Language

Language driven by culture, not biology

20 January 2009

Language in humans has evolved culturally rather than genetically, according to a study by UCL (University College London) and US researchers. By modelling the ways in which genes for language might have evolved alongside language itself, the study showed that genetic adaptation to language would be highly unlikely, as cultural conventions change much more rapidly than genes. Thus, the biological machinery upon which human language is built appears to predate the emergence of language.

According to a phenomenon known as the Baldwin effect, characteristics that are learned or developed over a lifespan may become gradually encoded in the genome over many generations, because organisms with a stronger predisposition to acquire a trait have a selective advantage. Over generations, the amount of environmental exposure required to develop the trait decreases, and eventually no environmental exposure may be needed - the trait is genetically encoded. An example of the Baldwin effect is the development of calluses on the keels and sterna of ostriches. The calluses may initially have developed in response to abrasion where the keel and sterna touch the ground during sitting. Natural selection then favored individuals that could develop calluses more rapidly, until callus development became triggered within the embryo and could occur without environmental stimulation. The PNAS paper explored circumstances under which a similar evolutionary mechanism could genetically assimilate properties of language – a theory that has been widely favoured by those arguing for the existence of 'language genes'.

The study modelled ways in which genes encoding language-specific properties could have coevolved with language itself. The key finding was that genes for language could have coevolved only in a highly stable linguistic environment; a rapidly changing linguistic environment would not provide a stable target for natural selection. Thus, a biological endowment could not coevolve with properties of language that began as learned cultural conventions, because cultural conventions change much more rapidly than genes.

The authors conclude that it is unlikely that humans possess a genetic 'language module' which has evolved by natural selection. The genetic basis of human language appears to primarily predate the emergence of language.

The conclusion is reinforced by the observation that had such adaptation occurred in the human lineage, these processes would have operated independently on modern human populations as they spread throughout Africa and the rest of the world over the last 100,000 years. If this were so, genetic populations should have coevolved with their own language groups, leading to divergent and mutually incompatible language modules. Linguists have found no evidence of this, however; for example, native Australasian populations have been largely isolated for 50,000 years but learn European languages readily.

Professor Nick Chater, UCL Cognitive, Perceptual and Brain Sciences, says: "Language is uniquely human. But does this uniqueness stem from biology or culture? This question is central to our understanding of what it is to be human, and has fundamental implications for the relationship between genes and culture. Our paper uncovers a paradox at the heart of theories about the evolutionary origin and genetic basis of human language – although we have appear to have a genetic predisposition towards language, human language has evolved far more quickly than our genes could keep up with, suggesting that language is shaped and driven by culture rather than biology.

"The linguistic environment is continually changing; indeed, linguistic change is vastly more rapid than genetic change. For example, the entire Indo-European language group has diverged in less than 10,000 years. Our simulations show the evolutionary impact of such rapid linguistic change: genes cannot evolve fast enough to keep up with this 'moving target'.

"Of course, co-evolution between genes and culture can occur. For example, lactose tolerance appears to have co-evolved with dairying. But dairying involves a stable change to the nutritional environment, positively selecting the gene for lactose tolerance, unlike the fast-changing linguistic environment. Our simulations show that this kind of co-evolution can only occur when language change is offset by very strong genetic pressure. Under these conditions of extreme pressure, language rapidly evolves to reflect pre-existing biases, whether the genes are subject to natural selection or not. Thus, co-evolution only occurs when the language is already almost entirely genetically encoded. We conclude that slow-changing genes can drive the structure of a fast-changing language, but not the reverse.

"But if universal grammar did not evolve by natural selection, how could it have arisen? Our findings suggest that language must be a culturally evolved system, not a product of biological adaption. This is consistent with current theories that language arose from the unique human capacity for social intelligence."

Notes for Editors

1. For more information or to set up an interview, please contact Jenny Gimpel in the UCL Media Relations Office on tel: +44 (0)20 7679 9726, mobile: +44 (0)7747 565 056, out of hours +44 (0)7917 271 364, e-mail: j.gimpel@ucl.ac.uk.

