Mestizos in Mexico
Total population | |
---|---|
est. 60–107 million (50–90% of population) Varies depending on the criteria used | |
Languages | |
Mexican Spanish and minority languages | |
Religion | |
Roman Catholicism, Protestantism | |
Related ethnic groups | |
Indigenous Mexicans, White Mexicans, Afro-Mexicans, Asian Mexicans, Arab Mexicans |
Mexican Mestizos are an ethnic group in Mexico which can be defined either by cultural criteria (the language spoken) or a more strict biological criteria. Because of this, estimates of the number of Mestizos in Mexico can vary.[1][2][3][4][5]
The application of the term Mestizo (lit. mixed) has changed over time. The word was originally used in the colonial era to refer to individuals who were of half-Spanish and half-indigenous American ancestry. It was one of the many extant castes used to classify individuals. Once Mexico achieved its independence, the casta system was abandoned and mestizo was used to refer to all the people who were mixed race. After the Mexican Revolution, the term became cultural and was used to refer to the segment of the Mexican population who did not speak indigenous languages. The term mestizo thus became a cultural identity that grouped racially mixed people (including African and Asian ancestry) and unmixed individuals with a mestizo culture. This change of definition was the product of an ideology known as “mestizaje” which was promoted by the early post-Revolution government, seeking to create a unified Mexican identity with no racial distinctions.[1] The advent of DNA sequencing since then has allowed for the study of Mexico's mestizo population.
Today, people of various different phenotypes make up the Mestizo population in Mexico. However, since the term carries a variety of socio-cultural, economic, racial, and genetic meanings, estimates of the Mexican Mestizo population vary widely. According to the Encyclopædia Britannica, which uses a biology-based approach, between one half and two thirds of the Mexican population is Mestizo.[6] A culture-based estimate gives the percentage of Mestizos as high as 90%.[1] Paradoxically, the word Mestizo has long been dropped from popular Mexican vocabulary, with the word even having pejorative connotations,[7] which further complicates attempts to quantify Mestizos via self-identification.
History
Miscegenation and culture-mixing have been occurring in Mexico for nearly five centuries, and has resulted in a unique Mestizo, and more broadly, Mexican identity. Mexicans who are biologically Mestizos are primarily of European and Native American ancestry. The third largest component are sub-Saharan African, a legacy of the slavery in New Spain (which saw the importation of some 100,000[8]-200,000[9] black slaves). However, geneticists theorize that in regions of Mexico that did not have any presence of slaves, traces of African ancestry might have come from Spanish colonists and not African slaves themselves, as said ancestry is of North African and Near East origin.[10] Depending on the region, some may have small traces of Asian admixture due the thousands of Filipinos and Chinos (Asian slaves of diverse origin, not just Chinese) that arrived on the Nao de China. More recent Asian immigration (specifically Chinese) may help explain the comparatively high Asian contribution in Northwest Mexico (i.e., Sonora). The INMEGEN report also notes that on average, the largest genetic component of the self-identified Mestizo Mexicans is indigenous, while African and Asian genetic markers are diminishing with each generation and will continue to do so without new migration.[9] For example, there was an estimated 600,000 Afromestizos (Mestizos of significant African descent) at the end of the colonial period (10% of the population),[11] while as of 2015, the number of self identified Afro-Mexicans was 1.38 million (1.2% of the population).[12]
The large majority of Mexicans can be classified as "Mestizos", meaning in modern Mexican usage that they do not speak indigenous languages. By the deliberate efforts of post-revolutionary governments the "Mestizo identity" was constructed as the base of the modern Mexican national identity, through a process of cultural synthesis referred to as mestizaje ([mes.tiˈsa.xe]). Mexican politicians and reformers such as José Vasconcelos and Manuel Gamio were instrumental in building a Mexican national identity on the concept of mestizaje (the process of race mixture).[13][14]
Cultural policies in early post-revolutionary Mexico were paternalistic towards the indigenous people, with efforts designed to "help" indigenous peoples achieve the same level of progress as the Mestizo society, eventually assimilating indigenous peoples completely to mainstream Mexican culture, working toward the goal of eventually solving the "Indian problem" by transforming indigenous communities into Mestizo communities.[15]
The term "Mestizo" is not in wide use in Mexican society today and has been dropped as a category in population censuses; it is, however, still used in social and cultural studies when referring to the non-indigenous part of the Mexican population. The word has somewhat pejorative connotations and most of the Mexican citizens who would be defined as mestizos in the sociological literature would probably self-identify primarily as Mexicans. In the Yucatán peninsula the word mestizo is even used about Maya-speaking populations living in traditional communities, because during the caste war of the late 19th century those Maya who did not join the rebellion were classified as mestizos.[7] In Chiapas, the term Ladino is used instead of mestizo.[16]
