Overview of Humans

From Wikipedia, the free encyclopedia

Humans, a Middle English term are also known as Homo sapiens are the only living species in the Homo genus of bipedal primates in the great ape family. Anatomically modern humans originated in Africa about 200,000 years ago, reaching full behavioral modernity around 50,000 years ago.

Humans have a highly developed brain, capable of abstract reasoning, language, introspection, and problem solving. This mental capability, combined with an erect body carriage that frees the hands for manipulating objects, has allowed humans to make far greater use of tools than any other living species on Earth. Other higher-level thought processes of humans, such as self-awareness, rationality and sapience, are considered to be defining features of what constitutes a “person”.

Like most higher primates, humans are social animals. However, humans are uniquely adept at utilizing systems of communication for self-expression, the exchange of ideas, and organization. Humans create complex social structures composed of many cooperating and competing groups, from families to nations. Social interactions between humans have established an extremely wide variety of values, social norms, and rituals, which together form the basis of human society. With individuals widespread in every continent except Antarctica, humans are a cosmopolitan species. As of August 2010, the population of humans was estimated to be about 6.8 billion.

Humans are unique in their desire to understand and influence their environment through bio-engineering; seeking to explain and manipulate phenomena through science, philosophy, mythology and religion. This natural curiosity has led to the development of advanced tools and skills, which are passed down culturally; humans are the only species known to build fires, cook their food, clothe themselves, and use numerous other technologies. The study of humans is the scientific discipline of anthropology.


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 1.5 to 1.8 m (5 to 6 feet) tall, although this varies significantly from place to place. The average mass of an adult human is 54–64 kg (120–140 lbs) for females and 76–83 kg (168–183 lbs) for males. Unlike most other primates, humans are capable of fully bipedal locomotion, thus leaving their arms available for manipulating objects using their hands, aided especially by opposable thumbs that make grasping and fine detail work possible.

The hue of human skin and hair is determined by the presence of pigments called melanin. Human skin hues can range from very dark brown to very pale pink. Human hair ranges from white to brown to red to most commonly black. Most researchers believe that skin darkening was an adaptation that evolved as a protection against ultraviolet solar radiation. Humans tend to be physically weaker than other similarly sized primates, with young, conditioned male humans having been shown to be unable to match the strength of female orangutans which are at least three times stronger. The construction of modern human shoulders enables throwing weapons, which also were much more difficult or even impossible for Neanderthal competitors to use effectively.

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. By present estimates, humans have approximately 20,000–25,000 genes. 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 carries many genes not on the Y chromosome, which means that recessive diseases associated with X-linked genes, such as hemophilia, affect men more often than women.

Life cycle 
The human life cycle is similar to that of other placental mammals. The zygote divides inside the female’s uterus to become an embryo, which over a period of thirty-eight weeks (9 months) of gestation becomes a fetus. After this span of time, the fully grown fetus is birthed from the woman’s body and breathes independently as an infant for the first time.
In developed countries, infants are typically 3–4 kg (6–9 pounds) in weight and 50–60 cm (20–24 inches) in height at birth. However, low birth weight is common in developing countries, and contributes to the high levels of infant mortality in these regions. Helpless at birth, humans continue to grow for some years, typically reaching sexual maturity at 12 to 15 years of age. Females continue to develop physically until around the age of 18, whereas male development continues until around age 21. The human life span can be split into a number of stages: infancy, childhood, adolescence, young adulthood, adulthood and old age. The lengths of these stages, however, have varied across cultures and time periods. Compared to other primates, humans experience an unusually rapid growth spurt during adolescence, where the body grows 25% in size. Chimpanzees, for example, grow only 14%, with no pronounced spurt. The presence of the growth spurt is probably necessary to keep children physically small until they are psychologically mature. Humans are one of the few species in which females undergo menopause.
There are significant differences in life expectancy around the world. The developed world is generally aging, with the median age around 40 years. In the developing world the median age is between 15 and 20 years. Life expectancy at birth in Hong Kong is 84.8 years for a female and 78.9 for a male.  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 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 is known to have reached the age of 122 years. 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.