3. 'Restrictions on biological adaptation in language evolution' by Nick Chater, Florencia Reali, and Morten Christiansen, is published in the Proceedings of the National Academy of Sciences (PNAS). Journalists can obtain copies of the paper by contacting the UCL Media Relations Office.


http://www.ucl.ac.uk/media/library/humanlanguage


ScienceDaily (Jan. 19, 2009) — Language in humans has evolved culturally rather than genetically, according to a study by UCL (University College London) and US researchers. By modelling the ways in which genes for language might have evolved alongside language itself, the study showed that genetic adaptation to language would be highly unlikely, as cultural conventions change much more rapidly than genes. Thus, the biological machinery upon which human language is built appears to predate the emergence of language.

According to a phenomenon known as the Baldwin effect, characteristics that are learned or developed over a lifespan may become gradually encoded in the genome over many generations, because organisms with a stronger predisposition to acquire a trait have a selective advantage. Over generations, the amount of environmental exposure required to develop the trait decreases, and eventually no environmental exposure may be needed - the trait is genetically encoded.

An example of the Baldwin effect is the development of calluses on the keels and sterna of ostriches. The calluses may initially have developed in response to abrasion where the keel and sterna touch the ground during sitting. Natural selection then favored individuals that could develop calluses more rapidly, until callus development became triggered within the embryo and could occur without environmental stimulation. The PNAS paper explored circumstances under which a similar evolutionary mechanism could genetically assimilate properties of language – a theory that has been widely favoured by those arguing for the existence of 'language genes'.

The study modelled ways in which genes encoding language-specific properties could have coevolved with language itself. The key finding was that genes for language could have coevolved only in a highly stable linguistic environment; a rapidly changing linguistic environment would not provide a stable target for natural selection. Thus, a biological endowment could not coevolve with properties of language that began as learned cultural conventions, because cultural conventions change much more rapidly than genes.

The authors conclude that it is unlikely that humans possess a genetic 'language module' which has evolved by natural selection. The genetic basis of human language appears to primarily predate the emergence of language.

The conclusion is reinforced by the observation that had such adaptation occurred in the human lineage, these processes would have operated independently on modern human populations as they spread throughout Africa and the rest of the world over the last 100,000 years. If this were so, genetic populations should have coevolved with their own language groups, leading to divergent and mutually incompatible language modules. Linguists have found no evidence of this, however; for example, native Australasian populations have been largely isolated for 50,000 years but learn European languages readily.

Professor Nick Chater, UCL Cognitive, Perceptual and Brain Sciences, says: "Language is uniquely human. But does this uniqueness stem from biology or culture? This question is central to our understanding of what it is to be human, and has fundamental implications for the relationship between genes and culture. Our paper uncovers a paradox at the heart of theories about the evolutionary origin and genetic basis of human language – although we have appear to have a genetic predisposition towards language, human language has evolved far more quickly than our genes could keep up with, suggesting that language is shaped and driven by culture rather than biology.

"The linguistic environment is continually changing; indeed, linguistic change is vastly more rapid than genetic change. For example, the entire Indo-European language group has diverged in less than 10,000 years. Our simulations show the evolutionary impact of such rapid linguistic change: genes cannot evolve fast enough to keep up with this 'moving target'.

"Of course, co-evolution between genes and culture can occur. For example, lactose tolerance appears to have co-evolved with dairying. But dairying involves a stable change to the nutritional environment, positively selecting the gene for lactose tolerance, unlike the fast-changing linguistic environment. Our simulations show that this kind of co-evolution can only occur when language change is offset by very strong genetic pressure. Under these conditions of extreme pressure, language rapidly evolves to reflect pre-existing biases, whether the genes are subject to natural selection or not. Thus, co-evolution only occurs when the language is already almost entirely genetically encoded. We conclude that slow-changing genes can drive the structure of a fast-changing language, but not the reverse.

"But if universal grammar did not evolve by natural selection, how could it have arisen? Our findings suggest that language must be a culturally evolved system, not a product of biological adaption. This is consistent with current theories that language arose from the unique human capacity for social intelligence."


