Humans (Homo sapiens), the only living members of the genus Homo, are mammals of the primate order originally from Africa, where they reached anatomical modernity about 200,000 years ago and began to exhibit full behavioral modernity around 50,000 years ago.
The human lineage diverged from its last common ancestor with its closest living relative, the chimpanzee, some 5 million years ago in Africa, evolving into the Australopithecines and eventually the genus Homo. The first homo species to move out of Africa was Homo erectus, the African variety of which, together with Homo heidelbergensis, is considered to be the immediate ancestor of modern humans. Homo sapiens proceeded to colonize the continents, 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 AD and 1280 AD. Around 10,000 years ago humans began to practice sedentary agriculture domesticating plants and animals which allowed for a drastic increase in population worldwide. With the development of fuel-driven technologies and new techniques for health improvement in the 19th and 20th centuries, human populations rose even more. With individuals widespread in every continent except Antarctica, humans are a cosmopolitan species. By 2012, the human population was estimated to be between 6.97 and 7 billion.
Humans are characterized by having a largebrain relative to body size, with a particularly well developed neocortex, prefrontal cortex and temporal lobes, making them capable of abstract reasoning, language, introspection, problem solving and culture through social learning. This mental capability, combined with the adaptation to bipedal locomotion that frees the hands for manipulating objects, has allowed humans to make far greater use of tools than any other living species on Earth. Humans are the only extant species known to build fires and cook their food, as well as the only known species to clothe themselves and create and use numerous other technologies and arts. The study of humans is the scientific discipline of anthropology.
Humans are uniquely adept at utilizing systems of symbolic communication such as language for self-expression, the exchange of ideas, and organization. Humans create complex social structures composed of many cooperating and competing groups, from families and kinship networks to states. Social interactions between humans have established an extremely wide variety of values, social norms, and rituals, which together form the basis of human society. Humans are noted for their desire to understand and influence their environment, seeking to explain and manipulate phenomena through science, philosophy, mythology, and religion.
Etymology and definition
Further information: Man (word) and List of alternative names for the human species
With the discovery and study of fossil ancestors of modern humans the meaning of the word "human" changed, as the previously clear boundary between human and ape blurred, now encompassing multiple species. Today in scientific usage "human" may refer to any member of the genus Homo. Furthermore within Homo sapiens, there is a distinction between anatomically modern Homo sapiens and Archaic Homo sapiens, the earliest fossil members of the species. Sometimes groups such as the Neanderthals are classified as a subspecies of Homo sapiens - Homo sapiens neanderthalensis. However, in everyday usage, and in this article, the word "human" generally refers to the only extant species of the genus - anatomically and behaviorally modern Homo sapiens. The open question about possible extinct subspecies will be briefly covered. Fossil humans are covered in the article "Homo", and in the articles about individual species of the genus.
The English adjective human is a Middle Englishloanword from Old Frenchhumain, ultimately from Latinhūmānus, the adjective form of homō "man". The word's use as a noun (with a plural: humans) dates to the 16th century. The native English term man can refer to the species generally (a synonym for mankind), and could formerly refer to specific individuals of either sex. The latter use is now obsolete. Generic uses of the term "man" are declining, in favor of reserving it for referring specifically to adult males. The word is from Proto-Germanic*mannaz, from a Proto-Indo-European (PIE) root *man-.
The species binomialHomo sapiens was coined by Carl Linnaeus in his 18th century work Systema Naturae, and he himself is the lectotype specimen.[18] The generic nameHomo is a learned 18th century derivation from Latin homō "man", ultimately "earthly being" (Old Latinhemō, a cognate to Old English guma "man", from PIE*dʰǵʰemon-, meaning 'earth' or 'ground'). The species-name sapiens means "wise" or "sapient".
History
Evolution
Main article: Human evolution
Further information: Anthropology, Homo (genus), and Timeline of human evolution
Scientific study of human evolution studies the development of the genus Homo, reconstructing the evolutionary divergence of the human lineage from other hominins (shared ancestors of humans and chimpanzees), hominids (great apes) and primates. "Modern humans" are defined as belonging to the speciesHomo sapiens, specifically to the single extant subspeciesHomo sapiens sapiens.
