Anatomically modern humans

Anatomically modern humans

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The term anatomically modern humans (AMH) in paleoanthropology
Paleoanthropology
Paleoanthropology, which combines the disciplines of paleontology and physical anthropology, is the study of ancient humans as found in fossil hominid evidence such as petrifacted bones and footprints.-19th century:...

 refers to early individuals of Homo sapiens with an appearance
Human physical appearance
Human physical appearance refers to the outward phenotype or look of human beings. There are infinite variations in human phenotypes, though society reduces the variability to distinct categories...

 consistent with the range
Human variability
Human variability, or human variation, is the range of possible values for any measurable characteristic, physical or mental, of human beings. Differences can be trivial or important, transient or permanent, voluntary or involuntary, congenital or acquired, genetic or environmental...

 of phenotypes in modern humans.

Anatomically modern humans evolved from archaic Homo sapiens
Archaic Homo sapiens
Archaic Homo sapiens is a loosely defined term used to describe a number of varieties of Homo, as opposed to anatomically modern humans , in the period beginning 500,000 years ago....

 in the Middle Paleolithic
Middle Paleolithic
The Middle Paleolithic is the second subdivision of the Paleolithic or Old Stone Age as it is understood in Europe, Africa and Asia. The term Middle Stone Age is used as an equivalent or a synonym for the Middle Paleolithic in African archeology. The Middle Paleolithic and the Middle Stone Age...

, about 200,000 years ago. The emergence of anatomically modern human marks the dawn of the subspecies Homo sapiens sapiens, i.e. the subspecies of Homo sapiens that includes all modern humans. The oldest fossil remains of anatomically modern humans are the Omo remains
Omo remains
The Omo remains are a collection of hominid bones discovered between 1967 and 1974 at the Kibish sites near the Omo River, Omo National Park in south-western Ethiopia. The bones were recovered by a scientific team from the Kenya National Museums directed by Richard Leakey and others...

 that date to 195,000 years that include two partial skulls as well as arm, leg, foot and pelvis bones.
Other fossils include Homo sapiens idaltu
Homo sapiens idaltu
Homo sapiens idaltu is an extinct subspecies of Homo sapiens that lived almost 160,000 years ago in Pleistocene Africa. is from the Saho-Afar word meaning "elder or first born"....

from Herto in Ethiopia
Ethiopia
Ethiopia , officially known as the Federal Democratic Republic of Ethiopia, is a country located in the Horn of Africa. It is the second-most populous nation in Africa, with over 82 million inhabitants, and the tenth-largest by area, occupying 1,100,000 km2...

 that are 150 kya and remains from Skhul in Israel that are 90,000 years old.

Anatomy



Anatomically modern humans are distinguished from their immediate ancestors, archaic Homo sapiens, by a number of anatomical features. Archaic Homo sapiens had robust skeletons, indicating that they lived a physically demanding life; this may mean that anatomically modern humans, with their more gracile frames, had become more dependent on technology than on raw physical power to meet the challenges of their environment. Archaic Homo sapiens also had very prominent brow ridges (protruding layers of bone above the eye socket). With the emergence of anatomically modern humans, the brow ridges had significantly reduced, and in modern humans they are, on average, barely visible. Another distinguishing feature of AMH is a prominent chin, something which is lacking in archaic Homo sapiens.

AMH commonly have a vertical forehead
Forehead
For the Arsenal striker see GervinhoIn human anatomy, the forehead is the fore part of the head. It is, formally, an area of the head bounded by three features, two of the skull and one of the scalp. The top of the forehead is marked by the hairline, the edge of the area where hair on the scalp...

 whereas their predecessors had foreheads that sloped backwards. According to Desmond Morris
Desmond Morris
Desmond John Morris, born 24 January 1928 in Purton, north Wiltshire, is a British zoologist and ethologist, as well as a popular anthropologist. He is also known as a painter, television presenter and popular author.-Life:...

, the vertical forehead in humans not only houses larger brains, but the prominent forehead plays an important role in human communication through eyebrow
Eyebrow
The eyebrow is an area of thick, delicate hairs above the eye that follows the shape of the lower margin of the brow ridges of some mammals. Their main function is to prevent sweat, water, and other debris from falling down into the eye socket, but they are also important to human communication and...

 movements and forehead skin wrinkling.

Early modern humans



The Omo
Omo remains
The Omo remains are a collection of hominid bones discovered between 1967 and 1974 at the Kibish sites near the Omo River, Omo National Park in south-western Ethiopia. The bones were recovered by a scientific team from the Kenya National Museums directed by Richard Leakey and others...

, Hertho
Homo sapiens idaltu
Homo sapiens idaltu is an extinct subspecies of Homo sapiens that lived almost 160,000 years ago in Pleistocene Africa. is from the Saho-Afar word meaning "elder or first born"....

, Skhul, and Jebel Qafzeh remains are sometimes referred to as "Early Modern Humans" because their skeletal remains exhibit a mix of archaic
Archaic Homo sapiens
Archaic Homo sapiens is a loosely defined term used to describe a number of varieties of Homo, as opposed to anatomically modern humans , in the period beginning 500,000 years ago....

 and modern traits. Skhul V, for example, has prominent brow ridges and a projecting face. However the brain case of Skhul V is distinct from that of the Neanderthals and is similar to the brain case of modern humans.