Journal reference:

1.                     Nick Chater, Florencia Reali, and Morten Christiansen. Restrictions on biological adaptation in language evolution. Proceedings of the National Academy of Sciences, 19 January 2009

Adapted from materials provided by University College London, via AlphaGalileo.

 

http://www.sciencedaily.com/releases/2009/01/090119210614.htm

Full copy of the article: 'Restrictions on biological adaptation in language evolution' by Nick Chater et al.
www.pnas.org/cgi/doi/10.1073/pnas.0807191106 (National Academy of Sciences of the USA)
Received on 21 Jan. 2009 from:
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www.ucl.ac.uk/media


First Americans arrived as two separate migrations, according to new genetic evidence

http://www.sciencedaily.com/images/2009/01/090108121618-large.jpg

Bering Strait. After the Last Glacial Maximum some 15,000 to 17,000 years ago, one group entered North America from Beringia following the ice-free Pacific coastline, while another traversed an open land corridor between two ice sheets to arrive directly into the region east of the Rocky Mountains. (Beringia is the landmass that connected northeast Siberia to Alaska during the last ice age.) (Credit: NOAA, NPO)

ScienceDaily (Jan. 21, 2009) — The first people to arrive in America traveled as at least two separate groups to arrive in their new home at about the same time, according to new genetic evidence published online in Current Biology.

After the Last Glacial Maximum some 15,000 to 17,000 years ago, one group entered North America from Beringia following the ice-free Pacific coastline, while another traversed an open land corridor between two ice sheets to arrive directly into the region east of the Rocky Mountains. (Beringia is the landmass that connected northeast Siberia to Alaska during the last ice age.) Those first Americans later gave rise to almost all modern Native American groups of North, Central, and South America, with the important exceptions of the Na-Dene and the Eskimos-Aleuts of northern North America, the researchers said.

" Recent data based on archeological evidence and environmental records suggest that humans entered the Americas from Beringia as early as 15,000 years ago, and the dispersal occurred along the deglaciated Pacific coastline," said Antonio Torroni of Università di Pavia, Italy. "Our study now reveals a novel alternative scenario: Two almost concomitant paths of migration, both from Beringia about 15,000 to 17,000 years ago, led to the dispersal of Paleo-Indians—the first Americans."

Such a dual origin for Paleo-Indians has major implications for all disciplines involved in Native American studies, he said. For instance, it implies that there is no compelling reason to presume that a single language family was carried along with the first migrants.

When Columbus reached the Americas in 1492, Native American occupation stretched from the Bering Strait to Tierra del Fuego, Torroni explained. Those native populations encompassed extraordinary linguistic and cultural diversity, which has fueled extensive debate among experts over their interrelationships and origins.

Recently, molecular genetics, together with archaeology and linguistics, has begun to provide some insights. In the new study, Ugo Perego and Alessandro Achilli of Torroni's team analyzed mitochondrial DNA from two rare haplogroups, meaning mitochondrial types that share a common maternal ancestor. Mitochondria are cellular components with their own DNA that allow scientists to trace ancestry and migration because they are passed on directly from mother to child over generations.

Their results show that the haplogroup called D4h3 spread from Beringia into the Americas along the Pacific coastal route, rapidly reaching Tierra del Fuego. The other haplogroup, X2a, spread at about the same time through the ice-free corridor between the Laurentide and Cordilleran Ice Sheets and remained restricted to North America.

" A dual origin for the first Americans is a striking novelty from the genetic point of view and makes plausible a scenario positing that within a rather short period of time, there may have been several entries into the Americas from a dynamically changing Beringian source," the researchers concluded.

The evidence that separate groups of people with distinctive genetic roots entered the Americas independently at the same time strongly implies linguistic and cultural differences between them. "The origin of the first Americans is very controversial to archaeologists and even more so to linguists," said study corresponding author Professor Antonio Torroni, heading the University of Pavia group. "Our genetic study reveals a scenario in which more than one language family could have arrived in the Americas with the earliest Paleo-Indians."