Humans are omnivorous, capable of consuming plant, animal, and inorganic material. Human groups have adopted a range of diets, from purely vegetarian to primarily carnivorous. In some cases, dietary restrictions in humans can lead to deficiency diseases; however, stable human groups have adapted too many dietary patterns through both genetic specialization and cultural conventions to use nutritionally balanced food sources.
Until the development of agriculture approximately 10,000 years ago, Homo sapiensemployed a hunter-gatherer method as their sole means of food collection. This involved combining stationary food sources (such as fruits, grains, tubers, and mushrooms, insect larvae and aquatic mollusks) with wild game, which must be hunted and killed in order to be consumed.It has been proposed that members of H. sapiens have used fire to prepare and cook food since the time of their divergence from Homo rhodesiensis. Around ten thousand years ago, humans developed agriculture, which substantially altered their diet. This change in diet may also have altered human biology; with the spread of dairy farming providing a new and rich source of food, leading to the evolution of the ability to digest lactose in some adults. Agriculture 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.
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 36 million humans 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 rapidly, leading to health complications and increased mortality in some developed, and a few developing countries. Worldwide over one billion people are obese, while in the United States 35% of people are obese, leading to this being described as an “obesity epidemic”. Obesity is caused by consuming more calories than are expended, so excessive weight gain is usually caused by a combination of an energy-dense high fat diet and insufficient exercise.

Humans are generally diurnal. The average sleep requirement is between seven and nine continuous hours a day for an adult and nine to ten hours for a child; elderly people usually sleep for six to seven hours.


The human brain, the focal point of the central nervous system in humans, controls the peripheral nervous system. In addition to controlling “lower”, involuntary, or primarily autonomic activities such as respiration and digestion, it is also the locus of “higher” order functioning 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.
Generally regarded as more capable of these higher order activities, the human brain is believed to be more “intelligent” in general than that of any other known species. Some are capable of creating structures and using simple tools—mostly through instinct and mimicry—human technology is vastly more complex, and is constantly evolving and improving through time.

Consciousness and thought
Humans are one of only nine species to pass the mirror test—which tests whether an animal recognizes its reflection as an image of itself—along with all the great apes (gorillas, chimpanzees, orangutans), Bottlenose dolphins, Asian elephants, European Magpies and Orcas. Most human children will pass the mirror test at 18 months old. However, the usefulness of this test as a true test of consciousness has been disputed, and this may be a matter of degree rather than a sharp divide. Monkeys have been trained to apply abstract rules in tasks.
The human brain perceives the external world through the senses, and each individual human is influenced greatly by his or her experiences, leading to subjective views of existence and the passage of time. Humans are variously said to possess consciousness, self-awareness, and a mind, which correspond roughly to the mental processes of thought. These are said to possess qualities such as self-awareness, sentience, sapience, and the ability to perceive the relationship between oneself and one’s environment. The extent to which the mind constructs or experiences the outer world is a matter of debate, as are the definitions and validity of many of the terms used above.
The nature of thought is central to psychology and related fields. Cognitive psychology studies cognition, the mental processes’ underlying behavior. It uses information processing as a framework for understanding the mind, perception, learning, problem solving, memory, attention, language and emotion.  Developmental psychology seeks to understand how people come to perceive, understand, and act within the world and how these processes change as they age. This may focus on intellectual, cognitive, neural, social, or moral development.
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, and intentionality. The concept of phenomenal consciousness, in modern history, according to some, is closely related to the concept of Jana Yoga and Buddhist Awareness.

Motivation and emotion
Motivation is the driving force of desire behind all deliberate actions of humans. 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 incentives; these may be financial, moral, or coercive. Religions generally posit divine or demonic influences.
Happiness, or the state of being happy, is a human emotional condition. Some people might define it as the best condition that a human can have—a condition of mental and physical health. Others 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.
Emotion has a significant influence on, or can even be said to control, human behavior.  Emotional experiences perceived as pleasant, such as love, admiration, or joy, contrast with those perceived as unpleasant, like hate, envy, or sorrow. There is often a distinction made between refined emotions that are socially learned and survival oriented emotions, which are thought to be innate. The Stoics believed excessive emotion was harmful, while some Sufi teachers felt certain extreme emotions could yield a conceptual perfection, what is often translated as ecstasy.

