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Several terms redirect here. Human_sentence_0

For other uses, see Human (disambiguation), Mankind (disambiguation), Humankind (disambiguation), Human Race (disambiguation), Human Being (disambiguation) and Homo sapiens (disambiguation). Human_sentence_1



Temporal range: 0.35–0 Ma PreꞒ O S D C P T J K Pg N

Middle PleistocenePresentHuman_header_cell_0_0_0
Conservation statusHuman_header_cell_0_1_0
Scientific classification HomoHuman_header_cell_0_2_0
Kingdom:Human_cell_0_3_0 AnimaliaHuman_cell_0_3_1
Phylum:Human_cell_0_4_0 ChordataHuman_cell_0_4_1
Class:Human_cell_0_5_0 MammaliaHuman_cell_0_5_1
Order:Human_cell_0_6_0 PrimatesHuman_cell_0_6_1
Suborder:Human_cell_0_7_0 HaplorhiniHuman_cell_0_7_1
Infraorder:Human_cell_0_8_0 SimiiformesHuman_cell_0_8_1
Family:Human_cell_0_9_0 HominidaeHuman_cell_0_9_1
Subfamily:Human_cell_0_10_0 HomininaeHuman_cell_0_10_1
Tribe:Human_cell_0_11_0 HomininiHuman_cell_0_11_1
Genus:Human_cell_0_12_0 HomoHuman_cell_0_12_1
Species:Human_cell_0_13_0 H. sapiensHuman_cell_0_13_1
Binomial nameHuman_header_cell_0_14_0

Humans (Homo sapiens) are a species of highly intelligent primates. Human_sentence_2

They are the only extant members of the subtribe Hominina and—together with chimpanzees, gorillas, and orangutans—are part of the family Hominidae (the great apes, or hominids). Human_sentence_3

Humans are terrestrial animals, characterized by their erect posture and bipedal locomotion; high manual dexterity and heavy tool use compared to other animals; open-ended and complex language use compared to other animal communications; larger, more complex brains than other primates; and highly advanced and organized societies. Human_sentence_4

Several early hominins used fire and occupied much of Eurasia. Human_sentence_5

Early modern humans are thought to have diverged in Africa from an earlier hominin around 300,000 years ago, with the earliest fossil evidence of Homo sapiens also appearing around 300,000 years ago in Africa. Human_sentence_6

Humans began to exhibit evidence of behavioral modernity at least by about 100,000–70,000 years ago (and possibly earlier). Human_sentence_7

In several waves of migration, H. sapiens ventured out of Africa and populated most of the world. Human_sentence_8

The spread of the large and increasing population of humans has profoundly affected the biosphere and millions of species worldwide. Human_sentence_9

Among the key advantages that explain this evolutionary success is the presence of a larger, well-developed brain, which enables advanced abstract reasoning, language, problem solving, sociality, and culture through social learning. Human_sentence_10

Humans use tools more frequently and effectively than any other animal: they are the only extant species to build fires, cook food, clothe themselves, and create and use numerous other technologies and arts. Human_sentence_11

Humans uniquely use systems of symbolic communication such as language and art to express themselves and exchange ideas, as well as to organize themselves into purposeful groups. Human_sentence_12

Humans create complex social structures composed of many cooperating and competing groups, from families and kinship networks to political states. Human_sentence_13

Social interactions between humans have established an extremely wide variety of values, social norms, and rituals, which together undergird human society. Human_sentence_14

Curiosity and the human desire to understand and influence the environment and to explain and manipulate phenomena have motivated humanity's development of science, philosophy, mythology, religion, and other fields of knowledge. Human_sentence_15

Though most of human existence has been sustained by hunting and gathering in band societies, many human societies transitioned to sedentary agriculture approximately 10,000 years ago, domesticating plants and animals, thus enabling the growth of civilization. Human_sentence_16

These human societies subsequently expanded, establishing various forms of government and culture around the world, and unifying people within regions to form states and empires. Human_sentence_17

The rapid advancement of scientific and medical understanding in the 19th and 20th centuries permitted the development of more efficient medical tools and healthier lifestyles, resulting in increased lifespans and causing the human population to rise exponentially. Human_sentence_18

The global human population is about 7.8 billion in 2020. Human_sentence_19

Etymology and definition Human_section_0

Further information: Names for the human species and Human taxonomy Human_sentence_20

Although it can be applied to other members of the genus Homo, in common usage the word "human" generally refers to the only extant species—Homo sapiens. Human_sentence_21

The definition of H. sapiens itself is debated. Human_sentence_22

Some paleoanthropologists include fossils that others have allocated to different species, while the majority assign only fossils that align anatomically with the species as it exists today. Human_sentence_23

The English word "human" is a Middle English loanword from Old French humain, ultimately from Latin hūmānus, the adjectival form of homō ("man" - in the sense of humankind). Human_sentence_24

The native English term man can refer to the species generally (a synonym for humanity) as well as to human males. Human_sentence_25

It may also refer to individuals of either sex, though this latter form is less common in contemporary English. Human_sentence_26

The species binomial "Homo sapiens" was coined by Carl Linnaeus in his 18th-century work Systema Naturae. Human_sentence_27

The generic name "Homo" is a learned 18th-century derivation from Latin homō, which refers to humans of either sex. Human_sentence_28

The species name "sapiens" means "wise", "sapient", "knowledgeable" (Latin sapiens is the singular form, plural is sapientes). Human_sentence_29

Evolution Human_section_1

Main article: Human evolution Human_sentence_30

The genus Homo evolved and diverged from other hominins in Africa several million years ago, after the human clade split from the chimpanzee lineage of the hominids (great apes) branch of the primates. Human_sentence_31

Modern humans, specifically the subspecies Homo sapiens sapiens, proceeded to colonize all the continents and larger islands, arriving in Eurasia 125,000–60,000 years ago, Australia around 40,000 years ago, the Americas around 15,000 years ago, and remote islands such as Hawaii, Easter Island, Madagascar, and New Zealand between the years 300 and 1280. Human_sentence_32

The closest living relatives of humans are chimpanzees and bonobos (genus Pan), as well as gorillas (genus Gorilla). Human_sentence_33

The gibbons (family Hylobatidae) and orangutans (genus Pongo) were the first groups to split from the lineage leading to humans, then gorillas, and finally, chimpanzees. Human_sentence_34

The splitting date between human and chimpanzee lineages is placed 4–8 million years ago, during the late Miocene epoch. Human_sentence_35

During this split, chromosome 2 was formed from the joining of two other chromosomes, leaving humans with only 23 pairs of chromosomes, compared to 24 for the other apes. Human_sentence_36

The earliest fossils that have been proposed as members of the hominin lineage are Sahelanthropus tchadensis, dating from  million years ago; Orrorin tugenensis, dating from  million years ago; and Ardipithecus kadabba, dating to  million years ago. Human_sentence_37

From these early species, the australopithecines arose around  million years ago, diverging into robust (Paranthropus) and gracile (Australopithecus) branches, possibly one of which—such as A. Human_sentence_38 garhi, dating to  million years ago—is a direct ancestor of the genus Homo. Human_sentence_39

