary trees (phylogenetic trees) of the organism being classified. Classification is the province of the disciplines of systematics and taxonomy. Taxonomy places organisms in groups called taxa, while systematics seeks to define their relationships with each other. This clasification technique has evolved to reflect advances in cladistics and genetics, shifting the focus from physical similarities and shared characteristics to phylogenetics. Traditionally, living things have been divided into five kingdoms: :Monera -- Protista -- Fungi -- Plantae -- Animalia However, many scientists now consider this five-kingdom system to be outdated. Modern alternative classification systems generally begin with the three-domain system: :Archaea (originally Archaebacteria) -- Bacteria (originally Eubacteria) -- Eukaryota These domains reflect whether the cells have nuclei or not, as well as differences in the cell exteriors. There is also a series of intracellular parasites that are progressively "less alive" in terms of metabolic activity: :Viruses -- Viroids -- Prions

Continuity: The common descent of life

Main article: Common descent Up into the 19th century, it was commonly believed that life forms could appear spontaneously under certain conditions (see abiogenesis). 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 is said to share a common descent if they share a common ancestor. All organisms on the Earth have been and 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).

Homeostasis: Adapting to change

Main article: Homeostasis Homeostasis is the ability of an open system to regulate its internal environment to maintain a stable condition by means of multiple dynamic equilibrium adjustments controlled by interrelated regulation mechanisms. All living organisms, whether unicellular or multicellular, exhibit homeostasis. Homeostasis manifests itself at the cellular level through the maintenance of a stable internal acidity (pH); at the organismic level, warm-blooded animals maintain a constant internal body temperature; and at the level of the ecosystem, as when atmospheric carbon dioxide levels rise and plants are theoretically able to grow healthier and remove more of the gas from the atmosphere. Tissues and organs can also maintain homeostasis.

Interactions: Groups and environments

organ of the genus Amphiprion that dwell among the tentacles of tropical sea anemones. The territorial fish protects the anemone from anemone-eating fish, and in turn the stinging tentacles of the anemone protects the anemone fish from its predators]] Every living thing interacts with other organisms and its environment. One reason that biological systems can be difficult to study is that so many different interactions with other organisms and the environment are possible, even on the smallest of scales. A microscopic bacterium responding to a local sugar gradient is responding to its environment as much as a lion is responding to its environment when it searches for food in the African savannah. For any given species, behaviors can be co-operative, aggressive, parasitic or symbiotic. Matters become more complex when two or more different species interact in an ecosystem. Studies of this type are the province of ecology.

Scope of biology

Main article: List of biology disciplines Biology has become such a vast research enterprise that it is not generally regarded as a single discipline, but as a number of clustered sub-disciplines. This article considers four broad groupings. The first group consists of those disciplines that study the basic structures of living systems: cells, genes etc.; the second group considers the operation of these structures at the level of tissues, organs, and bodies; the third group considers organisms and their histories; the final constellation of disciplines focuses on their interactions. It is important to note, however, that these boundaries, groupings, and descriptions are a simplified characterization of biological research. In reality, the boundaries between disciplines are fluid, and most disciplines frequently borrow techniques from each other. For example, evolutionary biology leans heavily on techniques from molecular biology to determine DNA sequences, which assist in understanding the genetic variation of a population; and physiology borrows extensively from cell biology in describing the function of organ systems.

Structure of life

DNA sequences and structures]] Main articles: Molecular biology, Cell biology, Genetics, Developmental biology Molecular biology is the study of biology at a molecular level. This field overlaps with other areas of biology, particularly with genetics and biochemistry. Molecular biology chiefly concerns itself with understanding the interactions between the various systems of a cell, including the interrelationship of DNA, RNA, and protein synthesis and learning how these interactions are regulated. Cell biology studies the physiological properties of cells, as well as their behaviors, interactions, and environment. This is done both on a microscopic and molecular level. Cell biology researches both single-celled organisms like bacteria and specialized cells in multicellular organisms like humans. Understanding cell composition and how they function is fundamental to all of the biological sciences. Appreciating the similarities and differences between cell types is particularly important in the fields of cell and molecular biology. These fundamental similarities and differences provide a unifying theme, allowing the principles learned from studying one cell type to be extrapolated and generalized to other cell types. Genetics is the science of genes, heredity, and the variation of organisms. In modern research, genetics provides important tools in the investigation of the function of a particular gene, or the analysis of genetic interactions. Within organisms, genetic information generally is carried in chromosomes, where it is represented in the chemical structure of particular DNA molecules. Genes encode the information necessary for synthesizing proteins, which in turn play a large role in influencing (though, in many instances, not completely determining) the final phenotype of the organism. Developmental biology studies the process by which organisms grow and develop. Originating in embryology, modern developmental biology studies the genetic control of cell growth, differentiation, and "morphogenesis," which is the process that gives rise to tissues, organs, and anatomy. Model organisms for developmental biology include the round worm Caenorhabditis elegans, the fruit fly Drosophila melanogaster, the zebrafish Brachydanio rerio, the mouse Mus musculus, and the weed Arabidopsis thaliana.