Evidence from molecular biology
Family tree showing the extant hominoids: humans (genus Homo), chimpanzees and bonobos (genus Pan), gorillas (genus Gorilla), orangutans (genus Pongo), and gibbons (four genera of the family Hylobatidae: Hylobates, Hoolock, Nomascus, and Symphalangus). All except gibbons are hominids.
The closest living relatives of humans are gorillas and chimpanzees. With the sequencing of both the Human and Chimpanzee genome, current estimates of similarity between human and chimpanzee DNA sequences range between 95% and 99%.By using the technique called a molecular clock which estimates the time required for the number of divergent mutations to accumulate between two lineages, the approximate date for the split between lineages can be calculated. The gibbons (hylobatidae) and orangutans ( genus Pongo) were the first groups to split from the line leading to the humans, then gorillas (genus gorilla) followed by the chimpanzees and bonobos (genus Pan). The splitting date between human and Chimpanzee lineages is placed around 4-8 million years ago during the late Miocene epoch.
Evidence from the fossil record
Skulls of 1. Gorilla 2. Australopithecus 3. Homo erectus 4. Neanderthal (La Chapelle aux Saints) 5. Steinheim Skull (Archaic Homo sapiens) 6. Anatomically modern Homo sapiens
There is little fossil evidence for the divergence of the gorilla, chimpanzee and hominin lineages.[26][27] The earliest fossils that have been proposed as members of the hominin lineage are Sahelanthropus tchadensis dating from 7 million years ago, and Orrorin tugenensis dating from 5.7 million years ago and Ardipithecus kadabba dating to 5.6 million years ago. Each of these have been argued to be a bipedal ancestor of later hominins, but in each cases the claims have been contested. It is also possible that either of these species are ancestors of another branch of African apes, or that they represent a shared ancestor between hominins and other apes. The question of the relation between these early fossil species and the hominin lineage is still to be resolved. From these early species the Australopithecines arose around 4 million years ago diverged into robust (also called Paranthropus) and gracile branches, one of which (possibly A. garhi) went on to become ancestors of the genus Homo.
The earliest members of the genus Homo are Homo habilis which evolved around 2.3 million years ago. Homo habilis is the first species for which we have positive evidence of use of stone tools. The brains of these early hominins were about the same size as that of a chimpanzee, and their main adaptation was bipedalism as an adaptation to terrestrial living. 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. Homo erectus were the first of the hominina to leave Africa, and these species spread through Africa, Asia, and Europe between 1.3 to 1.8 million years ago. One population of H. erectus, also sometimes classified as a separate species Homo ergaster, stayed in Africa and evolved into Homo sapiens. It is believed that these species were the first to use fire and complex tools. The earliest transitional fossils between H. ergaster/erectus and '' Archaic H. sapiens are from Africa such as Homo rhodesiensis, but seemingly transitional forms are also found at Dmanisi, Georgia. These descendants of African H. erectus spread through Eurasia from ca. 500,000 years ago evolving into H. antecessor, H. heidelbergensis and H. neanderthalensis. The earliest fossils of Anatomically modern humans are from the Middle Paleolithic, about 200,000 years ago such as the Omo remains of Ethiopia, later fossils from Skhul in Israel and Southern Europe begin around 90,000 years ago.
Reconstruction of Homo habilis, the first human ancestor to use stone tools.
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 1. bipedalism, 2. increased brain size, 3. lengthened ontogeny (gestation and infancy), 4. decreased sexual dimorphism. The relationship between all these changes is the subject of ongoing debate. Other significant morphological changes included the evolution of a power and precision grip, a change first occurring H. erectus.
An array of Neolithic artifacts, including bracelets, axe heads, chisels, and polishing tools.
The automobile revolutionized personal transportation.
Stone tools were used by proto-humans at least 2.5 million years ago. The controlled use of fire began around 1.5 million years ago. Since then, humans have made major advances, developing complex technology to create tools to aid their lives and allowing for other advancements in culture. Major leaps in technology include the discovery of agriculture – what is known as the Neolithic Revolution, and the invention of automated machines in the Industrial Revolution.
Archaeology attempts to tell the story of past or lost cultures in part by close examination of the artifacts they produced. Early humans left stone tools, pottery, and jewelry that are particular to various regions and times.