The earliest members of Homo evolved around  million years ago. Human_sentence_40

H. habilis has been considered the first species for which there is clear evidence of the use of stone tools. Human_sentence_41

Nonetheless, the brains of H. habilis were about the same size as that of a chimpanzee, and their main adaptation was bipedalism. Human_sentence_42

During the next million years a process of encephalization began, and with the arrival of Homo erectus in the fossil record, cranial capacity had doubled. Human_sentence_43

H. erectus were the first of the hominina to leave Africa, between million years ago. Human_sentence_44

One population, also sometimes classified as a separate species Homo ergaster, stayed in Africa and evolved into Homo sapiens. Human_sentence_45

It is believed that these species were the first to use fire and complex tools. Human_sentence_46

The earliest transitional fossils between H. ergaster/erectus and archaic humans are from Africa, such as Homo rhodesiensis, but seemingly transitional forms have also been found in Dmanisi, Georgia. Human_sentence_47

These descendants of H. erectus spread through Eurasia c. 500,000 years ago, evolving into H. Human_sentence_48 antecessor, H. Human_sentence_49 heidelbergensis and H. Human_sentence_50 neanderthalensis. Human_sentence_51

Fossils of anatomically modern humans that date from the Middle Paleolithic (about 200,000 years ago) include the Omo-Kibish I remains of Ethiopia and the fossils of Herto Bouri, Ethiopia. Human_sentence_52

Earlier remains now classified as early Homo sapiens, such as the Jebel Irhoud remains from Morocco and the Florisbad Skull from South Africa, have been dated to about 300,000 and 259,000 years old respectively. Human_sentence_53

Fossil records of archaic Homo sapiens from Skhul in Israel and Southern Europe begin around 90,000 years ago. Human_sentence_54

Anatomical adaptations Human_section_2

Human evolution is characterized by a number of morphological, developmental, physiological, and behavioral changes that have taken place since the split between the last common ancestor of humans and chimpanzees. Human_sentence_55

The most significant of these adaptations are 1. bipedalism, 2. increased brain size, 3. lengthened ontogeny (gestation and infancy), 4. decreased sexual dimorphism (neoteny). Human_sentence_56

The relationship between all these changes is the subject of ongoing debate. Human_sentence_57

Other significant morphological changes included the evolution of a power and precision grip, a change first occurring in H. erectus. Human_sentence_58

Bipedalism is the basic adaption of the hominin line, and it is considered the main cause behind a suite of skeletal changes shared by all bipedal hominins. Human_sentence_59

The earliest bipedal hominin is considered to be either Sahelanthropus or Orrorin, with Ardipithecus, a full bipedal, coming somewhat later. Human_sentence_60

The knuckle walkers, the gorilla and chimpanzee, diverged around the same time, and either Sahelanthropus or Orrorin may be humans' last shared ancestor with those animals. Human_sentence_61

The early bipedals eventually evolved into the australopithecines and later the genus Homo. Human_sentence_62

There are several theories of the adaptational value of bipedalism. Human_sentence_63

It is possible that bipedalism was favored because it freed up the hands for reaching and carrying food, because it saved energy during locomotion, because it enabled long-distance running and hunting, or as a strategy for avoiding hyperthermia by reducing the surface exposed to direct sun. Human_sentence_64

The human species developed a much larger brain than that of other primates—typically 1,330 cm (81 cu in) in modern humans, over twice the size of that of a chimpanzee or gorilla. Human_sentence_65

The pattern of encephalization started with Homo habilis which at approximately 600 cm (37 cu in) had a brain slightly larger than chimpanzees, and continued with Homo erectus (800–1,100 cm (49–67 cu in)), and reached a maximum in Neanderthals with an average size of 1,200–1,900 cm (73–116 cu in), larger even than Homo sapiens (but less encephalized). Human_sentence_66

The pattern of human postnatal brain growth differs from that of other apes (heterochrony), and allows for extended periods of social learning and language acquisition in juvenile humans. Human_sentence_67

However, the differences between the structure of human brains and those of other apes may be even more significant than differences in size. Human_sentence_68

The increase in volume over time has affected different areas within the brain unequally—the temporal lobes, which contain centers for language processing have increased disproportionately, as has the prefrontal cortex which has been related to complex decision making and moderating social behavior. Human_sentence_69

Encephalization has been tied to an increasing emphasis on meat in the diet, or with the development of cooking, and it has been proposed that intelligence increased as a response to an increased necessity for solving social problems as human society became more complex. Human_sentence_70

The reduced degree of sexual dimorphism is primarily visible in the reduction of the male canine tooth relative to other ape species (except gibbons). Human_sentence_71

Another important physiological change related to sexuality in humans was the evolution of hidden estrus. Human_sentence_72

Humans are the only ape in which the female is intermittently fertile year round, and in which no special signals of fertility are produced by the body (such as genital swelling during estrus). Human_sentence_73

Nonetheless humans retain a degree of sexual dimorphism in the distribution of body hair and subcutaneous fat, and in the overall size, males being around 25% larger than females. Human_sentence_74

These changes taken together have been interpreted as a result of an increased emphasis on pair bonding as a possible solution to the requirement for increased parental investment due to the prolonged infancy of offspring. Human_sentence_75

History Human_section_3

Main article: Human history Human_sentence_76

As early Homo sapiens dispersed, it encountered varieties of archaic humans both in Africa and in Eurasia, in Eurasia notably Homo neanderthalensis. Human_sentence_77

Since 2010, evidence for gene flow between archaic and modern humans during the period of roughly 100,000 to 30,000 years ago has been discovered. Human_sentence_78

This includes modern human admixture in Neanderthals, Neanderthal admixture in all modern humans outside Africa, Denisova hominin admixture in Melanesians as well as admixture from unnamed archaic humans to some Sub-Saharan African populations. Human_sentence_79

The "out of Africa" migration of Homo sapiens took place in at least two waves, the first around 130,000 to 100,000 years ago, the second (Southern Dispersal) around 70,000 to 50,000 years ago, resulting in the colonization of Australia around 65–50,000 years ago, This recent out of Africa migration derived from East African populations, which had become separated from populations migrating to Southern, Central and Western Africa at least 100,000 years earlier. Human_sentence_80

Modern humans subsequently spread globally, replacing archaic humans (either through competition or hybridization). Human_sentence_81

By the beginning of the Upper Paleolithic period (50,000 BP), and likely significantly earlier behavioral modernity, including language, music and other cultural universals had developed. Human_sentence_82

They inhabited Eurasia and Oceania by 40,000 years ago, and the Americas at least 14,500 years ago. Human_sentence_83

Until about 12,000 years ago (the beginning of the Holocene), all humans lived as hunter-gatherers, generally in small nomadic groups known as band societies, often in caves. Human_sentence_84

The Neolithic Revolution (the invention of agriculture) took place beginning about 10,000 years ago, first in the Fertile Crescent, spreading through large parts of the Old World over the following millennia, and independently in Mesoamerica about 6,000 years ago. Human_sentence_85

Access to food surplus led to the formation of permanent human settlements, the domestication of animals and the use of metal tools for the first time in history. Human_sentence_86