Physiology of organisms

Main articles: Physiology, Anatomy Physiology studies the mechanical, physical, and biochemical processes of living organisms by attempting to understand how all of the structures function as a whole. The theme of "structure to function" is central to biology. Physiological studies have traditionally been divided into plant physiology and animal physiology, but the principles of physiology are universal, no matter what particular organism is being studied. For example, what is learned about the physiology of yeast cells can also apply to human cells. The field of animal physiology extends the tools and methods of human physiology to non-human species. Plant physiology also borrows techniques from both fields. Anatomy is an important branch of physiology and considers how organ systems in animals, such as the nervous, immune, endocrine, respiratory, and circulatory systems, function and interact. The study of these systems is shared with medically oriented disciplines such as neurology and immunology.

Diversity and evolution of organisms

immunology of a population of organisms is sometimes depicted as if travelling on a fitness landscape. The arrows indicate the preferred flow of a population on the landscape, and the points A, B, and C are local optima. The red ball indicates a population that moves from a very low fitness value to the top of a peak]] Main articles: Evolutionary biology, Botany, Zoology Evolutionary biology is concerned with the origin and descent of species, as well as their change over time, and includes scientists from many taxonomically-oriented disciplines. For example, it generally involves scientists who have special training in particular organisms such as mammalogy, ornithology, or herpetology, but use those organisms as systems to answer general questions about evolution. Evolutionary biology also makes use of paleontologists, who use the fossil record to answer questions about the mode and tempo of evolution, as well as theoreticians in areas such as population genetics and evolutionary theory. In the 1990s, developmental biology re-entered evolutionary biology from its initial exclusion from the modern synthesis through the study of evolutionary developmental biology. Related fields which are often considered part of evolutionary biology are phylogenetics, systematics, and taxonomy. The two major traditional taxonomically-oriented disciplines are botany and zoology. Botany is the scientific study of plants. Botany covers a wide range of scientific disciplines that study the growth, reproduction, metabolism, development, diseases, and evolution of plant life. Zoology involves the study of animals, including the study of their physiology within the fields of anatomy and embryology. The common genetic and developmental mechanisms of animals and plants is studied in molecular biology, molecular genetics, and developmental biology. The ecology of animals is covered under behavioral ecology and other fields.

Classification of life

The dominant classification 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 these three areas, but it has yet to be formally adopted. The International Code of Virus Classification and Nomenclature (ICVCN) remains outside the BioCode.

Interactions of organisms

International Code of Virus Classification and Nomenclature]] Main articles: Ecology, Ethology, Behavior, Biogeography Ecology studies the distribution and abundance of living organisms, and the interactions between organisms and their environment. The environment of an organism includes both its habitat, which can be described as the sum of local abiotic factors such as climate and geology, as well as the other the organisms that share its habitat. Ecological systems are studied at several different levels, from individuals and populations to ecosystems and the biosphere. As can be surmised, ecology is a science that draws on several disciplines. Ethology studies animal behavior (particularly of social animals such as primates and canids), and is sometimes considered a branch of zoology. Ethologists have been particularly concerned with the evolution of behavior and the understanding of behavior in terms of the theory of natural selection. In one sense, the first modern ethologist was Charles Darwin, whose book The expression of the emotions in animals and men influenced many ethologists. Biogeography studies the spatial distribution of organisms on the Earth, focusing on topics like plate tectonics, climate change, dispersal and migration, and cladistics.

History of the word "biology"

Formed by combining the Greek βίος (bios), meaning 'life', and λόγος (logos), meaning 'study of', 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.

History

Main articles: History of biology, History of medicine, History of genetics Major discoveries in biology include:
- Cell theory
- Germ theory of disease
- Genetics
- Evolution
- DNA

External links

- [http://www.rom.on.ca/biodiversity/biocode/biocode1997.html BioCode]: A proposal for organism naming.
- [http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=Books NCBI Open-Access Books]
- PhyloCode, [http://www.ohiou.edu/phylocode/index.html]
- [http://tolweb.org/tree/phylogeny.html The Tree of Life]: A multi-authored, distributed Internet project containing information about phylogeny and biodiversity.
- [http://www.bioone.org/perlserv/?request=index-html BioOne] Bioscience research journals.
- [http://www.bionews.in/biologynews.htm Biology News] Biology News, Articles and Research discoversies.

Population density

Biological population densities

Human population density

See also

External links

Population

Population density

Population pyramid

Underpopulation

Overpopulation

Population control

Population decline

Population ageing

Population transfer

Population bomb

World population

Countries by population

See also

External links

Human

Terminology

Biology

Anatomy and physiology

Life cycle

Genetics

Race and ethnicity

Habitat

Population

Human evolution

Intelligence

Culture

Origins

Language

Music

Emotion and sexuality

Body image

Trade and economics

Artifacts, technology, and science

Mind

Psychology and human ethology

Philosophy

Principles of biology

Universality: Biochemistry, cells, and the genetic code

Evolution: The central principle of biology

Diversity: The variety of living organisms

Continuity: The common descent of life

Homeostasis: Adapting to change

Interactions: Groups and environments

Scope of biology

Structure of life

Physiology of organisms

Diversity and evolution of organisms

Classification of life

Interactions of organisms

History of the word "biology"

History

Related topics

External links

Further reading