Sometimes, particularly outside of Mexico, the word "mestizo" is used with the meaning of Mexican persons with mixed Indigenous and European blood. This usage does not conform to the Mexican social reality where a person of pure indigenous genetic heritage would be considered mestizo either by rejecting his indigenous culture or by not speaking an indigenous language,[7] and a person with a very low or without any percentage of indigenous genetic heritage would be considered fully indigenous either by speaking an indigenous language or by identifying with a particular indigenous cultural heritage.[2]
While for most of its history the concept of Mestizo and Mestizaje has been lauded by Mexico’s intellectual circles, in recent times the concept has been target of criticism, with it's detractors claiming that it delegitimizes racist practices in Mexico under the idea of “(Racism) Not existing here (Mexico), as everybody is Mestizo” the Mestizo ideology thus, has cemented a terrain of resistance in regards to social, politic and academic mobility around the theme of race in Mexico.[17] In general, the authors conclude that Mexico introducing a real racial classification and accepting itself as a multicultural country opposed to a monolithic Mestizo country would bring benefits to the Mexican society as a whole.[18]
Genetic studies
Population genetics
Autosomal studies
Genetic research in the Mexican population is numerous and has yielded a myriad of different results, it is not rare that different genetic studies done in the same location vary greatly, clear examples of said variation are the city of Monterrey in the state of Nuevo León, which, depending of the study presents an average European ancestry ranging from 38%[20] to 78%,[21] and Mexico City, whose European admixture ranges from as little as 21%[22]
to 70%,[23] reasons behind such variation may include the socioeconomic background of the analyzed samples[23] as well as the criteria to recruit volunteers: some studies only analyze Mexicans who self-identify as Mestizos,[24] others may classify the entire Mexican population as "mestizo",[25] other studies may do both, such as the 2009 genetic study published by the INMEGEN (Mexico's National Institute of Genomic Medicine), which states that 93% of the Mexican population is Mestizo with the remaining being Amerindian, however for it's study the institute only recruited people who explicitly self-identified as mestizos.[9] Finally there are studies who avoid using any racial classification whatsoever, including in them any person that self-identifies as Mexican, this studies are the ones who usually report the highest European admixture for a given location.[26]
Regardless of the criteria used all the autosomal DNA studies made coincide on there being a significant genetic variation depending of the region analyzed, with southern Mexico having prevalent Amerindian and small but higher than average African genetic contributions, the central region of Mexico shows a balance between Amerindian and European components,[27] with the later gradually increasing as one travels northwards and westwards, where European ancestry becomes the majority of the genetic contribution[28] up until cities located in the Mexico-United States border, where studies suggest there is a significant resurgence of Amerindian and African admixture.[29]
A 2006 study conducted by Mexico's National Institute of Genomic Medicine (INMEGEN), which genotyped 104 samples, reported that mestizo Mexicans are 58.96% European, 35.05% "Asian" (primarily Amerindian), and 5.03% Other.[30]
Research conducted by the country's Instituto Nacional de Medicina Genómica (INMEGEN) has found that Mexico's Mestizo population is not uniform in its genetic composition, with there being significant regional variation.[9] For example, mestizos of primarily European ancestry predominate in Sonora, while mestizos from the central region (Guanajuato and Zacatecas) have a more even split between indigenous and European.[9] The highest African contribution in the twelve participating states (picked to be representative of the major regions of Mexico) was found in Guerrero and Veracruz, while the highest Asian contribution was found in Guerrero and Sonora.[9]
An study made by the University College London which included multiple Latin American countries and was made with collaboration of each countries' antrophology and genetics institutes reported the genetic ancestry of Mexican Mestizos was 56% Native American, 37% European and 5% African making Mexico, after Peru, the country with the highest Amerindian ancestry. Additionally, different phenotypical traits were analyzed, with the study determining that that the frequency of blond hair and light eyes in Mexicans was of 18.5% and 28.5% respectively,[31] making Mexico also the country with the second highest frequency of blond hair in the study, the reason behind such discrepancy between phenotypical trais and genetic ancestry may lie in the fact that the samples used in Mexico's case were highly unproportional, as the northern and western regions of Mexico contain 45% of Mexico's population, but no more than 10% of the samples used in the study came from the states located in these regions. For the most part, the rest of the samples hailed from Mexico City and southern Mexican states.[32]