Agriculture and sedentary lifestyle led to the emergence of early civilizations (the development of urban development, complex society, social stratification and writing) from about 5,000 years ago (the Bronze Age), first beginning in Mesopotamia. Human_sentence_87

The Scientific Revolution, Technological Revolution and the Industrial Revolution brought such discoveries as imaging technology, major innovations in transport, such as the airplane and automobile; energy development, such as coal and electricity. Human_sentence_88

With the advent of the Information Age at the end of the 20th century, modern humans live in a world that has become increasingly globalized and interconnected. Human_sentence_89

Human population growth and industrialisation has led to environmental destruction and pollution significantly contributing to the ongoing mass extinction of other forms of life called the Holocene extinction, which may be further accelerated by global warming in the future. Human_sentence_90

Habitat and population Human_section_4

Further information: Human migration, Demography, and World population Human_sentence_91

Early human settlements were dependent on proximity to water and—depending on the lifestyle—other natural resources used for subsistence, such as populations of animal prey for hunting and arable land for growing crops and grazing livestock. Human_sentence_92

Modern humans, however, have a great capacity for altering their habitats by means of technology, irrigation, urban planning, construction, deforestation and desertification. Human_sentence_93

Human settlements continue to be vulnerable to natural disasters, especially those placed in hazardous locations and with low quality of construction. Human_sentence_94

Deliberate habitat alteration is often done with the goals of increasing comfort or material wealth, increasing the amount of available food, improving aesthetics, or improving ease of access to resources or other human settlements. Human_sentence_95

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 success of a population. Human_sentence_96

Nonetheless, the manner in which a habitat is altered is often a major determinant in population change. Human_sentence_97

The human body's ability to adapt to different environmental stresses allows humans to acclimatize to a wide variety of temperatures, humidity, and altitudes. Human_sentence_98

As a result, humans are a cosmopolitan species found in almost all regions of the world, including tropical rainforest, arid desert, extremely cold arctic regions, and heavily polluted cities. Human_sentence_99

Most other species are confined to a few geographical areas by their limited adaptability. Human_sentence_100

The human population is not, however, uniformly distributed on the Earth's surface, because the population density varies from one region to another and there are large areas almost completely uninhabited, like Antarctica. Human_sentence_101

Most humans (61%) live in Asia; the remainder live in the Americas (14%), Africa (14%), Europe (11%), and Oceania (0.5%). Human_sentence_102

Within the last century, humans have explored challenging environments such as Antarctica, the deep sea, and outer space. Human_sentence_103

Human habitation within these hostile environments is restrictive and expensive, typically limited in duration, and restricted to scientific, military, or industrial expeditions. Human_sentence_104

Human presence on other celestial bodies has been the case mainly with human-made robotic spacecraft and with humans solely on the Moon, two at a time for brief intervals between 1969 and 1972. Human_sentence_105

Long-term continous human presence in space has been the case in orbit around Earth, uninterrupted since the initial crew of the International Space Station, arriving on 31 October 2000, with peaks of thirteen humans at the same time in space. Human_sentence_106

Since 1800, the human population has increased from one billion to over seven billion. Human_sentence_107

The combined biomass of the carbon of all the humans on Earth in 2018 was estimated at 60 million tons, about 10 times larger than that of all non-domesticated mammals. Human_sentence_108

In 2004, some 2.5 billion out of 6.3 billion people (39.7%) lived in urban areas. Human_sentence_109

Problems for humans living in cities include various forms of pollution and crime, especially in inner city and suburban slums. Human_sentence_110

Both overall population numbers and the proportion residing in cities are expected to increase significantly in the coming decades. Human_sentence_111

Humans have had a dramatic effect on the environment. Human_sentence_112

They are apex predators, being rarely preyed upon by other species. Human_sentence_113

Currently, through land development, combustion of fossil fuels, and pollution, humans are thought to be the main contributor to global climate change. Human_sentence_114

If this continues at its current rate, it is predicted that climate change will wipe out half of all plant and animal species over the next century. Human_sentence_115

Biology Human_section_5

Anatomy and physiology Human_section_6

Main article: Human body Human_sentence_116

Further information: Human physical appearance, Anatomically modern human, and Sex differences in humans Human_sentence_117

Most aspects of human physiology are closely homologous to corresponding aspects of animal physiology. Human_sentence_118

The human body consists of the legs, the torso, the arms, the neck, and the head. Human_sentence_119

An adult human body consists of about 100 trillion (10) cells. Human_sentence_120

The most commonly defined body systems in humans are the nervous, the cardiovascular, the circulatory, the digestive, the endocrine, the immune, the integumentary, the lymphatic, the musculoskeletal, the reproductive, the respiratory, and the urinary system. Human_sentence_121

Humans, like most of the other apes, lack external tails, have several blood type systems, have opposable thumbs, and are sexually dimorphic. Human_sentence_122

The comparatively minor anatomical differences between humans and chimpanzees are largely a result of human bipedalism and larger brain size. Human_sentence_123

One difference is that humans have a far faster and more accurate throw than other animals. Human_sentence_124

Humans are also among the best long-distance runners in the animal kingdom, but slower over short distances. Human_sentence_125

Humans' thinner body hair and more productive sweat glands help avoid heat exhaustion while running for long distances. Human_sentence_126

As a consequence of bipedalism, human females have narrower birth canals. Human_sentence_127

The construction of the human pelvis differs from other primates, as do the toes. Human_sentence_128

A trade-off for these advantages of the modern human pelvis is that childbirth is more difficult and dangerous than in most mammals, especially given the larger head size of human babies compared to other primates. Human_sentence_129

Human babies must turn around as they pass through the birth canal while other primates do not, which makes humans the only species where females usually require help from their conspecifics (other members of their own species) to reduce the risks of birthing. Human_sentence_130

As a partial evolutionary solution, human fetuses are born less developed and more vulnerable. Human_sentence_131

Chimpanzee babies are cognitively more developed than human babies until the age of six months, when the rapid development of human brains surpasses chimpanzees. Human_sentence_132

Apart from bipedalism, humans differ from chimpanzees mostly in smelling, hearing, digesting proteins, brain size, and the ability of language. Human_sentence_133

Humans' brains are about three times bigger than in chimpanzees. Human_sentence_134

More importantly, the brain to body ratio is much higher in humans than in chimpanzees, and humans have a significantly more developed cerebral cortex, with a larger number of neurons. Human_sentence_135

The mental abilities of humans are remarkable compared to other apes. Human_sentence_136

Humans' ability of speech is unique among primates. Human_sentence_137

Humans are able to create new and complex ideas, and to develop technology, which is unprecedented among other organisms on Earth. Human_sentence_138

It is estimated that the worldwide average height for an adult human male is about 171 cm (5 ft 7 in), while the worldwide average height for adult human females is about 159 cm (5 ft 3 in). Human_sentence_139

Shrinkage of stature may begin in middle age in some individuals, but tends to be typical in the extremely aged. Human_sentence_140

Through history human populations have universally become taller, probably as a consequence of better nutrition, healthcare, and living conditions. Human_sentence_141

The average mass of an adult human is 59 kg (130 lb) for females and 77 kg (170 lb) for males. Human_sentence_142

