Humans (Homo sapiens, meaning or ) are the most abundant and widespread species of primates, characterized by bipedalism, minimal body hair, and large, complex brains enabling the development of advanced technology, culture, and language. Humans are highly social beings and tend to live in complex social structures composed of many cooperating and competing groups, from families and kinship networks to political states. Social interactions between humans have established a wide variety of values, social norms, and rituals, which bolster human society. Curiosity and the human desire to understand and influence the environment have motivated humanity's development of art, science, philosophy, religion, mythology, and other fields of knowledge.
Humans have a large and highly developed prefrontal cortex, the region of the brain associated with higher cognition. They are intelligent beings, capable of episodic memory, flexible facial expressions, self-awareness and a theory of mind. The human mind is capable of introspection (metacognition), private thought, imagination, volition, and forming views on existence. Humans can also mentally travel through time (chronesthesia), which signifies episodic foresight. These attributes have allowed them to achieve large technological advancements through reason and the transmission of knowledge to future generations. In anthropology, the cumulative preservation and advancement of knowledge across generations is known as the ratchet effect.
Humans are omnivorous, capable of consuming a wide variety of plant and animal material, and have used fire to prepare and cook food. They can survive for up to eight weeks without food, and three or four days without water. Humans are generally diurnal, sleeping on average seven to nine hours per day. Human childbirth is dangerous, with a high risk of complications and death. Both the mother and the father typically provide care for human offspring, who are helpless at birth.
Genes and the environment influence human biological variation in appearance, physiology, immune system, mental abilities, body size, and lifespan. Though humans vary in many traits, any two humans are on average over 99% genetically similar, with the most genetically diverse populations from Africa. The greatest degree of genetic variation exists between males and females. The genetic difference between males and females is around 1% to 2%. On average, males have greater body strength and females generally have a higher body fat percentage. Females undergo menopause and become infertile potentially decades before the end of their lives. They also have a longer life span in almost every population around the world. The division into male and female gender roles has varied historically, and challenges to predominant gender norms have recurred in many societies.
Humans evolved from other hominins in Africa several million years ago. Although some scientists equate humans with all members of the genus Homo, in common usage it generally refers to Homo sapiens, the only extant member. Homo sapiens emerged around 300,000 years ago and migrated out of Africa, gradually replacing local populations of archaic humans. Early humans were hunter-gatherers, before the invention of agriculture and domestication of animals led to permanent settlement in the Fertile Crescent and other cradles of civilization. As food surpluses enabled populations to become larger and denser, forms of governance developed, the use of writing became necessary, and a number of civilizations rose and fell. Humans have continued to expand, with over 8.3 billion humans occupying almost all regions of Earth in 2026, and have even visited the Moon. This expansion, combined with industrialization, has led to environmental destruction and pollution that significantly contributes to the ongoing mass extinction of many other forms of life.
Etymology and definition
All modern humans are classified into the species Homo sapiens, coined by Carl Linnaeus in his 1735 work Systema Naturae. The generic name Homo is a learned 18th-century derivation from Latin , which refers to humans of either sex. The word human can refer to all members of the Homo genus. The name Homo sapiens means 'wise man' or 'knowledgeable man'. There is disagreement about whether certain extinct members of the genus, namely Neanderthals, should be included as a separate species of humans or as a subspecies of H. sapiens.
Human is a loanword of Middle English from Old French , ultimately from Latin , the adjectival form of ('man' – in the sense of humanity). The native English term man can refer to the species generally (a synonym for humanity) as well as to human males. It may also refer to individuals of either sex.
Although the word animal is colloquially used as an antonym for human, and contrary to a common biological misconception, humans are animals. The word person is often used interchangeably with human, but philosophical debate exists as to whether personhood applies to all humans or all sentient beings, and further if a human can lose personhood (such as by going into a persistent vegetative state) and what the beginning of human personhood is.
Evolution
Humans belong to the biological family of great apes (family Hominidae, superfamily Hominoidea). The lineage of apes that eventually gave rise to humans first split from gibbons (family Hylobatidae), next orangutans (genus Pongo), then gorillas (genus Gorilla), and finally, chimpanzees and bonobos (genus Pan). The last split, between the human and chimpanzee–bonobo lineages, took place around 4-8 million years ago, in the late Miocene epoch. During this split, chromosome 2 was formed in humans from the joining of two other chromosomes, leaving humans with only 23 pairs of chromosomes, compared to 24 for the other apes. Following their split with chimpanzees and bonobos, the hominins diversified into many species and at least two distinct genera. All but one of these lineages – representing the genus Homo and its sole extant species Homo sapiens – are now extinct.
