Neanderthal extinction hypotheses
Encyclopedia
Neanderthal extinction hypotheses are theories
about how Neanderthals became extinct
around 30,000 years ago. Since their discovery, both the Neanderthals' place in the human family tree and their relation to modern Europe
ans has been hotly debated. At different times they have been classified as a separate species (Homo neanderthalensis) and as a subspecies of Homo sapiens (Homo sapiens neanderthalensis).
Theories on the fate of the Neanderthals include an inability to cope with climate change, competitive exclusion
or even genocide
by anatomically modern humans
, and hybridization, effectively being absorbed into the Cro-Magnon
population.
. Inter-stratification of Neanderthal and modern human remains has been suggested, but is disputed.
has suggested a scenario of violent conflict comparable to the genocide
s suffered by indigenous peoples
in recent human history.
history, would be a greater susceptibility on the part of the Neanderthals to pathogen
s introduced by Cro-Magnon
man. Diamond argues that asymmetry in susceptibility to pathogens is a consequence of the difference in lifestyle..
A pandemic will generally have a limited mortality because the pathogen needs a host in order to spread. If two species are similar and lives side by side, then the survival of one species becomes less important for the pathogen. And in the end it may be three outcomes: divergence, exchange of genes, downfall.
A disease that should be mentioned is gonorrhea
. It arose about 200,000 years ago. Along with differences in social and sexual behavior, this sexually transmitted infection could be the cause of the extinction.
on the part of modern humans could account for Neanderthals' replacement by anatomically modern humans on a timescale of 10,000–20,000 years.
The theory that early humans violently replaced Neanderthals was first proposed by French palaeontologist Marcellin Boule (the first person to publish an analysis of a Neanderthal) in 1912.
Another supporter of competitive replacement is Jared Diamond who points out in his book The Third Chimpanzee
that the genocidal replacement of Neanderthals by modern humans is similar to modern human patterns of behavior that occur whenever people with advanced technology invade the territory of less advanced people.
proposed a new explanation for the demise of the Neanderthals. In an article titled "What's a Mother to Do? The Division of Labor among Neanderthals and Modern Humans in Eurasia", they theorize that Neanderthals like Middle paleolithic Homo sapiens did not have a division of labor
between the sexes. Under this hypothesis, both male and female Neanderthals participated in the single main occupation of hunting big game that flourished in Europe in the ice age like bison, deer, gazelles and wild horses. This hypothesis proposes that the Neanderthal's relative lack of labor division resulted in their poor extraction of resources from the environment - as compared to Homo sapiens - and contributes to their demise.
This would have given modern humans a huge advantage in battle. Other researchers, like Yoel Rak, from Tel-Aviv University in Israel
have noted that the fossil records show that Neanderthal pelvis
es in comparison to modern human pelvises would have made it much harder for Neanderthals to absorb shock and to bounce off from one step to the next, giving modern humans another advantage over Neanderthals in running and walking ability.
would descend from Neanderthals, who left Africa at least 350,000 years ago.
The most vocal proponent of the hybridization hypothesis is Erik Trinkaus
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.
Genetic studies indicate some form of hybridization between archaic humans and modern humans had 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 rather than with sub-Saharan Africans (i.e. Yoruba and San probands).
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.
Jordan, in his work Neanderthal, 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 these humans, like Neanderthal, did not have the full capability for throwing spears.
An analysis of a first draft of the Neanderthal genome by Richard E. Green et al. from Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany released in May 2010 indicates interbreeding may have occurred. "Those of us who live outside Africa carry a little Neanderthal DNA in us," said Pääbo, who led the study. "The proportion of Neanderthal-inherited genetic material is about 1 to 4 percent. It is a small but very real proportion of ancestry in non-Africans today," says Dr. David Reich of Harvard Medical School in Boston, who worked on the study. This research compared the genome of the Neanderthals to five modern humans from China, France, sub-Saharan Africa, and Papua New Guinea. The finding is that about 1 to 4 percent of the genes of the non-Africans came from Neanderthals, compared to the baseline defined by the two Africans. This indicates a gene flow from Neanderthals to modern humans, i.e., interbreeding between the two populations. Since the three non-African genomes show a similar proportion of Neanderthal sequences, the interbreeding must have occurred early in the migration of modern humans out of Africa, perhaps in the Middle East
. No evidence for gene flow in the direction from modern humans to Neanderthals was found. The latter result would not be unexpected if contact occurred between a small colonizing population of modern humans and a much larger resident population of Neanderthals. A very limited amount of interbreeding could explain the findings, if it occurred early enough in the colonization process.