Sexuality and love
Human sexuality, besides ensuring biological reproduction, has important social functions: it creates physical intimacy, bonds, and hierarchies among individuals; 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.  Restrictions are often determined by religious beliefs or social customs.

Gender roles
The sexual division of humans into male and female has been marked culturally by a corresponding division of roles, norms, practices, dress, behavior, rights, duties, privileges, status, and power. Cultural differences by gender have often been believed to have arisen naturally out of a division of reproductive labor; the biological fact that women give birth led to their further cultural responsibility for nurturing and caring for children and households.

Race and ethnicity
Humans often categorize themselves in terms of race or ethnicity, sometimes on the basis of differences in appearance. Human racial categories have been based on both ancestry and visible traits, especially facial features, skin color and hair texture. Most current genetic and archaeological evidence supports a recent single origin of modern humans in East Africa.

The capacity humans have to transfer concepts, ideas and notions through speech and writing is unrivaled in known species. Unlike the call systems of other primates that are closed, human language is far more open, and gains variety in different situations.  The faculty of speech is a defining feature of humanity. Language is central to the communication between humans, as well as being central to the sense of identity that unites nations, cultures and ethnic groups. The invention of writing systems at least 5,000 years ago allowed the preservation of language on material objects, and was a major step in cultural evolution.

Spirituality and religion

Religion is generally defined as a belief system concerning the supernatural, sacred or divine, and practices, values, institutions and rituals associated with such belief. Some religions also have a moral code. Religion has taken on many forms that vary by culture and individual perspective. Some of the chief questions and issues religions are concerned with include life after death (commonly involving belief in an afterlife), the origin of life, the nature of the universe (religious cosmology) and its ultimate fate , and what is moral or immoral. A common source in religions for answers to these questions are beliefs in transcendent divine beings such as deities or a singular God, although not all religions are theistic—many are monotheistic or ambiguous on the topic, particularly among the Eastern religions.
Spirituality, belief or involvement in matters of the soul or spirit, is one of the many different approaches humans take in trying to answer fundamental questions about humankind’s place in the universe, the meaning of life, and the ideal way to live one’s life.  Spirituality is unique in that it focuses on mystical or supernatural concepts such as karma and God.
Although the exact level of religiosity can be hard to measure, a majority of humans professes some variety of religious or spiritual belief, although some are irreligious: that is lacking or rejecting belief in the supernatural or spiritual. Other humans have no religious beliefs and are atheists, scientific skeptics, agnostics or simply non-religious. Humanism is a philosophy which seeks to include all of humanity and all issues common to humans; it is usually non-religious. Additionally, although most religions and spiritual beliefs are clearly distinct from science on both a philosophical and methodological level, the two are not generally considered mutually exclusive; a majority of humans holds a mix of both scientific and religious views. The distinction between philosophy and religion, on the other hand, is at times less clear, and the two are linked in such fields as the philosophy of religion and theology.

Philosophy and self-reflection
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 reality, reasoning and values. Major fields of philosophy include logic, metaphysics, epistemology, philosophy of mind, and axiology (which includes ethics and aesthetics). Philosophy covers a very wide range of approaches, and is 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.
Human self-reflection is the capacity of humans to exercise introspection and the willingness to learn more about their fundamental nature, purpose and essence. The earliest historical records demonstrate the great interest which humanity has had in itself. Human self-reflection invariably leads to inquiry into the human condition and the essence of humankind as a whole.  However, it could be argued that a culture of self obsession leads to more self-reflection, since, in the quest for the ideal life, individuals will constantly analyze their characters, faults and ambitions. This can be shown in the trend to seek psychotherapy as the panacea to one’s emotional woes.
Spiritual movements that encourage the reflective arts of prayer and meditation as a practice are on the rise, both as branches of existing religions and as part of more eclectic movements like the New Age.

Art, music, and literature
Artistic works have existed for almost as long as humankind, from early pre-historic art to contemporary art. Art is one of the most unusual aspects of human behavior and a key distinguishing feature of humans from other species. Art is commonly understood to be the process or result of making material works that, from concept to creation, adhere to the “creative impulse” of human beings. Art is distinguished from other works by being in large part unprompted by necessity, by biological drive, or by any undisciplined pursuit of recreation.