Like many other conditions, body weight and body type is influenced by both genetic susceptibility and environment and varies greatly among individuals. Human_sentence_143

(see obesity) Human_sentence_144

Humans have a density of hair follicles comparable to other apes. Human_sentence_145

However, human body hair is vellus hair, most of which is so short and wispy as to be practically invisible. Human_sentence_146

In contrast (and unusually among species), a follicle of terminal hair on the human scalp can grow for many years before falling out. Human_sentence_147

Humans have about 2 million sweat glands spread over their entire bodies, many more than chimpanzees, whose sweat glands are scarce and are mainly located on the palm of the hand and on the soles of the feet. Human_sentence_148

Humans have the largest number of eccrine sweat glands among species. Human_sentence_149

The dental formula of humans is: Human_sentence_150

Humans have proportionately shorter palates and much smaller teeth than other primates. Human_sentence_151

They are the only primates to have short, relatively flush canine teeth. Human_sentence_152

Humans have characteristically crowded teeth, with gaps from lost teeth usually closing up quickly in young individuals. Human_sentence_153

Humans are gradually losing their third molars, with some individuals having them congenitally absent. Human_sentence_154

Genetics Human_section_7

Main article: Human genetics Human_sentence_155

Further information: Human evolutionary genetics Human_sentence_156

Like most animals, humans are a diploid eukaryotic species. Human_sentence_157

Each somatic cell has two sets of 23 chromosomes, each set received from one parent; gametes have only one set of chromosomes, which is a mixture of the two parental sets. Human_sentence_158

Among the 23 pairs of chromosomes there are 22 pairs of autosomes and one pair of sex chromosomes. Human_sentence_159

Like other mammals, humans have an XY sex-determination system, so that females have the sex chromosomes XX and males have XY. Human_sentence_160

No two humans—not even monozygotic twins—are genetically identical. Human_sentence_161

Genes and environment influence human biological variation in visible characteristics, physiology, disease susceptibility and mental abilities. Human_sentence_162

The exact influence of genes and environment on certain traits is not well understood. Human_sentence_163

Compared to the great apes, human gene sequences—even among African populations—are remarkably homogeneous. Human_sentence_164

On average, genetic similarity between any two humans is 99.5%-99.9%. Human_sentence_165

There is about 2–3 times more genetic diversity within the wild chimpanzee population than in the entire human gene pool. Human_sentence_166

A rough and incomplete human genome was assembled as an average of a number of humans in 2003, and currently efforts are being made to achieve a sample of the genetic diversity of the species (see International HapMap Project). Human_sentence_167

By present estimates, humans have approximately 22,000 genes. Human_sentence_168

The variation in human DNA is very small compared to other species, possibly suggesting a population bottleneck during the Late Pleistocene (around 100,000 years ago), in which the human population was reduced to a small number of breeding pairs. Human_sentence_169

By comparing mitochondrial DNA, which is inherited only from the mother, geneticists have concluded that the last female common ancestor whose genetic marker is found in all modern humans, the so-called mitochondrial Eve, must have lived around 90,000 to 200,000 years ago. Human_sentence_170

The forces of natural selection have continued to operate on human populations, with evidence that certain regions of the genome display directional selection in the past 15,000 years. Human_sentence_171

Life cycle Human_section_8

See also: Childbirth, Life expectancy, and Human development (biology) Human_sentence_172

As with other mammals, human reproduction takes place by internal fertilization via sexual intercourse. Human_sentence_173

Typically the gestation period is 38 weeks (9 months). Human_sentence_174

At this point, most modern cultures recognize the baby as a person entitled to the full protection of the law, though some jurisdictions extend various levels of personhood earlier to human fetuses while they remain in the uterus. Human_sentence_175

Compared with other species, human childbirth is dangerous. Human_sentence_176

Painful labors lasting 24 hours or more are not uncommon and sometimes lead to the death of the mother, the child or both. Human_sentence_177

This is because of both the relatively large fetal head circumference and the mother's relatively narrow pelvis. Human_sentence_178

The chances of a successful labor increased significantly during the 20th century in wealthier countries with the advent of new medical technologies. Human_sentence_179

In contrast, pregnancy and natural childbirth remain hazardous ordeals in developing regions of the world, with maternal death rates approximately 100 times greater than in developed countries. Human_sentence_180

In developed countries, infants are typically 3–4 kg (7–9 lb) in weight and 50–60 cm (20–24 in) in height at birth. Human_sentence_181

However, low birth weight is common in developing countries, and contributes to the high levels of infant mortality in these regions. Human_sentence_182

Both the mother and the father provide care for human offspring, in contrast to other primates, where parental care is mostly restricted to mothers. Human_sentence_183

Helpless at birth, humans continue to grow for some years, typically reaching sexual maturity at 12 to 15 years of age. Human_sentence_184

Females continue to develop physically until around the age of 18, whereas male development continues until around age 21. Human_sentence_185

The human life span can be split into a number of stages: infancy, childhood, adolescence, young adulthood, adulthood and old age. Human_sentence_186

The lengths of these stages, however, have varied across cultures and time periods. Human_sentence_187

Compared to other primates, humans experience an unusually rapid growth spurt during adolescence, where the body grows 25% in size. Human_sentence_188

Chimpanzees, for example, grow only 14%, with no pronounced spurt. Human_sentence_189

The presence of the growth spurt is probably necessary to keep children physically small until they are psychologically mature. Human_sentence_190

Humans are one of the few species in which females undergo menopause and become infertile decades before the end of their lives. Human_sentence_191

All species of non-human apes are capable of giving birth until death. Human_sentence_192

It has been proposed that menopause increases a woman's overall reproductive success by allowing her to invest more time and resources in her existing offspring, and in turn their children (the grandmother hypothesis), rather than by continuing to bear children into old age. Human_sentence_193

Evidence-based studies indicate that the life span of an individual depends on two major factors, genetics and lifestyle choices. Human_sentence_194

For various reasons, including biological/genetic causes, women live on average about four years longer than men. Human_sentence_195

As of 2018, the global average life expectancy at birth of a girl is estimated to be 74.9 years compared to 70.4 for a boy. Human_sentence_196

There are significant geographical variations in human life expectancy, mostly correlated with economic development—for example life expectancy at birth in Hong Kong is 84.8 years for girls and 78.9 for boys, while in Eswatini, primarily because of AIDS, it is 31.3 years for both sexes. Human_sentence_197

The developed world is generally aging, with the median age around 40 years. Human_sentence_198

In the developing world the median age is between 15 and 20 years. Human_sentence_199

While one in five Europeans is 60 years of age or older, only one in twenty Africans is 60 years of age or older. Human_sentence_200

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. Human_sentence_201

Diet Human_section_9

Main article: Human nutrition Human_sentence_202

Humans are omnivorous, capable of consuming a wide variety of plant and animal material. Human_sentence_203

Human groups have adopted a range of diets from purely vegan to primarily carnivorous. Human_sentence_204

In some cases, dietary restrictions in humans can lead to deficiency diseases; however, stable human groups have adapted to many dietary patterns through both genetic specialization and cultural conventions to use nutritionally balanced food sources. Human_sentence_205

