Neanderthal admixture hypothesis
Encyclopedia
Various theories of Neanderthal admixture in modern human DNA
, i.e. the result of interbreeding of Neanderthal
s and anatomically modern humans
during the Middle Paleolithic
has been debated throughout the 20th century, and in terms of genetics
throughout the 2000s.
In May 2010, the Neanderthal Genome Project
presented preliminary genetic evidence that interbreeding did likely take place and that a small but significant portion of Neanderthal admixture is present in modern non-African populations. The interbreeding hypothesis is a controversially discussed scenario of Neanderthal extinction, the disappearance of Neanderthal
traits
from the fossil record about 30,000 years ago.
suggested that many Europeans bore traces of Neanderthal ancestry, but associated Neanderthal characteristics with primitivism, writing that since they "belong to a stage in the development of the human species, antecedent to the differentiation of any of the existing races, we may expect to find them in the lowest of these races, all over the world, and in the early stages of all races."
In the early twentieth century, Carleton Coon
argued that the Caucasoid race is of dual origin consisting of Upper Paleolithic (mixture of H. sapiens and neanderthalensis) types and Mediterranean (purely H. sapiens) types. He repeated his theory in his 1962 book The Origin of Races.
Stan Gooch
in Personality and Evolution (1973) and The Neanderthal Question (1977) develops a theory of Neanderthal/Cro-Magnon hybridization, based not on an examination of anatomy but of his understanding of modern human psychology and society, which he claimed owes a significant debt to Neanderthal culture. Gooch's theories were dismissed by the academic establishment.
Gooch refined his theory in Cities of Dreams (1989) and The Neanderthal Legacy (2008).
The focus of the debate shifted from the study of anatomy to archaeogenetics
in the 2000s and to the study of ancient DNA
with the Neanderthal Genome Project
, beginning in 2006.
The question of Neanderthal/Cro-Magnon hybridization is reflected in 20th century popular culture, in works such as La Guerre du feu (1911), Dance of the Tiger
(1978, 1980) by Finnish palaeontologist Björn Kurtén
, and the Earth's Children
series by Jean M. Auel
, published from 1980.
in May 2010 indicates that Neanderthals share more genetic lineages with Non-African populations than with African populations. According to the study, this scenario is best explained by gene flow from Neanderthals to modern humans after 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 rather than with Sub-Saharan Africans (i.e. Yoruba and San probands). Though less parsimonious than gene flow, ancient sub-structure in Africa, could account for the higher levels of Neanderthal lineages detected in Eurasians.
No evidence supporting this has been found in mitochondrial DNA
analyses of modern Europeans, suggesting at least that no direct maternal line originating with Neanderthals has survived into modern times.
Variation in microcephalin
, a critical regulator of brain size whose loss-of-function by damaging mutations may also cause primary microcephaly
, was claimed to be the strongest evidence of admixture as of 2007. One type of the gene, known as D, has a high worldwide frequency (~70%), but a young coalescence age to its most recent common ancestor, ~37,000 years ago. The remaining types (non-D) coalesce to ~990,000 years ago, while the separation time between D and non-D is estimated at ~1,100,000 years ago. An evolutionary advantage of D is possible but controversial.
The distribution of the D allele, high outside Africa but low in sub-Saharan Africa (29%), has been suggested to indicate involvement of an archaic Eurasian population, and current estimates of the divergence time between modern humans and Neanderthals based on mitochondrial DNA are in favor of the Neanderthal lineage as the most likely archaic Homo population from which introgression
into the modern human gene pool took place. However, according to Svante Pääbo
, ancient DNA
from Croatian Neanderthal fossils found at Vindija shows that they carried the non-D allele of microcephalin, and there is no evidence for admixture or introgression.
However a study published in May 2010 found that a Neanderthal individual from Mezzena Rockshelter (Monti Lessini, Italy), possessed the ancestral version of D, rather than the derived version which is common among Eurasian populations. The study did not rule out interbreeding between Neanderthals and modern humans, but indicates that the particular DNA sample provides no support to the theory that Neanderthals contributed the derived allele of D to modern humans.