Music is a natural intuitive phenomenon based on the three distinct and interrelated organization structures of rhythm, harmony, and melody. Listening to music is perhaps the most common and universal form of entertainment for humans, while learning and understanding it are popular disciplines.

Comparison to Other Species

Various attempts have been made to identify a single behavioral characteristic that distinguishes humans from all other animals. Some anthropologists think that readily observable characteristics (tool-making and language) are based on less easily observable mental processes that might be unique among humans: the ability to think symbolically, in the abstract or logically,

Traits That Define Human Nature
There has been one question pondered equally between scientists, philosophers and the common man throughout history.  What defines humans as such? What does it mean to be human?  The five most accepted traits that define human nature: bipedalism, material culture, hunting, domestication and symbolic culture

The term bipedalism means to walk upright and while this is not truly unique to man; it remains a very rare trait. Primates are the obvious closest living ancestor, some of which are bipedal.

The reason bipedalism is so key to human beings is because ancient ancestors of the species were not bipedal. This is because they lived primarily in trees. However, for whatever reason, being environmental or morphological, the genus Homo developed as a bipedal creature.

Dependence on Material Culture
Material culture is a broad term and it can refer to the obvious, present day items such as clothing or even an MP3 player. However, in terms of archaeology, the first dependence on materials would be stone tools.
Use of stone tools began over 2.5 million years ago and is considered to be one of the first human technologies. Tool use may have possibly begun with Australopithecines; however it is generally associated with a species called Homohabilis. H. habilis is one of the first documented species in the Homo genus of which humans are the last.

Stone tools started out extremely basic. Without a trained eye, many would think they were simply stones chipped by the river current. These stones were however, of great use to the H. habilis. They used them for digging holes, cutting meat and finding tubers for food. Once these tools were invented, they were heavily relied upon. Technologies and dependence upon them is without question a quality unique to Homo sapiens.

Hunting and Domestication
Along with the advent of tools, came hunting. Now that Hominids had tools, they used them to hunt animals, rather than simply scavenging. There is evidence over a million years old of cut marks on animal bones that archaeologists believe were created by throwing a spear. Human ancestors were now organizing hunts. This involves a great deal of communication and understanding. By 1 million years ago, Hominids were group hunting, not unlike the pack hunting done by wolves.

Symbolic Behavior and Culture
Without doubt, the most striking and perplexing quality of the human species is the capability of symbolic behavior and creation of culture. Anthropologist Robin Dunbar states, “The real differences [between apes and man] lie in our capacity to live in an imagined world.” He explains that all other species are so focused on everyday life that they do not stop to be curious about anything. Stephen Oppenheimer adds that humans seem to be the only species that could or wanted to ask a question.

The introduction of material culture began over 2 million years ago in cave walls, with jewelry and burial items. Why symbolism suddenly appears in the ancestral timeline is unknown but it is clear. One of the most famous pieces of evidence is Chauvet Cave in France. It is full of wall drawings of animals and even a few human representations that date back to 32 000 years ago.

Other Human Unique Characteristics
Mythology and science grew out of that same human characteristic: curiosity about the world and the wonder of what humans could achieve. It is perhaps this quality that led humans to do other unique behaviors such as creating food recipes, fashion and even borders around countries. Fascinatingly enough, Humans are only species who have both the intelligence and ambition to create boats, airplanes and spaceships.

Philosophical and Religious Conceptions

Non-Dualist Vs  Dualist 
When you realize that the nature of your mind and the Universe are non-dual, you are enlightened. Dualism asserts that mind and matter are fundamentally distinct kinds of substances.  The mind sees itself separate from its own physical body and to all other entities outside of itself.  There is a separation of us and them.

Plato stated the meaning of life is in attaining the highest form of knowledge, which is the Idea of the Good, from which all good and just things derive utility and value.

Aristotle argued that ethical knowledge is general knowledge. A person had to study and practice in order to become ‘good’, thus if the person were to become virtuous, he had to be virtuous, via virtuous activities. Aristotle’s solution is the Highest Good.  It is its own goal.