The genus Homo evolved from Australopithecus. Though fossils from the transition are scarce, the earliest members of Homo share several key traits with Australopithecus. Due to the scant available evidence, the time of the divergence to the genus Homo does not have a consensus. Some studies using molecular clock techniques estimate the Homo genus appeared 4.30–2.56 million years ago, while others contest that some early Homo species are incorrectly included in the genus and therefore put this estimate at about 1.87 million years ago.
The earliest record of Homo is the 2.8 million-year-old specimen LD 350-1 from Ethiopia, and the earliest named species are Homo habilis and Homo rudolfensis, which evolved by 2.3 million years ago. H. erectus (the African variant is sometimes called H. ergaster) evolved 2 million years ago and was the first archaic human species to leave Africa and disperse across Eurasia. H. erectus also was the first to evolve a characteristically human body plan. Homo sapiens emerged in Africa at least 300,000 years ago from a species commonly designated as either H. heidelbergensis or H. rhodesiensis, the descendants of H. erectus that remained in Africa. H. sapiens migrated out of the continent, gradually replacing or interbreeding with local populations of archaic humans. Humans began exhibiting behavioral modernity about 160,000–70,000 years ago, and possibly earlier. This development was likely selected amidst natural climate change in Middle to Late Pleistocene Africa.
The "out of Africa" migration 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. H. sapiens proceeded to colonize all the continents and larger islands except Antarctica, arriving in Eurasia 125,000 years ago, Australia around 65,000 years ago, the Americas around 15,000 years ago, and remote islands such as Hawaii, Easter Island, Madagascar, and New Zealand in the years 300 to 1280 CE.
Human evolution was not a simple linear or branched progression but involved interbreeding between related species. Genomic research has shown that hybridization between substantially diverged lineages was common in human evolution. DNA evidence suggests that several genes of Neanderthal origin are present among all non-sub-Saharan African populations, and Neanderthals and other hominins, such as Denisovans, may have contributed up to 6% of their genome to present-day non-sub-Saharan African humans.
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. The most significant of these adaptations are hairlessness, obligate bipedalism, increased brain size, and decreased sexual dimorphism (neoteny). The relationship between all these changes is the subject of ongoing debate.
History
Prehistory
Until about 12,000 years ago, all humans lived as hunter-gatherers. The Neolithic Revolution (the invention of agriculture) first took place in Southwest Asia and spread through large parts of the Old World over the following millennia. It also occurred independently in Mesoamerica (about 6,000 years ago), China, Papua New Guinea, and the Sahel and West Savanna regions of Africa.
The formation of permanent human settlements, the domestication of animals, and the use of metal tools were followed by a permanent food surplus, for the first time in history. Agriculture and a sedentary lifestyle led to the emergence of early civilizations.
Ancient
An urban revolution took place in the 4th millennium BCE with the development of city-states, particularly Sumerian cities located in Mesopotamia. It was in these cities that the earliest known form of writing, cuneiform script, appeared around 3000 BCE. Other major civilizations to develop around this time were Ancient Egypt and the Indus Valley Civilization. They eventually traded with each other and invented technology such as wheels, plows and sails. Emerging by 3000 BCE, the Caral–Supe civilization is the oldest complex civilization in the Americas. Astronomy and mathematics were also developed, and the Great Pyramid of Giza was built. There is evidence of a severe drought lasting about a hundred years that may have caused the decline of these civilizations, with new ones appearing in the aftermath. Babylonians came to dominate Mesopotamia while others—such as the Poverty Point culture, Minoans, and the Shang dynasty—rose to prominence in new areas. The Late Bronze Age collapse around 1200 BCE resulted in the disappearance of a number of civilizations and the beginning of the Greek Dark Ages. During this period iron started replacing bronze, leading to the Iron Age.
In the 5th century BCE, history started being recorded as a discipline, which provided a much clearer picture of life at the time. Between the 8th and 6th centuries BCE, Europe entered the classical antiquity age, a period when ancient Greece and ancient Rome flourished. Around this time, other civilizations also came to prominence. The Maya civilization started to build cities and create complex calendars. In Africa, the Kingdom of Aksum overtook the declining Kingdom of Kush and facilitated trade between India and the Mediterranean. In West Asia, the Achaemenid Empire's system of centralized governance became the precursor to many later empires, while the Gupta Empire in India and the Han dynasty in China have been described as golden ages in their respective regions.
Post-classical