Based on a 2001 study of the gene that results in red-headedness, some commentators speculated that Neanderthals had red hair
and that some red-headed and freckled humans today share some heritage with Neanderthals. A 2007 study analysing Neanderthal DNA found that some Neanderthals were red-haired, but the mutation to the MC1R gene which caused red hair in Neanderthals is not found in modern humans.
There is evidence that some immune related genes are of Neanderthal origin. HLA-C*0702 is common in modern Europeans and Asians but rarely seen in Africans, but is found in Neanderthals. It is thought that this immune gene may have been picked up by humans after leaving Africa to help deal with European diseases that the Neanderthals had evolved defenses for.
of Washington University. Trinkaus claims various fossils as hybrid individuals, including the "child of Lagar Velho", a skeleton found at Lagar Velho in Portugal
dated to about 24,000 years ago.
In a 2006 publication co-authored by Trinkaus, the fossils found in 1952 in the cave of Pestera Muierii, Romania, are likewise claimed as hybrids.
In his work Neanderthal, Paul Jordan points out that without some interbreeding, certain features on some "modern" skulls of Eastern European Cro-Magnon heritage are hard to explain. In another study, researchers have recently found in Peştera Muierilor
, Romania, remains of European humans from years ago who possessed mostly diagnostic "modern" anatomical features, but also had distinct Neanderthal features not present in ancestral modern humans in Africa, including a large bulge at the back of the skull, a more prominent projection around the elbow joint, and a narrow socket at the shoulder joint. Analysis of one skeleton's shoulder showed that these humans, like Neanderthal, did not have the full capability for throwing spears.
The paleontological analysis of modern-human emergence in Europe has been shifting from considerations of the Neanderthals to assessments of the biology and chronology of the earliest modern humans in western Eurasia. This focus, involving morphologically modern humans before 28,000 years ago, shows accumulating evidence that they present a variable mosaic of derived modern human, archaic human, and Neanderthal features. Studies of fossils from the upper levels of the Sima de las Palomas, Murcia
, Spain, dated to 40,000 years ago, establish the late persistence of Neanderthals in Iberia. This reinforces the conclusion that the Neanderthals were not merely swept away by advancing modern humans. In addition, the Palomas Neanderthals variably exhibit a series of modern-human features rare or absent in earlier Neanderthals. Either they were evolving on their own towards the modern-human pattern, or more likely, they had contact with early modern humans around the Pyrenees
. If the latter is the case, it implies that the persistence of the Middle Paleolithic in Iberia was a matter of choice, and not cultural retardation.
Modern-human findings in Abrigo do Lagar Velho, Portugal
, of 24,500 years ago, allegedly featuring Neanderthal admixtures, have been published. However the interpretation of the Portuguese specimen is disputed.
Human genome
The human genome is the genome of Homo sapiens, which is stored on 23 chromosome pairs plus the small mitochondrial DNA. 22 of the 23 chromosomes are autosomal chromosome pairs, while the remaining pair is sex-determining...
, i.e. the result of interbreeding of Neanderthal
Neanderthal
The Neanderthal is an extinct member of the Homo genus known from Pleistocene specimens found in Europe and parts of western and central Asia...
s and anatomically modern humans
Anatomically modern humans
The term anatomically modern humans in paleoanthropology refers to early individuals of Homo sapiens with an appearance consistent with the range of phenotypes in modern humans....
during 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...
has been debated throughout the 20th century, and in terms of genetics
Genetics
Genetics , a discipline of biology, is the science of genes, heredity, and variation in living organisms....
throughout the 2000s.