The human diet is prominently reflected in human culture, and has led to the development of food science. Human_sentence_206

Until the development of agriculture approximately 10,000 years ago, Homo sapiens employed a hunter-gatherer method as their sole means of food collection. Human_sentence_207

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. Human_sentence_208

It has been proposed that humans have used fire to prepare and cook food since the time of Homo erectus. Human_sentence_209

Around ten thousand years ago, humans developed agriculture, which substantially altered their diet. Human_sentence_210

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. Human_sentence_211

Agriculture led to increased populations, the development of cities, and because of increased population density, the wider spread of infectious diseases. Human_sentence_212

The types of food consumed, and the way in which they are prepared, have varied widely by time, location, and culture. Human_sentence_213

In general, humans can survive for two to eight weeks without food, depending on stored body fat. Human_sentence_214

Survival without water is usually limited to three or four days. Human_sentence_215

About 36 million humans die every year from causes directly or indirectly related to starvation. Human_sentence_216

Childhood malnutrition is also common and contributes to the global burden of disease. Human_sentence_217

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. Human_sentence_218

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." Human_sentence_219

Obesity is caused by consuming more calories than are expended, so excessive weight gain is usually caused by an energy-dense diet. Human_sentence_220

Biological variation Human_section_10

Main article: Human genetic variation Human_sentence_221

There is biological variation in the human species—with traits such as blood type, genetic diseases, cranial features, facial features, organ systems, eye color, hair color and texture, height and build, and skin color varying across the globe. Human_sentence_222

The typical height of an adult human is between 1.4 and 1.9 m (4 ft 7 in and 6 ft 3 in), although this varies significantly depending on sex, ethnic origin, and family bloodlines. Human_sentence_223

Body size is partly determined by genes and is also significantly influenced by environmental factors such as diet, exercise, and sleep patterns. Human_sentence_224

Adult height for each sex in a particular ethnic group approximately follows a normal distribution. Human_sentence_225

There is evidence that populations have adapted genetically to various external factors. Human_sentence_226

The genes that allow adult humans to digest lactose are present in high frequencies in populations that have long histories of cattle domestication and are more dependent on cow milk. Human_sentence_227

Sickle cell anemia, which may provide increased resistance to malaria, is frequent in populations where malaria is endemic. Human_sentence_228

Similarly, populations that have for a long time inhabited specific climates, such as arctic or tropical regions or high altitudes, tend to have developed specific phenotypes that are beneficial for conserving energy in those environments—short stature and stocky build in cold regions, tall and lanky in hot regions, and with high lung capacities at high altitudes. Human_sentence_229

Some populations have evolved highly unique adaptations to very specific environmental conditions, such as those advantageous to ocean-dwelling lifestyles and freediving in the Bajau. Human_sentence_230

Skin color tends to vary clinally and general correlates with the level of ultraviolet radiation in a particular geographic area, with darker skin mostly around the equator. Human_sentence_231

Human skin color can range from darkest brown to lightest peach, or even nearly white or colorless in cases of albinism. Human_sentence_232

Human hair ranges in color from white to red to blond to brown to black, which is the most frequent. Human_sentence_233

Hair color depends on the amount of melanin, with concentrations fading with increased age, leading to grey or even white hair. Human_sentence_234

Most researchers believe that skin darkening is an adaptation that evolved as protection against ultraviolet solar radiation. Human_sentence_235

Light skin pigmentation protects against depletion of vitamin D, which requires sunlight to make. Human_sentence_236

Human skin also has a capacity to darken (tan) in response to exposure to ultraviolet radiation. Human_sentence_237

There is relatively little variation between human geographical populations, and most of the variation that occurs is at the individual level. Human_sentence_238

Of the 0.1%-0.5% of human genetic differentiation, 85% exists within any randomly chosen local population. Human_sentence_239

Genetic data shows that no matter how population groups are defined, two people from the same population group are almost as different from each other as two people from any two different population groups. Human_sentence_240

Current genetic research has demonstrated that human populations native to the African continent are the most genetically diverse. Human_sentence_241

Human genetic diversity decreases in native populations with migratory distance from Africa, and this is thought to be the result of bottlenecks during human migration. Human_sentence_242

Humans have lived in Africa for the longest period of time, but only a part of Africa's population migrated out of the continent into Eurasia, bringing with them just a portion of the original African genetic variety. Human_sentence_243

Non-African populations, however, acquired new genetic inputs from local admixture with archaic populations, and thus have much greater variation from Neanderthals and Denisovans than is found in Africa. Human_sentence_244

African populations also harbour the highest number of private genetic variants, or those not found in other places of the world. Human_sentence_245

While many of the common variants found in populations outside of Africa are also found on the African continent, there are still large numbers which are private to these regions, especially Oceania and the Americas. Human_sentence_246

Furthermore, recent studies have found that populations in sub-Saharan Africa, and particularly West Africa, have ancestral genetic variation which predates modern humans and has been lost in most non-African populations. Human_sentence_247

This ancestry is thought to originate from admixture with an unknown archaic hominin that diverged before the split of Neanderthals and modern humans. Human_sentence_248

The greatest degree of genetic variation exists between males and females. Human_sentence_249

While the nucleotide genetic variation of individuals of the same sex across global populations is no greater than 0.1%-0.5%, the genetic difference between males and females is between 1% and 2%. Human_sentence_250

Males on average are 15% heavier and 15 cm (6 in) taller than females. Human_sentence_251

On average, men have about 40–50% more upper body strength and 20–30% more lower body strength than women. Human_sentence_252

Women generally have a higher body fat percentage than men. Human_sentence_253

Women have lighter skin than men of the same population; this has been explained by a higher need for vitamin D in females during pregnancy and lactation. Human_sentence_254

As there are chromosomal differences between females and males, some X and Y chromosome related conditions and disorders only affect either men or women. Human_sentence_255

After allowing for body weight and volume, the male voice is usually an octave deeper than the female voice. Human_sentence_256

Women have a longer life span in almost every population around the world. Human_sentence_257

Human variation is highly non-concordant: many of the genes do not cluster together and are not inherited together. Human_sentence_258

Skin and hair color are mostly not correlated to height, weight, or athletic ability. Human_sentence_259

Humans do not share the same patterns of variation through geography. Human_sentence_260

Dark-skinned populations that are found in Africa, Australia, and South Asia are not closely related to each other. Human_sentence_261

Individuals with the same morphology do not necessarily cluster with each other by lineage, and a given lineage does not include only individuals with the same trait complex. Human_sentence_262

Due to practices of endogamy, allele frequencies cluster by geographic, national, ethnic, cultural and linguistic boundaries. Human_sentence_263

Despite this, genetic boundaries around local populations do not biologically mark off any fully discrete groups of humans. Human_sentence_264

Much of human variation is continuous, often with no clear points of demarcation. Human_sentence_265

Psychology Human_section_11

Main article: Psychology Human_sentence_266

The human brain, the focal point of the central nervous system in humans, controls the peripheral nervous system. Human_sentence_267

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. Human_sentence_268

These cognitive processes constitute the mind, and, along with their behavioral consequences, are studied in the field of psychology. Human_sentence_269