The Cynic philosophers said that the purpose of life is living a life of Virtue that agrees with Nature. Happiness depends upon being self-sufficient and master of one’s mental attitude; suffering is consequence of false judgments of value, which cause negative emotions and a concomitant vicious character.

The Cynical life rejects conventional desires for wealth, power, health, and fame, by being free of the possessions acquired in pursuing the conventional.  As reasoning creatures, people could achieve happiness via rigorous training, by living in a way natural to human beings. The world equally belongs to everyone, so suffering is caused by false judgments of what is valuable and what is worthless per the customs and conventions of society.

Stoicism’s prime directives are virtue, reason, and natural law, abided to develop personal self-control and mental fortitude as means of overcoming destructive emotions. The Stoic does not seek to extinguish emotions, only to avoid emotional troubles, by developing clear judgment and inner calm through diligently practiced logic, reflection, and concentration.  One’s personal relations are to be free from anger, envy, and jealousy.

Pragmatism posits that anything useful and practical is not always true; arguing that what most contributes to the most human good in the long course is true.

General Religious Aphorisms

  1. Seek knowledge and oneness with God
  2. Awareness of Life leads to respect of all sentient Beings
  3. The creation of positive action leads to happiness
  4. Life contains a series of lessons from which we must learn a higher moral standard of living.
  5. Life is inherent with suffering or frustration.
  6. This doesn’t mean there is no pleasure in life, but pleasure doesn’t cause everlasting happiness.
  7. The suffering is caused by attachment to desire of objects material or non-material
  8. The religious perspectives on the meaning of life are those ideologies which explain life in terms of an implicit purpose not defined by humans.

For Bahá’i, the purpose of life is spiritual growth and service to humanity. Human beings are viewed as intrinsically spiritual beings. People’s lives in this material world provide extended opportunities to grow, to develop divine qualities and virtues.

True Christians believe the purpose of life is to first become free of sin by understanding and keeping Jesus’ commandments and following his Teachings.

Hindu beliefs that spiritual development occurs across many lifetimes, and goals should match the state of development of the individual. There are four possible aims to human life:

  1. Kāma (wish, desire, love and sensual pleasure),
  2. Artha (wealth, prosperity, glory)
  3. Dharma (righteousness, duty, morality, virtue, ethics, non-violence and truth)
  4. Moksha (liberation from Samsāra, the cycle of reincarnation).

The meaning of life is tied up in the concepts of karma (causal action), sansara (the cycle of birth and rebirth), and moksha (liberation). Existence is conceived as the progression of the ātman (soul) across numerous lifetimes, and its ultimate progression towards liberation from karma.

Hinduism often worships Devas or Guardian Angels (non-physical entities) that watch over us and direct our lives in mysterious ways. They often guide us into Life experiences or goals that we are unaware of but need to occur for the growth of our being.

In Islam, man’s ultimate life objective is to worship Allah  by abiding by the Divine guidelines revealed in the Qur’an and the Tradition of the Prophet. Earthly life is merely a test, determining one’s afterlife, either in Jannat (paradise) or in Jahannum(Hell).

Jainism promotes self-discipline above all else. Through following the ascetic teachings of Jina, a human achieves enlightenment (perfect knowledge). Jainism divides the universe into living and non-living beings. Therefore, happiness is the result of self-conquest and freedom from external objects. The meaning of life is to use the physical body to achieve self-realization and bliss. Jains believe that every human is responsible for his or her actions and all living beings have an eternal soul, jiva. Jains believe all souls are equal because they all possess the potential of being liberated and attaining Moksha. Jains refuse food obtained with unnecessary cruelty to animals.

In Judaism, the meaning of life is to serve or connect with the one true God.

In Mormon theology, the purpose of life is to become more like God.

Sikhism sees the foundation of free will, choosing one’s way, means that life is a creative process. “The Lord dwells in every heart, and every heart has its own way to reach Him.  One can interpret God as the Universe itself. They see life as an opportunity to understand this God as well as to discover the divinity which lies in each individual.

Sufis say the universe exists only for God’s pleasure; Creation is a grand game, wherein Allah is the greatest prize.

Zoroastrians believe in a universe created by a transcendental God. By using free will, people must take an active role in the universal conflict, with good thoughts, good words and good deeds to ensure happiness and to keep chaos at bay.