While interbreeding is viewed as the most parsimonious interpretation of the genetic discoveries, the authors point out they cannot conclusively rule out an alternative scenario, in which the source population of non-African modern humans was already more closely related to Neanderthals than other Africans were, due to ancient genetic divisions within Africa.
Among the genes shown to differ between present-day humans and Neanderthals were RPTN
, SPAG17, CAN15, TTF1 and PCD16.
, may have contributed to the Neanderthals' decline by reducing their food supply. Studies of sediment layers at Mezmaiskaya Cave
suggest a severe reduction of plant pollen. The damage to plant life would have led to a corresponding decline in plant-eating mammals hunted by the Neanderthals.
Hypothesis
A hypothesis is a proposed explanation for a phenomenon. The term derives from the Greek, ὑποτιθέναι – hypotithenai meaning "to put under" or "to suppose". For a hypothesis to be put forward as a scientific hypothesis, the scientific method requires that one can test it...
about how Neanderthals became extinct
Extinction
In biology and ecology, extinction is the end of an organism or of a group of organisms , normally a species. The moment of extinction is generally considered to be the death of the last individual of the species, although the capacity to breed and recover may have been lost before this point...
around 30,000 years ago. Since their discovery, both the Neanderthals' place in the human family tree and their relation to modern Europe
Europe
Europe is, by convention, one of the world's seven continents. Comprising the westernmost peninsula of Eurasia, Europe is generally 'divided' from Asia to its east by the watershed divides of the Ural and Caucasus Mountains, the Ural River, the Caspian and Black Seas, and the waterways connecting...
ans has been hotly debated. At different times they have been classified as a separate species (Homo neanderthalensis) and as a subspecies of Homo sapiens (Homo sapiens neanderthalensis).
Theories on the fate of the Neanderthals include an inability to cope with climate change, competitive exclusion
Competitive exclusion principle
In ecology, the competitive exclusion principle, sometimes referred to as Gause's law of competitive exclusion or just Gause's law, is a proposition which states that two species competing for the same resources cannot coexist if other ecological factors are constant...
or even genocide
Genocide
Genocide is defined as "the deliberate and systematic destruction, in whole or in part, of an ethnic, racial, religious, or national group", though what constitutes enough of a "part" to qualify as genocide has been subject to much debate by legal scholars...
by 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....
, and hybridization, effectively being absorbed into 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....
population.
Coexistence prior to extinction
Neanderthals and modern humans coexisted in Europe for several thousand years, but the duration of this period is uncertain. Modern humans may have first migrated to Europe 40–43,000 years ago, and Neanderthals may have lived as recently as 24,000 years ago in refugia on the south coast of the Iberian peninsula such as Gorham's CaveGorham's Cave
Gorham's Cave is a natural sea cave in Gibraltar, considered to be one of the last known habitations of the Neanderthals. It is located on the south east face of the Rock of Gibraltar...
. Inter-stratification of Neanderthal and modern human remains has been suggested, but is disputed.
Rapid extinction by violence
Jared DiamondJared Diamond
Jared Mason Diamond is an American scientist and author whose work draws from a variety of fields. He is currently Professor of Geography and Physiology at UCLA...
has suggested a scenario of violent conflict comparable to the genocide
Genocide
Genocide is defined as "the deliberate and systematic destruction, in whole or in part, of an ethnic, racial, religious, or national group", though what constitutes enough of a "part" to qualify as genocide has been subject to much debate by legal scholars...
s suffered by indigenous peoples
Indigenous peoples
Indigenous peoples are ethnic groups that are defined as indigenous according to one of the various definitions of the term, there is no universally accepted definition but most of which carry connotations of being the "original inhabitants" of a territory....
in recent human history.
Rapid extinction by parasites and pathogens
Another possibility raised by Diamond and others, paralleling colonialistColonialism
Colonialism is the establishment, maintenance, acquisition and expansion of colonies in one territory by people from another territory. It is a process whereby the metropole claims sovereignty over the colony and the social structure, government, and economics of the colony are changed by...
history, would be a greater susceptibility on the part of the Neanderthals to pathogen
Pathogen
A pathogen gignomai "I give birth to") or infectious agent — colloquially, a germ — is a microbe or microorganism such as a virus, bacterium, prion, or fungus that causes disease in its animal or plant host...
s introduced by 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....
man. Diamond argues that asymmetry in susceptibility to pathogens is a consequence of the difference in lifestyle..