Humans have a larger and more developed prefrontal cortex than other primates, the region of the brain associated with higher cognition. Human_sentence_270

This has led humans to proclaim themselves to be more intelligent than any other known species. Human_sentence_271

Objectively defining intelligence is difficult, with other animals adapting senses and excelling in areas that humans are unable to. Human_sentence_272

There are some traits that, although not strictly unique, do set humans apart from other animals. Human_sentence_273

Humans may be the only animals who have episodic memory and who can engage in "mental time travel". Human_sentence_274

Even compared with other social animals, humans have an unusually high degree of flexibility in their facial expressions. Human_sentence_275

Humans are the only animals known to cry emotional tears. Human_sentence_276

Humans are one of the few animals able to self-recognize in mirror tests and there is also debate over what extent humans are the only animals with a theory of mind. Human_sentence_277

Sleep and dreaming Human_section_12

Main articles: Sleep and Dream Human_sentence_278

Humans are generally diurnal. Human_sentence_279

The average sleep requirement is between seven and nine hours per day for an adult and nine to ten hours per day for a child; elderly people usually sleep for six to seven hours. Human_sentence_280

Having less sleep than this is common among humans, even though sleep deprivation can have negative health effects. Human_sentence_281

A sustained restriction of adult sleep to four hours per day has been shown to correlate with changes in physiology and mental state, including reduced memory, fatigue, aggression, and bodily discomfort. Human_sentence_282

During sleep humans dream, where they experience sensory images and sounds. Human_sentence_283

Dreaming is stimulated by the pons and mostly occurs during the REM phase of sleep. Human_sentence_284

The length of a dream can vary, from a few seconds up to 30 minutes. Human_sentence_285

Humans have three to five dreams per night, and some may have up to seven; however most dreams are immediately or quickly forgotten. Human_sentence_286

They are more likely to remember the dream if awakened during the REM phase. Human_sentence_287

The events in dreams are generally outside the control of the dreamer, with the exception of lucid dreaming, where the dreamer is self-aware. Human_sentence_288

Dreams can at times make a creative thought occur or give a sense of inspiration. Human_sentence_289

Consciousness and thought Human_section_13

Main articles: Consciousness and Cognition Human_sentence_290

Human consciousness, at its simplest, is "sentience or awareness of internal or external existence". Human_sentence_291

Despite centuries of analyses, definitions, explanations and debates by philosophers and scientists, consciousness remains puzzling and controversial, being "at once the most familiar and most mysterious aspect of our lives". Human_sentence_292

The only widely agreed notion about the topic is the intuition that it exists. Human_sentence_293

Opinions differ about what exactly needs to be studied and explained as consciousness. Human_sentence_294

Some philosophers divide consciousness into phenomenal consciousness, which is experience itself, and access consciousness, which is the processing of the things in experience. Human_sentence_295

It is sometimes synonymous with 'the mind', and at other times, an aspect of it. Human_sentence_296

Historically it is associated with introspection, private thought, imagination and volition. Human_sentence_297

It now often includes some kind of experience, cognition, feeling or perception. Human_sentence_298

It may be 'awareness', or 'awareness of awareness', or self-awareness. Human_sentence_299

There might be different levels or orders of consciousness, or different kinds of consciousness, or just one kind with different features. Human_sentence_300

The process of acquiring knowledge and understanding through thought, experience, and the senses is known as cognition. Human_sentence_301

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. Human_sentence_302

The nature of thought is central to psychology and related fields. Human_sentence_303

Cognitive psychology studies cognition, the mental processes' underlying behavior. Human_sentence_304

Largely focusing on the development of the human mind through the life span, developmental psychology seeks to understand how people come to perceive, understand, and act within the world and how these processes change as they age. Human_sentence_305

This may focus on intellectual, cognitive, neural, social, or moral development. Human_sentence_306

Psychologists have developed intelligence tests and the concept of intelligence quotient in order to assess the relative intelligence of human beings and study its distribution among population. Human_sentence_307

Motivation and emotion Human_section_14

Main articles: Motivation and Emotion Human_sentence_308

Human motivation is not yet wholly understood. Human_sentence_309

From a psychological perspective, Maslow's hierarchy of needs is a well-established theory which can be defined as the process of satisfying certain needs in ascending order of complexity. Human_sentence_310

From a more general, philosophical perspective, human motivation can be defined as a commitment to, or withdrawal from, various goals requiring the application of human ability. Human_sentence_311

Furthermore, incentive and preference are both factors, as are any perceived links between incentives and preferences. Human_sentence_312

Volition may also be involved, in which case willpower is also a factor. Human_sentence_313

Ideally, both motivation and volition ensure the selection, striving for, and realization of goals in an optimal manner, a function beginning in childhood and continuing throughout a lifetime in a process known as socialization. Human_sentence_314

Emotions are biological states associated with the nervous system brought on by neurophysiological changes variously associated with thoughts, feelings, behavioural responses, and a degree of pleasure or displeasure. Human_sentence_315

They are often intertwined with mood, temperament, personality, disposition, creativity, and motivation. Human_sentence_316

Emotion has a significant influence on human behavior and their ability to learn. Human_sentence_317

Acting on extreme or uncontrolled emotions can lead to social disorder and crime, with studies showing criminals usually have a lower emotional intelligence than normal. Human_sentence_318

Emotional experiences perceived as pleasant, such as joy, interest or contentment, contrast with those perceived as unpleasant, like anxiety, sadness, anger, and despair. Human_sentence_319

Happiness, or the state of being happy, is a human emotional condition. Human_sentence_320

The definition of happiness is a common philosophical topic. Human_sentence_321

Some define as experiencing the feeling of positive emotionial affects, while avoiding the negative ones. Human_sentence_322

Others see it as an appraisal of life satisfaction, such as of quality of life. Human_sentence_323

Recent research suggests that being happy might involve experiencing some negative emotions when humans feel they are warranted. Human_sentence_324

Sexuality and love Human_section_15

Main articles: Human sexuality and Love Human_sentence_325

For humans, sexuality involves biological, erotic, physical, emotional, social, or spiritual feelings and behaviors. Human_sentence_326

Because it is a broad term, which has varied with historical contexts over time, it lacks a precise definition. Human_sentence_327

The biological and physical aspects of sexuality largely concern the human reproductive functions, including the human sexual response cycle. Human_sentence_328

Sexuality also affects and is affected by cultural, political, legal, philosophical, moral, ethical, and religious aspects of life. Human_sentence_329

Sexual desire, or libido, is a basic mental state present at the beginning of sexual behavior. Human_sentence_330

Studies show that men desire sex more than women and masturbate more often. Human_sentence_331

Humans can fall anywhere along a continuous scale of sexual orientation, although most humans are heterosexual. Human_sentence_332

While homosexual behavior occurs in many other animals, only humans and domestic sheep have so far been found to exhibit exclusive preference for same-sex relationships. Human_sentence_333

Most evidence supports nonsocial, biological causes of sexual orientation, as cultures that are very tolerant of homosexuality do not have significantly higher rates of it. Human_sentence_334

Research in neuroscience and genetics suggests that other aspects of human sexuality are biologically influenced as well. Human_sentence_335

