The scientific study of human evolution encompasses the development of the genus Homo, but usually involves studying other hominids and hominines as well, such as Australopithecus. "Modern humans" are defined as the Homo sapiens species, of which the only extant subspecies is Homo sapiens sapiens; Homo sapiens idaltu (roughly translated as "elder wise human"), the other known subspecies, is extinct.  Anatomically modern humans appear in the fossil record in Africa about 130,000 years ago.
The closest living relatives of Homo sapiens are two distinct species of the genus Pan: the Bonobo (Pan paniscus) and the Common Chimpanzee (Pan troglodytes). These species share the same common ancestor. The main difference between them is the social organization: matriarchal for the Bonobo and patriarchal for the Common Chimpanzee. Full genome sequencing resulted in the conclusion that "after 6.5 million years of separate evolution, the differences between bonobo/chimpanzee and human are just 10 times greater than those between two unrelated people and 10 times less than those between rats and mice". In fact, 95 per cent of the DNA sequence is identical between the two Pan species and human.Frans de Waal, Bonobo ISBN 0-520-20535-9   | 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, a hominid skull discovered in Chad in 2001, classified as Sahelanthropus tchadensis, is approximately seven million years old, which may indicate an earlier divergence. 
The Recent African Origin (RAO), or "out-of-Africa", hypothesis proposes that modern humans evolved in Africa and later migrated outwards to replace hominids in other parts of the world. Evidence from Archaeogenetics accumulating since the 1990s has lent strong support to RAO and has marginalized the competing multiregional hypothesis, which proposed that modern humans evolved, at least in part, from independent hominid populations. 
Geneticists Lynn Jorde and Henry Harpending of the University of Utah proposed that the variation in human DNA is minute compared to that of other species. They also propose that during the Late Pleistocene, the human population was reduced to a small number of breeding pairs — no more than 10,000 and possibly as few as 1,000 — resulting in a very small residual gene pool. Various reasons for this hypothetical bottleneck have been postulated, one of those is the Toba catastrophe theory.
Human evolution is characterized by a number of important morphological, developmental, physiological and behavioral changes which have taken place since the split between the last common ancestor of Homo and Pan. The primary change, both in terms of chronology and in terms of it being the trait that defines the human subtribe the Hominina, was the evolution of a bipedal locomotor adaptation from an arboreal or semi-arboreal locomotor adaptation, with all its attendant adaptations, such as a valgus knee, low intermembral index (long legs relative to the arms) and reduced upper body strength. Following this was the evolution of a larger brain cavity and brain itself, which is typically 1,400 cm³ in modern humans; over twice that of a chimpanzee or gorilla. Other significant morphological changes included: the evolution of a power and precision grip; a reduced masticatory system; a reduction of the canine tooth; and the descent of the larynx and hyoid bone, making speech possible. With respect to development, the pattern of human postnatal brain growth differs from that of other apes (heterochrony), allowing for an extended period of social learning and language acquisition in juvenile humans. Physical anthropologists argue that a reorganization of the structure of the brain is more important than cranial expansion itself. One important physiological change in humans was the evolution of hidden estrus or concealed ovulation in females, which may have coincided with the evolution of important behavioral changes, such as pair bonding. Another significant behavioral change includes the development of material culture, or the (over time) increasingly wide variety of human-made objects which are used to manipulate humans' physical and social environments. How all these changes are related and what their role is in the evolution of complex social organization and culture are matters of ongoing debate.(How Humans Evolved, ISBN 0-393-97854-0]
Rise of civilization
The most widely accepted view among current anthropologists is that Homo sapiens originated in the African savanna around 200,000 BP (Before Present), descending from Homo erectus, had inhabited Eurasia and Oceania by 40,000 BP, and finally inhabited the Americas approximately 10,000 years ago. "Out of Africa again and again" They displaced Homo neanderthalensis and other species descended from Homo erectus (which had inhabited Eurasia as early as 2 million years ago) through more successful reproduction and competition for resources.