Additional studies suggests a tendency relating a higher European admixture with a higher socioeconomic status and a higher Amerindian ancestry with a lower socioeconomic status: a study made exclusively on low income Mestizos residing in Mexico City found the mean admixture to be 0.590, 0.348, and 0.062 for Amerindian, European and African respectively whereas the European admixture increased to an average of around 70% on mestizos belonging to a higher socioeconomical level.[33] In 2011, an autosomal dna study was conducted in Mexico city, with 1,310 samples, showing the average proportion of Native American, European, and African ancestry for the population to be 64%, 32%, and 4% respectively. Additional autosomal dna studies conducted on people from Mexico city show a predominate Native American background, with Native American ancestry ranging from 61-69% in 5 different studies. The number of people sampled in these studies ranged from 66 to 984 people.[34][35][36][37][38] One outlier study showed a predominate European background for mestizos of Mexico City, showing 57% European ancestry, 40% Native American ancestry, and 3% African ancestry. The sample population for this study however, was only 19 people.[19]
MtDna and Y DNA studies
A 2012 study published by the Journal of Human Genetics Y chromosomes found the deep paternal ancestry of the Mexican mestizo population to be predominately European (64.9%), followed by Amerindian (30.8%) and Asian (1.2%).[39] The European Y chromosome was more prevalent in the north and west (66.7-95%) and Native American ancestry increased in the center and southeast (37-50%), the African ancestry was low and relatively homogeneous (0-8.8%).[39] The states that participated in this study where Aguascalientes, Chiapas, Chihuahua, Durango, Guerrero, Jalisco, Oaxaca, Sinaloa, Veracruz and Yucatán.[40] The largest amount of chromosomes found were identified as belonging to the haplogroups from Western Europe, East Europe and Eurasia, Siberia and the Americas and Northern Europe with relatively smaller traces of haplogroups from Central Asia, South-east Asia, South-central Asia, Western Asia, The Caucasus, North Africa, Near East, East Asia, North-east Asia, South-west Asia and the Middle East.[41] Also a study published in 2011 on Mexican Mitochondrial DNA found that maternal ancestry was predominately Native American (85-90%), with a minority having European (5-7%) or African (3-5%) mtDNA.[42]
An autosomal ancestry study performed on Mexico city reported that the European ancestry of Mexicans was 52% with the rest being Amerindian and a small African contribution, additionally maternal ancestry was analyzed, with 47% being of European origin. The only criteria for sample selection was that the volunteers self-identified as Mexicans.[26]
See also
References and footnotes
- 1 2 3 en el censo de 1930 el gobierno mexicano dejó de clasificar a la población del país en tres categorías raciales, blanco, mestizo e indígena, y adoptó una nueva clasificación étnica que distinguía a los hablantes de lenguas indígenas del resto de la población, es decir de los hablantes de español. Archived 2013-08-23 at the Wayback Machine.
- 1 2 Knight, Alan (1990). "Racism, Revolution and indigenismo: Mexico 1910–1940". In Graham, Richard. The Idea of Race in Latin America, 1870–1940. Austin: University of Texas Press. pp. 71–113 [p. 73]. ISBN 0-292-73856-0.
- ↑ Bartolomé, Miguel Alberto (1996). "Pluralismo cultural y redefinicion del estado en México" (PDF). Coloquio sobre derechos indígenas. Oaxaca: IOC. p. 5. ISBN 968-6951-31-8.
- ↑ "El impacto del mestizaje en México", “Investigación y Ciencia”, Spain, October 2013. Retrieved on 01 June 2017.
- ↑ "Al respecto no debe olvidarse que en estos países buena parte de las personas consideradas biológicamente blancas son mestizas en el aspecto cultural, el que aquí nos interesa (p. 196)" (PDF). Redalyc.org. 2005-03-16. Archived from the original (PDF) on 2013-10-22. Retrieved 2013-06-27.
- ↑ "Mexico- Ethnic groups". Encyclopædia Britannica. Retrieved 1 October 2016.
- 1 2 3 Bartolomé, Miguel Alberto (1996). "Pluralismo cultural y redefinicion del estado en México" (PDF). Coloquio sobre derechos indígenas. Oaxaca: IOC. p. 2. ISBN 968-6951-31-8.
- ↑ Rayna Bailey (2010). Immigration and Migration. Infobase Publishing. p. 93. ISBN 9780816071067. Retrieved June 1, 2017.
- 1 2 3 4 5 6 Analysis of genomic diversity in Mexican Mestizo populations to develop genomic medicine in Mexico Silva-Zolezzi I, Hidalgo-Miranda A, Estrada-Gil J, Fernandez-Lopez JC, Uribe-Figueroa L, Contreras A, Balam-Ortiz E, del Bosque-Plata L, Velazquez Fernandez D, Lara C, Goya R, Hernandez-Lemus E, Davila C, Barrientos E, March S, Jimenez-Sanchez G. | National Institute of Genomic Medicine| May 26, 2009 "
- ↑ "Genoma destapa diferencias de mexicanos".