In May 2010, 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....
presented preliminary genetic evidence that interbreeding did likely take place and that a small but significant portion of Neanderthal admixture is present in modern non-African populations. The interbreeding hypothesis is a controversially discussed scenario of Neanderthal extinction, the disappearance of Neanderthal
Neanderthal
The Neanderthal is an extinct member of the Homo genus known from Pleistocene specimens found in Europe and parts of western and central Asia...
traits
Trait (biology)
A trait is a distinct variant of a phenotypic character of an organism that may be inherited, environmentally determined or be a combination of the two...
from the fossil record about 30,000 years ago.
History
The hypothesis, variously under the names of interbreeding, hybridization, admixture or hybrid-origin theory, has been discussed ever since the discovery of Neanderthal remains in 19th century, though earlier writers believed that Neanderthals were a direct ancestor of modern humans. Thomas HuxleyThomas Huxley
Thomas Henry Huxley PC FRS was an English biologist, known as "Darwin's Bulldog" for his advocacy of Charles Darwin's theory of evolution....
suggested that many Europeans bore traces of Neanderthal ancestry, but associated Neanderthal characteristics with primitivism, writing that since they "belong to a stage in the development of the human species, antecedent to the differentiation of any of the existing races, we may expect to find them in the lowest of these races, all over the world, and in the early stages of all races."
In the early twentieth century, Carleton Coon
Carleton S. Coon
Carleton Stevens Coon, was an American physical anthropologist, Professor of Anthropology at the University of Pennsylvania, lecturer and professor at Harvard, and president of the American Association of Physical Anthropologists.-Biography:Carleton Coon was born in Wakefield, Massachusetts to a...
argued that the Caucasoid race is of dual origin consisting of Upper Paleolithic (mixture of H. sapiens and neanderthalensis) types and Mediterranean (purely H. sapiens) types. He repeated his theory in his 1962 book The Origin of Races.
Stan Gooch
Stan Gooch
Stan Gooch was a British psychologist and author who is probably best known as the proponent of a "hybrid-origin theory" of human evolution.-Total Man:...
in Personality and Evolution (1973) and The Neanderthal Question (1977) develops a theory of Neanderthal/Cro-Magnon hybridization, based not on an examination of anatomy but of his understanding of modern human psychology and society, which he claimed owes a significant debt to Neanderthal culture. Gooch's theories were dismissed by the academic establishment.
Gooch refined his theory in Cities of Dreams (1989) and The Neanderthal Legacy (2008).
The focus of the debate shifted from the study of anatomy to archaeogenetics
Archaeogenetics
Archaeogenetics, a term coined by Colin Renfrew, refers to the application of the techniques of molecular population genetics to the study of the human past. This can involve:*the analysis of DNA recovered from archaeological remains, i.e...
in the 2000s and to the study of ancient DNA
Ancient DNA
Ancient DNA is DNA isolated from ancient specimens. It can be also loosely described as any DNA recovered from biological samples that have not been preserved specifically for later DNA analyses...
with 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....
, beginning in 2006.
The question of Neanderthal/Cro-Magnon hybridization is reflected in 20th century popular culture, in works such as La Guerre du feu (1911), Dance of the Tiger
Dance of the Tiger
Dance of the Tiger is a short novel, published in English in 1980, by palaeontologist Björn Kurtén that deals with the interaction between Neanderthals and Cro-Magnons...
(1978, 1980) by Finnish palaeontologist Björn Kurtén
Björn Kurtén
Björn Olof Lennartson Kurtén was a distinguished vertebrate paleontologist. He belonged to the Swedish-speaking minority in Finland. He was a professor in paleontology at the University of Helsinki from 1972 up to his death in 1988...
, and the Earth's Children
Earth's Children
Earth's Children is a series of speculative alternative historical fiction novels written by Jean M. Auel set circa 30,000 years before present. There are six novels in the series...
series by Jean M. Auel
Jean M. Auel
Jean Marie Auel is an American writer. She is best known for her Earth's Children books, a series of novels set in prehistoric Europe that explores interactions of Cro-Magnon people with Neanderthals...
, published from 1980.