Up until only around 10,000 years ago, all humans lived as hunter-gatherers (with some communities persisting until this day). They generally lived in small, nomadic groups. The advent of agriculture prompted the Neolithic Revolution. Access to food surplus led to the formation of permanent human settlements, the domestication of animals, and the use of metal tools. Agriculture also encouraged trade and cooperation, leading to complex societies. Villages developed into thriving civilizations in regions such as the Middle East's Fertile Crescent.
Around 6,000 years ago, the first proto-states developed in Mesopotamia, Egypt and the Indus Valley. Military forces were formed for protection, and government bureaucracies for administration. States cooperated and competed for resources, in some cases waging wars. Around 2,000 – 3,000 years ago, some states, such as Persia, China, and Rome, developed through conquest into the first expansive empires. Influential religions, such as Judaism, originating in the Middle East, and Hinduism, a religious tradition that originated in South Asia, also rose to prominence at this time.
The late Middle Ages saw the rise of revolutionary ideas and technologies. In China, an advanced and urbanized economy promoted innovations such as printing and the compass, while the Islamic Golden Age saw major scientific advancements in Muslim empires. In Europe, the rediscovery of classical learning and inventions such as the printing press led to the Renaissance in the 14th century. Over the next 500 years, exploration and imperialistic conquest brought much of the Americas, Asia, and Africa under European control, leading to later struggles for independence. The Scientific Revolution in the 17th century and the Industrial Revolution in the 18th – 19th centuries promoted major innovations in transport, such as the railway and automobile; energy development, such as coal and electricity; and government, such as representative democracy and Communism.
As a result of such changes, modern humans live in a world that has become increasingly globalized and interconnected. Although this has encouraged the growth of science, art, and technology, it has also led to culture clashes, the development and use of weapons of mass destruction, and increased environmental destruction and pollution.
Habitat and population
Early human settlements were 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 hunting populations of prey. However, humans have a great capacity for altering their habitats by various methods, such as through irrigation, urban planning, construction, transport, and manufacturing goods. With the advent of large-scale trade and transport infrastructure, proximity to these resources has become unnecessary, and in many places these factors are no longer a driving force behind the growth and decline of a population. Nonetheless, the manner in which a habitat is altered is often a major determinant in population change.
Technology has allowed humans to colonize all of the continents and adapt to all climates. Within the last few decades, humans have explored Antarctica, the ocean depths, and space, although long-term habitation of these environments is not yet possible. With a population of over six billion, humans are among the most numerous of the large mammals. Most humans (61%) live in Asia. The vast majority of the remainder live in the Americas (14%), Africa (13%) and Europe (12%), with 0.5% in Oceania. (See list of countries by population and list of countries by population density.)
Human habitation within closed ecological systems in hostile environments, such as Antarctica and outer space, is expensive, typically limited in duration, and restricted to scientific, military, or industrial expeditions. Life in space has been very sporadic, with no more than thirteen humans in space at any given time. Between 1969 and 1972, two humans at a time spent brief intervals on the Moon. As of 2007, no other celestial body has been visited by human beings, although there has been a continuous human presence in outer space since the launch of the initial crew to inhabit the International Space Station on October 31, 2000; however, humans have made robots that have visited other celestial bodies.
From AD 1800 to 2000, the human population increased from one billion to six billion. In 2004, around 2.5 billion out of 6.3 billion people (39.7%) lived in urban areas, and this percentage is expected to rise throughout the 21st century. Problems for humans living in cities include various forms of pollution and crime, especially in inner city and suburban slums. Benefits of urban living include increased literacy, access to the global canon of human knowledge and decreased susceptibility to rural famines.