A pandemic will generally have a limited mortality because the pathogen needs a host in order to spread. If two species are similar and lives side by side, then the survival of one species becomes less important for the pathogen. And in the end it may be three outcomes: divergence, exchange of genes, downfall.
A disease that should be mentioned is gonorrhea
Neisseria gonorrhoeae
Neisseria gonorrhoeae, also known as gonococci , or gonococcus , is a species of Gram-negative coffee bean-shaped diplococci bacteria responsible for the sexually transmitted infection gonorrhea.N...
. It arose about 200,000 years ago. Along with differences in social and sexual behavior, this sexually transmitted infection could be the cause of the extinction.
Competitive replacement
Even a slight competitive advantageNatural selection
Natural selection is the nonrandom process by which biologic traits become either more or less common in a population as a function of differential reproduction of their bearers. It is a key mechanism of evolution....
on the part of modern humans could account for Neanderthals' replacement by anatomically modern humans on a timescale of 10,000–20,000 years.
The theory that early humans violently replaced Neanderthals was first proposed by French palaeontologist Marcellin Boule (the first person to publish an analysis of a Neanderthal) in 1912.
Another supporter of competitive replacement is Jared Diamond who points out in his book The Third Chimpanzee
The Third Chimpanzee
The Third Chimpanzee: The Evolution and Future of the Human Animal is a wide-ranging book by Jared Diamond, professor of geography and physiology at the University of California, Los Angeles , which applies insights from biology, anthropology, and linguistics to questions such as why one species...
that the genocidal replacement of Neanderthals by modern humans is similar to modern human patterns of behavior that occur whenever people with advanced technology invade the territory of less advanced people.
Division of labor
In 2006, two anthropologists of the University of ArizonaUniversity of Arizona
The University of Arizona is a land-grant and space-grant public institution of higher education and research located in Tucson, Arizona, United States. The University of Arizona was the first university in the state of Arizona, founded in 1885...
proposed a new explanation for the demise of the Neanderthals. In an article titled "What's a Mother to Do? The Division of Labor among Neanderthals and Modern Humans in Eurasia", they theorize that Neanderthals like Middle paleolithic Homo sapiens did not have a division of labor
Division of labour
Division of labour is the specialisation of cooperative labour in specific, circumscribed tasks and likeroles. Historically an increasingly complex division of labour is closely associated with the growth of total output and trade, the rise of capitalism, and of the complexity of industrialisation...
between the sexes. Under this hypothesis, both male and female Neanderthals participated in the single main occupation of hunting big game that flourished in Europe in the ice age like bison, deer, gazelles and wild horses. This hypothesis proposes that the Neanderthal's relative lack of labor division resulted in their poor extraction of resources from the environment - as compared to Homo sapiens - and contributes to their demise.
Anatomical differences and running ability
Researchers including Karen L. Steudel of the University of Wisconsin have proposed that because Neanderthals had limbs that were shorter and stockier than those of modern humans, and because of other anatomical differences in their limbs, the primary reason the Neanderthals were not able to survive is related to the fact that they could not run as fast as modern humans, and they would require 30% more energy than modern humans would for running or walking.This would have given modern humans a huge advantage in battle. Other researchers, like Yoel Rak, from Tel-Aviv University in Israel
Israel
The State of Israel is a parliamentary republic located in the Middle East, along the eastern shore of the Mediterranean Sea...
have noted that the fossil records show that Neanderthal pelvis
Pelvis
In human anatomy, the pelvis is the lower part of the trunk, between the abdomen and the lower limbs .The pelvis includes several structures:...
es in comparison to modern human pelvises would have made it much harder for Neanderthals to absorb shock and to bounce off from one step to the next, giving modern humans another advantage over Neanderthals in running and walking ability.
Interbreeding
An alternative to extinction is that Neanderthals were absorbed into the Cro-Magnon population by interbreeding. This would be counter to strict versions of the Recent African Origin, since it would imply that at least part of the genome of EuropeansEuropean ethnic groups
The ethnic groups in Europe are the various ethnic groups that reside in the nations of Europe. European ethnology is the field of anthropology focusing on Europe....
would descend from Neanderthals, who left Africa at least 350,000 years ago.
The most vocal proponent of the hybridization hypothesis is Erik Trinkaus
Erik 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
Lapedo child
The Lapedo child is a complete pre-historical skeleton found in Portugal. In 1998, the discovery of an early Upper Paleolithic human burial at Abrigo do Lagar Velho, by the team led by pre-history archeologist João Zilhão, has provided evidence of early modern humans from the west of the Iberian...