Genetics
A draft sequence publication by the Neanderthal Genome ProjectNeanderthal 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 that Neanderthals share more genetic lineages with Non-African populations than with African populations. According to the study, this scenario is best explained by gene flow from Neanderthals to modern humans after 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 rather than with Sub-Saharan Africans (i.e. Yoruba and San probands). Though less parsimonious than gene flow, ancient sub-structure in Africa, could account for the higher levels of Neanderthal lineages detected in Eurasians.
No evidence supporting this has been found in 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...
analyses of modern Europeans, suggesting at least that no direct maternal line originating with Neanderthals has survived into modern times.
Variation in microcephalin
Microcephalin
Microcephalin is one of six genes causing primary microcephaly when non-functional mutations exist in the homozygous state...
, a critical regulator of brain size whose loss-of-function by damaging mutations may also cause primary microcephaly
Microcephaly
Microcephaly is a neurodevelopmental disorder in which the circumference of the head is more than two standard deviations smaller than average for the person's age and sex. Microcephaly may be congenital or it may develop in the first few years of life...
, was claimed to be the strongest evidence of admixture as of 2007. One type of the gene, known as D, has a high worldwide frequency (~70%), but a young coalescence age to its most recent common ancestor, ~37,000 years ago. The remaining types (non-D) coalesce to ~990,000 years ago, while the separation time between D and non-D is estimated at ~1,100,000 years ago. An evolutionary advantage of D is possible but controversial.
The distribution of the D allele, high outside Africa but low in sub-Saharan Africa (29%), has been suggested to indicate involvement of an archaic Eurasian population, and current estimates of the divergence time between modern humans and Neanderthals based on mitochondrial DNA are in favor of the Neanderthal lineage as the most likely archaic Homo population from which introgression
Introgression
Introgression, also known as introgressive hybridization, in genetics is the movement of a gene from one species into the gene pool of another by the repeated backcrossing of an interspecific hybrid with one of its parent species...
into the modern human gene pool took place. However, according to Svante Pääbo
Svante Pääbo
Svante Pääbo is a Swedish biologist specializing in evolutionary genetics. He was born in 1955 in Stockholm to Sune Bergström, who shared the Nobel Prize in Physiology or Medicine with Bengt I. Samuelsson and John R. Vane in 1982, and his mother, Estonian Karin Pääbo.He earned his PhD from Uppsala...
, ancient DNA
Ancient DNA
Ancient DNA is DNA isolated from ancient specimens. It can be also loosely described as any DNA recovered from biological samples that have not been preserved specifically for later DNA analyses...
from Croatian Neanderthal fossils found at Vindija shows that they carried the non-D allele of microcephalin, and there is no evidence for admixture or introgression.
However a study published in May 2010 found that a Neanderthal individual from Mezzena Rockshelter (Monti Lessini, Italy), possessed the ancestral version of D, rather than the derived version which is common among Eurasian populations. The study did not rule out interbreeding between Neanderthals and modern humans, but indicates that the particular DNA sample provides no support to the theory that Neanderthals contributed the derived allele of D to modern humans.
Based on a 2001 study of the gene that results in red-headedness, some commentators speculated that Neanderthals had red hair
Red hair
Red hair occurs on approximately 1–2% of the human population. It occurs more frequently in people of northern or western European ancestry, and less frequently in other populations...
and that some red-headed and freckled humans today share some heritage with Neanderthals. A 2007 study analysing Neanderthal DNA found that some Neanderthals were red-haired, but the mutation to the MC1R gene which caused red hair in Neanderthals is not found in modern humans.
There is evidence that some immune related genes are of Neanderthal origin. HLA-C*0702 is common in modern Europeans and Asians but rarely seen in Africans, but is found in Neanderthals. It is thought that this immune gene may have been picked up by humans after leaving Africa to help deal with European diseases that the Neanderthals had evolved defenses for.