Humans have had a dramatic effect on the environment. It has been hypothesized that in the past, human predation has contributed to the extinction of a number of species; as humans are not generally preyed on themselves, humans have been described as the ultimate superpredators.'Scientific American Evolution and General Intelligence: Three hypotheses on the evolution of general intelligence. Currently, through land development and pollution, humans are thought to be the main contributor to global climate change.  This is believed to be a major contributor to the ongoing Holocene extinction event, a mass extinction which, if it continues at its current rate, is predicted to wipe out half of all species over the next century.
Physiology and genetics
Human body types vary substantially. Although body size is largely determined by genes, it is also significantly influenced by environmental factors such as diet and exercise. The average height of an adult human is about 5 to 6 feet (1.5 to 1.8 m) tall, although this varies significantly from place to place. Britannica Concise Encyclopedia. Encyclopædia Britannica, Inc., 2006.  Humans are capable of fully bipedal locomotion, thus leaving their arms available for manipulating objects using their hands, aided especially by opposable thumbs.
Although humans appear relatively hairless compared to other primates, with notable hair growth occurring chiefly on the top of the head, underarms and pubic area, the average human has more hair follicles on his or her body than the average chimpanzee. The main distinction is that human hairs are shorter, finer, and less heavily pigmented than the average chimpanzee's, thus making them harder to see.Cite error: Closing
</ref> missing for
<ref> tag While one in five Europeans is 60 years of age or older, only one in twenty Africans is 60 years of age or older. [The World Factbook]
The number of centenarians (humans of age 100 years or older) in the world was estimated by the United Nations at 210,000 in 2002. At least one person, Jeanne Calment, is known to have reached the age of 122 years; higher ages have been claimed but they are not well substantiated. Worldwide, there are 81 men aged 60 or older for every 100 women of that age group, 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 causes unease or fear for most humans. Burial ceremonies are characteristic of human societies, often accompanied by beliefs in an afterlife or immortality.
Early Homo sapiens employed a hunter-gatherer method as their primary means of food collection, involving combining stationary plant and fungal food sources (such as fruits, grains, tubers, and mushrooms) with wild game which must be hunted and killed in order to be consumed. It is believed that humans have used fire to prepare and cook food prior to eating since the time of their divergence from Homo erectus.
Humans are omnivorous, capable of consuming both plant and animal products. The view of humans as omnivores is supported by the evidence that both a pure animal and a pure vegetable diet can lead to deficiency diseases in humans. A pure animal diet can, for instance, lead to scurvy, while a pure plant diet can lead to deficiency of a number of nutrients, including Vitamin B12. Supplementation, particularly for vitamin B12, is highly recommended for people living on a pure plant diet. However, according to American Dietetic Association and the Dietitians of Canada, properly planned vegetarian and vegan diets are nutritionally adequate and healthy.
The human diet is prominently reflected in human culture, and has led to the development of food science. In general, humans can survive for two to eight weeks without food, depending on stored body fat. Survival without water is usually limited to three or four days. Lack of food remains a serious problem, with about 300,000 people starving to death every year. Childhood malnutrition is also common and contributes to the global burden of disease. However global food distribution is not even, and obesity among some human populations has increased to almost epidemic proportions, leading to health complications and increased mortality in some developed, and a few developing countries. The United States Centers for Disease Control (CDC) state that 32% of American adults over the age of 20 are obese, while 66.5% are obese or overweight. Obesity is caused by consuming more calories than are expended, with many attributing excessive weight gain to a combination of overeating and insufficient exercise.
At least ten thousand years ago, humans developed agriculture, which has substantially altered the kind of food people eat. This has led to increased populations, the development of cities, and because of increased population density, the wider spread of infectious diseases. The types of food consumed, and the way in which they are prepared, has varied widely by time, location, and culture.
The human brain is the center of the central nervous system in humans, as well as the primary control center for the peripheral nervous system. The brain controls "lower", or involuntary, autonomic activities such as the respiration, and digestion. The brain also controls "higher" order, conscious activities, such as thought, reasoning, and abstraction. These cognitive processes constitute the mind, and, along with their behavioral consequences, are studied in the field of psychology.