Love most commonly refers to a feeling of strong attraction or emotional attachment. Human_sentence_336

It can be impersonal (the love of an object, ideal, or strong political or spiritual connection) or interpersonal (love between two humans). Human_sentence_337

Different forms of love have been described, including familial love (love for family), platonic love (love for friends), romantic love (sexual passion) and guest love (hospitality). Human_sentence_338

Romantic love has been shown to elicit brain responses similar to an addiction. Human_sentence_339

When in love dopamine, norepinephrine, serotonin and other chemicals stimulate the brain's pleasure center, leading to side effects such as increased heart rate, loss of appetite and sleep, and an intense feeling of excitement. Human_sentence_340

Culture Human_section_16

Main article: Culture Human_sentence_341

Humanity's unprecedented set of intellectual skills were a key factor in the species' eventual technological advancement and concomitant domination of the biosphere. Human_sentence_342

Disregarding extinct hominids, humans are the only animals known to teach generalizable information, innately deploy recursive embedding to generate and communicate complex concepts, engage in the "folk physics" required for competent tool design, or cook food in the wild. Human_sentence_343

Teaching and learning preserves the cultural and ethnographic identity of all the diverse human societies. Human_sentence_344

Other traits and behaviors that are mostly unique to humans, include starting fires, phoneme structuring and vocal learning. Human_sentence_345

The division of humans into male and female gender roles has been marked culturally by a corresponding division of norms, practices, dress, behavior, rights, duties, privileges, status, and power. Human_sentence_346

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. Human_sentence_347

Gender roles have varied historically, and challenges to predominant gender norms have recurred in many societies. Human_sentence_348

Language Human_section_17

Main article: Language Human_sentence_349

While many species communicate, language is unique to humans, a defining feature of humanity, and a cultural universal. Human_sentence_350

Unlike the limited systems of other animals, human language is open—an infinite number of meanings can be produced by combining a limited number of symbols. Human_sentence_351

Human language also has the capacity of displacement, using words to represent things and happenings that are not presently or locally occurring, but reside in the shared imagination of interlocutors. Human_sentence_352

Language differs from other forms of communication in that it is modality independent; the same meanings can be conveyed through different media, auditively in speech, visually by sign language or writing, and even through tactile media such as braille. Human_sentence_353

Language is central to the communication between humans, and to the sense of identity that unites nations, cultures and ethnic groups. Human_sentence_354

There are approximately six thousand different languages currently in use, including sign languages, and many thousands more that are extinct. Human_sentence_355

Art Human_section_18

Main article: The arts Human_sentence_356

Art is a defining characteristics of humans and there is evidence for a relationship between creativity and language. Human_sentence_357

The earliest evidence of art was shell engravings made by Homo erectus 300,000 years before humans evolved. Human_sentence_358

Human art existed at least 75,000 years ago, with jewellery and drawings found in caves in South Africa. Human_sentence_359

There are various hypothesis's as to why humans have adapted to the arts. Human_sentence_360

These include allowing them to better problem solve issues, providing a means to control or influence other humans, encouraging cooperation and contribution within a society or increasing the chance of attracting a potential mate. Human_sentence_361

The use of imagination developed through art, combined with logic may have given early humans an evolutionary advantage. Human_sentence_362

Evidence of humans engaging in musical activities predates cave art and so far music has been practised by all human cultures. Human_sentence_363

There exists a wide variety of music genres and ethnic musics; with humans musical abilities being related to other abilities, including complex social human behaviours. Human_sentence_364

It has been shown that human brains respond to music by becoming synchronised with the rhythm and beat, a process called entrainment. Human_sentence_365

Dance is also a form of human expression found in all cultures and may have evolved as a way to help early humans communicate. Human_sentence_366

Listening to music and observing dance stimulates the orbitofrontal cortex and other pleasure sensing areas of the brain. Human_sentence_367

Unlike speaking, reading and writing does not come naturally to humans and must be taught. Human_sentence_368

Still literature has been present before the invention of words and language, with 30 000 year old paintings on walls inside some caves portraying a series of dramatic scenes. Human_sentence_369

One of the oldest surviving works of literature is the Epic of Gilgamesh, first engraved on ancient Babylonian tablets about 4,000 years ago. Human_sentence_370

Beyond simply passing down knowledge the use and sharing of imaginative fiction through stories might have helped develop humans capabilities for communication and increased the likelihood of securing a mate. Human_sentence_371

As well as entertainment, storytelling may also have been used as a way to provide the audience with moral lessons and encourage cooperation. Human_sentence_372

Tools and technologies Human_section_19

Main articles: Tool and Technology Human_sentence_373

Stone tools were used by proto-humans at least 2.5 million years ago. Human_sentence_374

The use and manufacture of tools has been put forward as the ability that defines humans more than anything else and has historically been seen as an important evolutionary step. Human_sentence_375

The technology became much more sophisticated about 1.8 million years ago, with the controlled use of fire beginning around 1 million years ago. Human_sentence_376

The development of more complex tools and technologies allowed land to be cultivated and animals to be domesticated, thus proving essential in the development of agriculture—what is known as the Neolithic Revolution. Human_sentence_377

Another wave of technological expansion brought about the Industrial Revolution, where the invention of automated machines brought major changes to humans lifestyles. Human_sentence_378

Throughout history, humans have altered their appearance by wearing clothing. Human_sentence_379

It has been suggested humans started wearing clothing when they migrated north away from Africa's warm climate. Human_sentence_380

Religion and spirituality Human_section_20

Main articles: Religion and Spirituality Human_sentence_381

Religion is generally defined as a belief system concerning the supernatural, sacred or divine, and practices, values, institutions and rituals associated with such belief. Human_sentence_382

Some religions also have a moral code. Human_sentence_383

The evolution and the history of the first religions have recently become areas of active scientific investigation. Human_sentence_384

While no other animals show religious behaviour, the empathy and imagination shown by chimpanzees could be a precursor to the evolution of human religion. Human_sentence_385

While the exact time when humans first became religious remains unknown, research shows credible evidence of religious behaviour from around the Middle Paleolithic era (45-200 thousand years ago). Human_sentence_386

It may have evolved to play a role in helping enforce and encourage cooperation between humans. Human_sentence_387

There is no accepted academic definition of what constitutes religion. Human_sentence_388

Religion has taken on many forms that vary by culture and individual perspective in alignment with the geographic, social, and linguistic diversity of the planet. Human_sentence_389

Religion can include a belief in life after death (commonly involving belief in an afterlife), the origin of life, the nature of the universe (religious cosmology) and its ultimate fate (eschatology), and what is moral or immoral. Human_sentence_390

A common source for answers to these questions are beliefs in transcendent divine beings such as deities or a singular God, although not all religions are theistic. Human_sentence_391

Although the exact level of religiosity can be hard to measure, a majority of humans professes some variety of religious or spiritual belief. Human_sentence_392

In 2015 the majority were Christian followed by Muslims, Hindus and Buddhists, although Islam is growing the most rapidly and likely to overtake Christianity by 2035. Human_sentence_393

In 2015 16% or slightly under 1.2 billion humans are irreligious. Human_sentence_394