The researchers include Ugo A. Perego, Universita` di Pavia, Pavia, Italy, Sorenson Molecular Genealogy Foundation, Salt Lake City, UT; Alessandro Achilli, Universita` di Pavia, Pavia, Italy, Universita` di Perugia, Perugia, Italy; Norman Angerhofer, Sorenson Molecular Genealogy Foundation, Salt Lake City, UT; Matteo Accetturo, Universita` di Pavia, Pavia, Italy; Maria Pala, Universita` di Pavia, Pavia, Italy; Anna Olivieri, Universita` di Pavia, Pavia, Italy; Baharak Hooshiar Kashani, Universita` di Pavia, Pavia, Italy; Kathleen H. Ritchie, Sorenson Molecular Genealogy Foundation, Salt Lake City, UT; Rosaria Scozzari, Universita` La Sapienza, Rome, Italy; Qing-Peng Kong, Chinese Academy of Sciences, Kunming, Yunnan, China, Yunnan University, Kunming, Yunnan, China; Natalie M. Myres, Sorenson Molecular Genealogy Foundation, Salt Lake City, UT; Antonio Salas, Unidade de Xenetica, Instituto de Medicina Legal, Universidad de Santiago de Compostela, Galicia, Spain; Ornella Semino, Universita` di Pavia, Pavia, Italy; Hans-Jurgen Bandelt, University of Hamburg, Hamburg, Germany; Scott R. Woodward, Sorenson Molecular Genealogy Foundation, Salt Lake City, UT; and Antonio Torroni, Universita` di Pavia, Pavia, Italy.


Journal reference:

1.                     . Distinctive Paleo-Indian Migration Routes from Beringia Marked by Two Rare MtDNA Haplogroups. Current Biology, Online January 8; In Print January 13, 2009

Adapted from materials provided by Cell Press, via EurekAlert!, a service of AAAS.

http://www.sciencedaily.com/releases/2009/01/090108121618.htm


Curr Biol. 2009 Jan 13;19(1):1-8.


Distinctive Paleo-Indian migration routes from Beringia marked by two rare mtDNA haplogroups.

Perego UA, Achilli A, Angerhofer N, Accetturo M, Pala M, Olivieri A, Kashani BH, Ritchie KH, Scozzari R, Kong QP, Myres NM, Salas A, Semino O, Bandelt HJ, Woodward SR, Torroni A.

Dipartimento di Genetica e Microbiologia, Università di Pavia, 27100 Pavia, Italy.

BACKGROUND: It is widely accepted that the ancestors of Native Americans arrived in the New World via Beringia approximately 10 to 30 thousand years ago (kya). However, the arrival time(s), number of expansion events, and migration routes into the Western Hemisphere remain controversial because linguistic, archaeological, and genetic evidence have not yet provided coherent answers. Notably, most of the genetic evidence has been acquired from the analysis of the common pan-American mitochondrial DNA (mtDNA) haplogroups. In this study, we have instead identified and analyzed mtDNAs belonging to two rare Native American haplogroups named D4h3 and X2a. RESULTS: Phylogeographic analyses at the highest level of molecular resolution (69 entire mitochondrial genomes) reveal that two almost concomitant paths of migration from Beringia led to the Paleo-Indian dispersal approximately 15-17 kya. Haplogroup D4h3 spread into the Americas along the Pacific coast, whereas X2a entered through the ice-free corridor between the Laurentide and Cordilleran ice sheets. The examination of an additional 276 entire mtDNA sequences provides similar entry times for all common Native American haplogroups, thus indicating at least a dual origin for Paleo- Indians. CONCLUSIONS: A dual origin for the first Americans is a striking novelty from the genetic point of view, and it makes plausible a scenario positing that within a rather short period of time, there may have been several entries into the Americas from a dynamically changing Beringian source. Moreover, this implies that most probably more than one language family was carried along with the Paleo-Indians.

Publication Types:
PMID: 19135370 [PubMed - in process]

http://www.ncbi.nlm.nih.gov/pubmed/19135370?dopt=Abstract


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