The human brain is generally regarded as more capable of these higher order activities, and more "intelligent" in general, than that of any other species. While other animals are capable of creating structures and using simple tools — mostly as a result of instinct and learning through mimicry — human technology is vastly more complex, constantly evolving and improving with time. Even the most ancient human tools and structures are far more advanced than any structure or tool created by any other animal.
Consciousness and thought
The human ability to think abstractly may be unparalleled in the animal kingdom. Humans are one of only six species to pass the mirror test — which tests whether an animal recognizes its reflection as an image of itself — along with chimpanzees, orangutans, dolphins, and possibly pigeonsCite error: Closing
</ref> missing for
<ref> tag Phenomenal consciousness is the state of being conscious, such as when they say "I am conscious." Access consciousness is being conscious of something in relation to abstract concepts, such as when one says "I am conscious of these words." Various forms of access consciousness include awareness, self-awareness, conscience, stream of consciousness, Husserl's phenomenology, and intentionality. The concept of phenomenal consciousness, in modern history, according to some, is closely related to the concept of qualia.
Social psychology links sociology with psychology in their shared study of the nature and causes of human social interaction, with an emphasis on how people think towards each other and how they relate to each other. The behavior and mental processes, both human and non-human, can be described through animal cognition, ethology, evolutionary psychology, and comparative psychology as well. Human ecology is an academic discipline that investigates how humans and human societies interact with both their natural environment and the human social environment.
Motivation and emotion
Motivation is the driving force of desire behind all deliberate actions of human beings. Motivation is based on emotion — specifically, on the search for satisfaction (positive emotional experiences), and the avoidance of conflict. Positive and negative is defined by the individual brain state, which may be influenced by social norms: a person may be driven to self-injury or violence because their brain is conditioned to create a positive response to these actions. Motivation is important because it is involved in the performance of all learned responses.
Within psychology, conflict avoidance and the libido are seen to be primary motivators. Within economics motivation is often seen to be based on financial incentives, moral incentives, or coercive incentives. Religions generally posit divine or demonic influences.
Happiness, or being happy, is a human emotional condition. The definition of happiness is a common philosophical topic. Some people might define it as the best condition which a human can have — a condition of mental and physical health. Others may define it as freedom from want and distress; consciousness of the good order of things; assurance of one's place in the universe or society, inner peace, and so forth.
Human emotion has a significant influence on, or can even be said to control, human behavior, though historically many cultures and philosophers have for various reasons discouraged allowing this influence to go unchecked.
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 worthy of note, particularly in those cultures where 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.
In modern scientific thought, certain refined emotions are considered to be a complex neural trait of many domesticated and a few non-domesticated mammals. These were commonly developed 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 civilized tandem, it has been noted that uninhibited acting on extreme emotion can lead to social disorder and crime.
Love and sexuality
Human sexuality, besides ensuring biological reproduction, has important social functions: it creates physical intimacy, bonds, and hierarchies among individuals; may be directed to spiritual transcendence (according to some traditions); and in a hedonistic sense to the enjoyment of activity involving sexual gratification. Sexual desire, or libido, is experienced as a bodily urge, often accompanied by strong emotions such as love, ecstasy and jealousy.
As with other human self-descriptions, humans propose that it is high intelligence and complex societies of humans that have produced the most complex sexual behaviors of any animal, including a great many behaviors that are not directly connected with reproduction.
Human sexual choices are usually made in reference to cultural norms, which vary widely. Restrictions are sometimes determined by religious beliefs or social customs.