Anatomy
The most vocal proponent of the hybridization hypothesis on anatomical grounds has been Erik TrinkausErik Trinkaus
Erik Trinkaus, PhD, is a prominent paleoanthropologist and expert on Neanderthal biology and human evolution. Trinkaus researches the evolution of the species Homo sapiens and recent human diversity, focusing on the paleoanthropology and emergence of late archaic and early modern humans, and the...
of Washington University. Trinkaus claims various fossils as hybrid individuals, including the "child of Lagar Velho", a skeleton found at Lagar Velho in Portugal
Portugal
Portugal , officially the Portuguese Republic is a country situated in southwestern Europe on the Iberian Peninsula. Portugal is the westernmost country of Europe, and is bordered by the Atlantic Ocean to the West and South and by Spain to the North and East. The Atlantic archipelagos of the...
dated to about 24,000 years ago.
In a 2006 publication co-authored by Trinkaus, the fossils found in 1952 in the cave of Pestera Muierii, Romania, are likewise claimed as hybrids.
In his work Neanderthal, Paul Jordan points out that without some interbreeding, certain features on some "modern" skulls of Eastern European Cro-Magnon heritage are hard to explain. In another study, researchers have recently found in Peştera Muierilor
Peştera Muierilor
Peștera Muierilor, or Peștera Muierii , is an elaborate cave system located in the Baia de Fier commune, Gorj County, Romania. It contains abundant cave-bear remains, as well as a human skull. The skull is radiocarbon dated to 30,150 ± 800, indication an absolute age between 40,000 and 30,000 BP....
, Romania, remains of European humans from years ago who possessed mostly diagnostic "modern" anatomical features, but also had distinct Neanderthal features not present in ancestral modern humans in Africa, including a large bulge at the back of the skull, a more prominent projection around the elbow joint, and a narrow socket at the shoulder joint. Analysis of one skeleton's shoulder showed that these humans, like Neanderthal, did not have the full capability for throwing spears.
The paleontological analysis of modern-human emergence in Europe has been shifting from considerations of the Neanderthals to assessments of the biology and chronology of the earliest modern humans in western Eurasia. This focus, involving morphologically modern humans before 28,000 years ago, shows accumulating evidence that they present a variable mosaic of derived modern human, archaic human, and Neanderthal features. Studies of fossils from the upper levels of the Sima de las Palomas, Murcia
Murcia
-History:It is widely believed that Murcia's name is derived from the Latin words of Myrtea or Murtea, meaning land of Myrtle , although it may also be a derivation of the word Murtia, which would mean Murtius Village...
, Spain, dated to 40,000 years ago, establish the late persistence of Neanderthals in Iberia. This reinforces the conclusion that the Neanderthals were not merely swept away by advancing modern humans. In addition, the Palomas Neanderthals variably exhibit a series of modern-human features rare or absent in earlier Neanderthals. Either they were evolving on their own towards the modern-human pattern, or more likely, they had contact with early modern humans around the Pyrenees
Pyrenees
The Pyrenees is a range of mountains in southwest Europe that forms a natural border between France and Spain...
. If the latter is the case, it implies that the persistence of the Middle Paleolithic in Iberia was a matter of choice, and not cultural retardation.
Modern-human findings in Abrigo do Lagar Velho, Portugal
Portugal
Portugal , officially the Portuguese Republic is a country situated in southwestern Europe on the Iberian Peninsula. Portugal is the westernmost country of Europe, and is bordered by the Atlantic Ocean to the West and South and by Spain to the North and East. The Atlantic archipelagos of the...
, of 24,500 years ago, allegedly featuring Neanderthal admixtures, have been published. However the interpretation of the Portuguese specimen is disputed.
See also
- Archaic Homo sapiens admixture with modern humansArchaic Homo sapiens admixture with modern humansArchaic Homo sapiens admixture with modern humans is known to occur at least twice: with Neanderthals, and with Denisova hominin. An estimated 1 to 4 percent of the DNA in Europeans and Asians is non-modern, and shared with ancient Neanderthal DNA rather than with Sub-Saharan Africans Archaic Homo...
- Neanderthal Genome ProjectNeanderthal Genome ProjectThe 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....
- Multiregional hypothesis