", 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.
Genetic studies indicate some form of hybridization between archaic humans and modern humans had 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 rather than with sub-Saharan Africans (i.e. Yoruba and San probands).
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.
Jordan, in his work Neanderthal, 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 these humans, like Neanderthal, did not have the full capability for throwing spears.
An analysis of a first draft of the Neanderthal genome by Richard E. Green et al. from Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany released in May 2010 indicates interbreeding may have occurred. "Those of us who live outside Africa carry a little Neanderthal DNA in us," said Pääbo, who led the study. "The proportion of Neanderthal-inherited genetic material is about 1 to 4 percent. It is a small but very real proportion of ancestry in non-Africans today," says Dr. David Reich of Harvard Medical School in Boston, who worked on the study. This research compared the genome of the Neanderthals to five modern humans from China, France, sub-Saharan Africa, and Papua New Guinea. The finding is that about 1 to 4 percent of the genes of the non-Africans came from Neanderthals, compared to the baseline defined by the two Africans. This indicates a gene flow from Neanderthals to modern humans, i.e., interbreeding between the two populations. Since the three non-African genomes show a similar proportion of Neanderthal sequences, the interbreeding must have occurred early in the migration of modern humans out of Africa, perhaps in the Middle East
Middle East
The Middle East is a region that encompasses Western Asia and Northern Africa. It is often used as a synonym for Near East, in opposition to Far East...
. No evidence for gene flow in the direction from modern humans to Neanderthals was found. The latter result would not be unexpected if contact occurred between a small colonizing population of modern humans and a much larger resident population of Neanderthals. A very limited amount of interbreeding could explain the findings, if it occurred early enough in the colonization process.
While interbreeding is viewed as the most parsimonious interpretation of the genetic discoveries, the authors point out they cannot conclusively rule out an alternative scenario, in which the source population of non-African modern humans was already more closely related to Neanderthals than other Africans were, due to ancient genetic divisions within Africa.
Among the genes shown to differ between present-day humans and Neanderthals were RPTN
RPTN
RPTN is a gene that encodes repetin.Repetin is an extracellular epidermal matrix protein.It is one of the genes that differ between present-day humans and neandertals....
, SPAG17, CAN15, TTF1 and PCD16.
Climate change
Another hypothesis involves climate change. Although it is believed that Neanderthals had clothing, it has been proposed that failure to adapt their hunting methods caused their extinction when Europe changed into a sparsely vegetated steppe and semi-desert during the last Ice Age. Requiring more energy to move and hunt than their early modern human counterparts, Neanderthals would have been more susceptible to less food being available as a result of climate change. A string of major volcanic eruptions 40,000 years BP, affecting the region between Italy and the Caucasus MountainsCaucasus Mountains
The Caucasus Mountains is a mountain system in Eurasia between the Black Sea and the Caspian Sea in the Caucasus region .The Caucasus Mountains includes:* the Greater Caucasus Mountain Range and* the Lesser Caucasus Mountains....
, may have contributed to the Neanderthals' decline by reducing their food supply. Studies of sediment layers at Mezmaiskaya Cave
Mezmaiskaya cave
Mezmaiskaya Cave is a cave at 44° 10' N 40° 00' E overlooking the right bank of the Sukhoi Kurdzhips in the southern Russian Republic of Adygea, located in the northwestern foothills of the Caucasus Mountains. Preliminary excavations recovered Mousterian artefacts, dated to about 35,000 B.P. and...
suggest a severe reduction of plant pollen. The damage to plant life would have led to a corresponding decline in plant-eating mammals hunted by the Neanderthals.
See also
- List of hominina (hominid) fossils (with images)
- Neanderthals in popular cultureNeanderthals in popular cultureNeanderthals have been portrayed in popular culture including appearances in literature, visual media and comedy, often in unflattering and inaccurate light....
- Quaternary extinction eventQuaternary extinction eventThe Quaternary period saw the extinctions of numerous predominantly larger, especially megafaunal, species, many of which occurred during the transition from the Pleistocene to the Holocene epoch. However, the extinction wave did not stop at the end of the Pleistocene, but continued especially on...
External links
- Hey Good Lookin': Early Humans Dug Neanderthals – audio report by NPRNPRNPR, formerly National Public Radio, is a privately and publicly funded non-profit membership media organization that serves as a national syndicator to a network of 900 public radio stations in the United States. NPR was created in 1970, following congressional passage of the Public Broadcasting...