This includes humans who have no religious beliefs or do not identify with any religion. Human_sentence_395

Science Human_section_21

Main article: Science Human_sentence_396

An aspect unique to humans is their ability to transmit knowledge from one generation to the next and to continually build on this information to develop tools, scientific laws and other advances to pass on further. Human_sentence_397

This accumulated knowledge can be tested to answer questions or make predictions about how the universe functions and has been very successful in advancing human ascendancy. Human_sentence_398

Historians have identified two major scientific revolutions in human history. Human_sentence_399

The first coincides with the Hellenistic period and the second with the Renaissance. Human_sentence_400

A chain of events and influences led to the development of the scientific method, a process of observation and experimentation that is used to differentiate science from pseudoscience. Human_sentence_401

An understanding of mathematics is unique to humans, although other species of animal have some numerical cognition. Human_sentence_402

All of science can be divided into three major branches, the formal sciences (e.g., logic and mathematics), which are concerned with formal systems, the applied sciences (e.g., engineering, medicine), which are focused on practical applications, and the empirical sciences, which are based on empirical observation and are in turn divided into natural sciences (e.g., physics, chemistry, biology) and social sciences (e.g., psychology, economics, sociology). Human_sentence_403

Philosophy Human_section_22

Main article: Philosophy Human_sentence_404

Philosophy is a field of study where humans seek to understand fundamental truths about themselves and the world in which they live. Human_sentence_405

Philosophical inquiry has been a major feature in the development of humans intellectual history. Human_sentence_406

It has been described as the "no man’s land" between the definitive scientific knowledge and the dogmatic religious teachings. Human_sentence_407

Philosophy relies on reason and evidence unlike religion, but does not require the empirical observations and experiments provided by science. Human_sentence_408

Major fields of philosophy include metaphysics, epistemology, rationality, and axiology (which includes ethics and aesthetics). Human_sentence_409

Society Human_section_23

Main article: Society Human_sentence_410

Society is the system of organizations and institutions arising from interaction between humans. Human_sentence_411

Humans are highly social beings and tend to live in large complex social groups. Human_sentence_412

They can be divided into different groups according to their income, wealth, power, reputation and other factors. Human_sentence_413

The structure of social stratification and the degree of social mobility differs, especially between modern and traditional societies. Human_sentence_414

Human groups range from the size of families to nations. Human_sentence_415

The first forms of human social organization were families living in band societies as hunter-gatherers. Human_sentence_416

Kinship Human_section_24

Main article: Kinship Human_sentence_417

All human societies organize, recognize and classify types of social relationships based on relations between parents, children and other descendants (consanguinity), and relations through marriage (affinity). Human_sentence_418

There is also a third type applied to godparents or adoptive children (fictive). Human_sentence_419

These culturally defined relationships are refereed to as kinship. Human_sentence_420

In many societies it is one of the most important social organizing principle and plays a role in transmitting status and inheritance. Human_sentence_421

All societies have rules of incest taboo, according to which marriage between certain kinds of kin relations are prohibited and some also have rules of preferential marriage with certain kin relations. Human_sentence_422

Ethnicity Human_section_25

Main article: Ethnic group Human_sentence_423

Human ethnic groups are a social category who identify together as a group based on shared attributes that distinguish them from other groups. Human_sentence_424

These can be a common set of traditions, ancestry, language, history, society, culture, nation, religion, or social treatment within their residing area. Human_sentence_425

Ethnicity is separate from the concept of race, which is based on physical characteristics, although both are socially constructed. Human_sentence_426

Assigning ethnicity to certain population is complicated as even within common ethnic designations there can be a diverse range of subgroups and the makeup of these ethnic groups can change over time at both the collective and individual level. Human_sentence_427

Also there is no generally accepted definition on what constitutes an ethnic group. Human_sentence_428

Ethnic groupings can play a powerful role in the social identity and solidarity of ethno-political units. Human_sentence_429

This has been closely tied to the rise of the nation state as the predominant form of political organization in the 19th and 20th centuries. Human_sentence_430

Government and politics Human_section_26

Main articles: Government and Politics Human_sentence_431

The early distribution of political power was determined by the availability of fresh water, fertile soil, and temperate climate of different locations. Human_sentence_432

As farming populations gathered in larger and denser communities, interactions between these different groups increased. Human_sentence_433

This led to the development of governance within and between the communities. Human_sentence_434

As communities got bigger the need for some form of governance increased, as all large societies without a government have struggled to function. Human_sentence_435

Humans have evolved the ability to change affiliation with various social groups relatively easily, including previously strong political alliances, if doing so is seen as providing personal advantages. Human_sentence_436

This cognitive flexibility allows individual humans to change their political ideologies, with those with higher flexibility less likely to support authoritarian and nationalistic stances. Human_sentence_437

Governments create laws and policies that affect the citizens that they govern. Human_sentence_438

There have been multiple forms of government throughout human history, each having various means of obtaining power and ability to exert diverse controls on the population. Human_sentence_439

As of 2017, more than half of all national governments are democracies, with 13% being autocracies and 28% containing elements of both. Human_sentence_440

Many countries have formed international political alliances, the largest being the United Nations with 193 member states. Human_sentence_441

Trade and economics Human_section_27

Main articles: Trade and Economics Human_sentence_442

Trade, the voluntary exchange of goods and services, is seen as a characteristic that differentiates humans from other animals and has been cited as a practice that gave Homo sapiens a major advantage over other hominids. Human_sentence_443

Evidence suggests early H. sapiens made use of long-distance trade routes to exchange goods and ideas, leading to cultural explosions and providing additional food sources when hunting was sparse, while such trade networks did not exist for the now extinct Neanderthals. Human_sentence_444

Early trade likely involved materials for creating tools like obsidian. Human_sentence_445

The first truly international trade routes were around the spice trade through the roman and medieval periods. Human_sentence_446

Other important trade routes to develop around this time include the Silk Road, Incense Route, Amber road, Tea Horse Road, Salt Route, Trans-Saharan Trade Route and the Tin Route. Human_sentence_447

Early human economies were more likely to be based around gift giving instead of a bartering system. Human_sentence_448

Early money consisted of commodities; the oldest being in the form of cattle and the most widely used being cowrie shells. Human_sentence_449

Money has since evolved into governmental issued coins, paper and electronic money. Human_sentence_450

Human study of economics is a social science that looks at how societies distribute scarce resources among different people. Human_sentence_451

There are massive inequalities in the division of wealth among humans; the eight richest humans are worth the same monetary value as the poorest half of all the human population. Human_sentence_452

War Human_section_28

Main article: War Human_sentence_453

Humans willingness to kill other members of their species en masse though organised conflict has long been the subject of debate. Human_sentence_454

One school of thought is that it has evolved as a means to eliminate competitors and has always been an innate human characteristic. Human_sentence_455

The other suggests that war is a relatively recent phenomenon and appeared due to changing social conditions. Human_sentence_456

While not settled the current evidence suggests warlike predispositions only became common about 10,000 years ago, and in many places much more recently than that. Human_sentence_457

War has had a high cost on human life; it is estimated that during the 20th century, between 167 million and 188 million people died as a result of war. Human_sentence_458

See also Human_section_29


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