In Europe, the early modern humans were the Cro-Magnon
Cro-Magnon
The Cro-Magnon were the first early modern humans of the European Upper Paleolithic. The earliest known remains of Cro-Magnon-like humans are radiometrically dated to 35,000 years before present....

.

Origins of modern humans



As it is usually presented, there are two major competing models on this subject - Recent African origin and Multiregional evolution. The debate concerns both the relative amount of replacement or interbreeding that occurred in areas outside of Africa, when waves of humans (or human ancestors) left it to colonize other areas, and the relative importance of more recent waves as opposed to more ancient ones.

The mainstream view, known as the recent African origin model, holds that all or nearly all modern human genetic diversity around the world can be traced back to the first anatomically modern humans to leave Africa. This model is supported by multiple and independent lines of evidence, such as the fossil record and genetics.

Historically, critics of this view are often bracketed together as holding a "multiregional hypothesis", which has waned in popularity since the early 1990s. Such critics argue that significant amounts of older non-African genetic lineages have survived in various parts of the world through inter-breeding with anatomically modern humans. According to strong versions of the multiregional model the various human populations around the world today will have surviving genetic material that goes back as far as early humans such as Homo erectus
Homo erectus
Homo erectus is an extinct species of hominid that lived from the end of the Pliocene epoch to the later Pleistocene, about . The species originated in Africa and spread as far as India, China and Java. There is still disagreement on the subject of the classification, ancestry, and progeny of H...

. A wide set of data in Human evolutionary genetics
Human evolutionary genetics
Human evolutionary genetics studies how one human genome differs from the other, the evolutionary past that gave rise to it, and its current effects. Differences between genomes have anthropological, medical and forensic implications and applications...

 ( Jobling, Hurles and Tyler-Smith, 2004) strongly favour the “Out of Africa
Recent African origin of modern humans
In paleoanthropology, the recent African origin of modern humans is the most widely accepted model describing the origin and early dispersal of anatomically modern humans...

" model. Analyses of modern Europeans suggest that no mitochondrial DNA
Mitochondrial DNA
Mitochondrial DNA is the DNA located in organelles called mitochondria, structures within eukaryotic cells that convert the chemical energy from food into a form that cells can use, adenosine triphosphate...

  (direct maternal line) originating with Neanderthals has survived into modern times. However the recent sequencing of the Neanderthal and Denisovan
Denisova hominin
Denisova hominins , or Denisovans, are Paleolithic-Era members of the genus Homo that may belong to a previously unknown species. In , scientists announced the discovery of a finger bone fragment of a juvenile female that lived about 41,000 years ago, found in Denisova Cave in Altai Krai, Russia, a...

 genomes show some admixture. A draft sequence publication by the Neanderthal Genome Project
Neanderthal Genome Project
The Neanderthal genome project is a collaboration of scientists coordinated by the Max Planck Institute for Evolutionary Anthropology in Germany and 454 Life Sciences in the United States to sequence the Neanderthal genome....

 in May 2010 indicates some form of hybridization between archaic humans and modern humans have taken place after modern humans emerged from Africa. An estimated 1 to 4 percent of the DNA in Europeans and Asians (i.e. French, Chinese and Papua probands) is non-modern, and shared with ancient Neanderthal DNA and not with Sub-Saharan Africans (i.e. Yoruba and San probands). while Melanesians have an additional 1-6% of Denisovan origin.

In practice, controversy is generally about specific periods and specific proposals for periods of such interbreeding. The existence and importance of gene flow
Gene flow
In population genetics, gene flow is the transfer of alleles of genes from one population to another.Migration into or out of a population may be responsible for a marked change in allele frequencies...

 out of Africa is generally accepted, while the possibility of isolated instances of inter-breeding between recent sub-Saharan arrivals and their less "modern" contemporaries at various stages of prehistory is not particularly controversial.

Modern human behavior



There is considerable debate regarding whether the earliest anatomically modern humans behaved similarly to recent or existing humans. Modern human behaviors characteristic of recent humans include fully modern language
Origin of language
The origin of language is the emergence of language in the human species. This is a highly controversial topic. Empirical evidence is so limited that many regard it as unsuitable for serious scholars. In 1866, the Linguistic Society of Paris went so far as to ban debates on the subject...

, the capacity for abstract thought and the use of symbolism to express cultural creativity. There are two opposing hypotheses regarding the origins of modern behavior. Some scholars argue that humans achieved anatomical modernity first, around 200tya, and only later did they adopt modern behaviors around 50tya. This hypothesis is based on the limited record of fossils from periods before 50tya and the abundance of human artifacts found after 50tya. Proponents of this view distinguish "anatomically modern humans" from "behaviorally modern humans".

The opposing view is that humans achieved anatomical and behavioral modernity simultaneously. For example, proponents of this view argue that humans had evolved a lightly built skeleton during the transition to anatomical modernity, and this could have only occurred through increased human cooperation and the increased use of technology, traits characteristic of modern behavior.

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