Many sexologists believe that the majority of Homo sapiens have the inherent capacity to be attracted to both males and females (a kind of universal potential bisexuality). In a variation of this, pioneering researcher Sigmund Freud believed that humans are born polymorphously perverse, which means that any number of objects could be a source of pleasure. According to Freud, humans then pass through five stages of psychosexual development (and can fixate on any stage because of various traumas during the process). For Alfred Kinsey, another influential sex researcher, people can fall anywhere along a continuous scale of sexual orientation (with only small minorities fully heterosexual or homosexual). Recent studies of neurology and genetics suggest people may be born with one sexual orientation or another, so there is not currently a clear consensus among sex researchers.Cite error: Closing
</ref> missing for
Politics is the process by which decisions are made within groups. Although the term is generally applied to behavior within governments, politics is also observed in all human group interactions, including corporate, academic, and religious institutions. Many different political systems exist, as do many different ways of understanding them, and many definitions overlap. The most common form of government worldwide is a republic, however other examples include monarchy, social democracy, military dictatorship and theocracy.
All of these issues have a direct relationship with economics.
War is a state of widespread conflict between states, organizations, or relatively large groups of people, which is characterized by the use of lethal violence between combatants or upon civilians. It is estimated that during the 20th century between 167 and 188 million humans died as a result of war.
A common perception of war is a series of military campaigns between at least two opposing sides involving a dispute over sovereignty, territory, resources, religion or other issues. A war said to liberate an occupied country is sometimes characterized as a "war of liberation", while a war between internal elements of a state is a civil war. Full scale pitched-battle wars between adversaries of comparable strength appear to have nearly disappeared from human activity, with the last major one in the Congo region winding down in the late 1990's. Nearly all war now is asymmetric warfare, in which campaigns of sabotage, guerrilla warfare and sometimes acts of terrorism disrupt control and supply of better-equipped occupying forces, resulting in long low-intensity wars of attrition.
There have been a wide variety of rapidly advancing tactics throughout the history of war, ranging from conventional war to asymmetric warfare to total war and unconventional warfare. Techniques include hand to hand combat, the use of ranged weapons, and ethnic cleansing. Military intelligence has often played a key role in determining victory and defeat. Propaganda, which often includes factual information, slanted opinion and disinformation, plays a key role in maintaining unity within a warring group, and/or sowing discord among opponents. In modern warfare, soldiers and armoured fighting vehicles are used to control the land, warships the sea, and air power the sky. Outer space has recently become a factor in warfare as well, although no actual warfare is currently carried out in space.
War is a strong catalyst in technology. Throughout history there has been a constant struggle between defense and offense, for example between armour and the weapons designed to breach it. Modern examples include the bunker buster bomb, and the bunkers which they are designed to destroy. Important inventions such as medicine, navigation, metallurgy, mass production, nuclear power, rocketry and computers have been completely or partially driven by war.
Trade and economics
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. Because of specialization 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 tradeable commodity, or because different regions' size allows for the benefits of mass production.
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.
- Archaeology Info
- Chororapithecus abyssinicus Possible human-orangutan split 20 million years ago. (Aug 26 2007)
- American Association for the Advancement of Science. Foreword. AAAS Atlas of Population & Environment. Wilson, E.O. (2002). in The Future of Life.
- U.N. Statistics on Population Ageing, United Nations press release, February 28, 2002, retrieved April 2, 2005
- Death and DALY estimates for 2002 by cause for WHO Member States World Health Organisation. Accessed 29 Oct 2006
- Earliest agriculture in the Americas Earliest cultivation of barley Earliest cultivation of figs - URLs retrieved February 19, 2007
- 3-D Brain Anatomy, The Secret Life of the Brain, Public Broadcasting Service, retrieved April 3 2005.
- Sagan, Carl (1978). The Dragons of Eden. A Ballantine Book. ISBN 0-345-34629-7
- Jonathan Benthall Animal liberation and rights Anthropology Today Volume 23 Issue 2 Page 1 - April 2007
- Buss, David M. (2004) "The Evolution of Desire: Strategies of Human Mating". Revised Edition. New York: Basic Books"
- Ferguson, Niall. "The Next War of the World." Foreign Affairs, Sep/Oct 2006