- ↑ "Chapter 2". Historia de Mexico, Legado Historico Y Pasado Reciente. Table 2.1: Pearson Educación. 2004. ISBN 9789702605232. Retrieved October 1, 2016.
- ↑ "Principales resultados de la Encuesta Intercensal 2015 Estados Unidos Mexicanos" (PDF). INEGI. p. 77. Archived from the original (PDF) on 10 December 2015. Retrieved 9 December 2015.
- ↑ Wade, Peter (1997). Race and Ethnicity in Latin America. Chicago: Pluto Press. p. 32. ISBN 0-7453-0987-9.
- ↑ Knight, Alan (1990). "Racism, Revolution and indigenismo: Mexico 1910–1940". In Graham, Richard. The Idea of Race in Latin America, 1870–1940. Austin: University of Texas Press. pp. 71–113 [pp. 78–85]. ISBN 0-292-73856-0.
- ↑ Bartolomé, Miguel Alberto (1996). "Pluralismo cultural y redefinicion del estado en México" (PDF). Coloquio sobre derechos indígenas. Oaxaca: IOC. p. 5. ISBN 968-6951-31-8.
- ↑ Wade, Peter (1997). Race and Ethnicity in Latin America. Chicago: Pluto Press. pp. 44–47. ISBN 0-7453-0987-9.
- ↑ "El archivo del estudio de racismo en Mexico".
- ↑ "El mestizaje en Mexico" (PDF).
- 1 2 Wang, Sijia; Ray, Nicolas; Rojas, Winston; Parra, Maria V.; Bedoya, Gabriel; Gallo, Carla; Poletti, Giovanni; Mazzotti, Guido; Hill, Kim; Hurtado, Ana M.; Camrena, Beatriz; Nicolini, Humberto; Klitz, William; Barrantes, Ramiro; Molina, Julio A.; Freimer, Nelson B.; Bortolini, Maria Cátira; Salzano, Francisco M.; Petzl-Erler, Maria L.; Tsuneto, Luiza T.; Dipierri, José E.; Alfaro, Emma L.; Bailliet, Graciela; Bianchi, Nestor O.; Llop, Elena; Rothhammer, Francisco; Excoffier, Laurent; Ruiz-Linares, Andrés (2008). "Geographic Patterns of Genome Admixture in Latin American Mestizos". PLoS Genetics. 4 (3): e1000037. PMC 2265669 . PMID 18369456. doi:10.1371/journal.pgen.1000037.
- ↑ "Ancestry informative markers and admixture proportions in northeastern Mexico", Pubmed, Retrieved on 15 May 2017.
- ↑ "Genetic structure of the populations migrating from San Luis Potosi and Zacatecas to Nuevo León in Mexico.". Hum Biol. 63: 309–27. June 1991. PMID 2055589.
- ↑ "Population Data of Nine STRs of Mexican-Mestizos From Mexico City", Pubmed, Retrieved on 15 May 2017.
- 1 2 "Racial admixture in a Mestizo population from Mexico City". American Journal of Human Biology. 7: 213–216. 27 May 2005. doi:10.1002/ajhb.1310070210. Retrieved 9 September 2013.
- ↑ J.K. Estrada; A. Hidalgo-Miranda; I. Silva-Zolezzi; G. Jimenez-Sanchez. "Evaluation of Ancestry and Linkage Disequilibrium Sharing in Admixed Population in Mexico". ASHG. Retrieved 18 July 2012.
- ↑ Martínez-Cortés, G; Salazar-Flores, J; Fernández-Rodríguez, LG; Rubi-Castellanos, R; Rodríguez-Loya, C; Velarde-Félix, JS; Muñoz-Valle, JF; Parra-Rojas, I; Rangel-Villalobos, H (2012). "Admixture and population structure in Mexican-Mestizos based on paternal lineages -". J. Hum. Genet. Journal of Human Genetics. 57: 568–74. PMID 22832385. doi:10.1038/jhg.2012.67.
In the total population sample, paternal ancestry was predominately European (64.9%), followed by Native American (30.8%) and African (4.2%).
- 1 2 "A Genomewide Admixture Map for Latino Populations", Pubmed, Retrieved on 15 May 2017.
- ↑ "STR for 15 Loci in a population Sample From the Central Region of Mexico", Pubmed, Retrieved on 15 May 2017.
- ↑ "Genetic admixture in three Mexican Mestizo populations based on D1S80 and HLA-DQA1 loci.". Am J Hum Biol. 14 (2): 257–63. PMID 11891937. doi:10.1002/ajhb.10020.
- ↑ "SNP-19 genotypic variants of CAPN10 gene and its relation to diabetes mellitus type 2 in a population of Ciudad Juarez, Mexico", Pubmed, Retrieved on 15 May 2017.
- ↑ J.K. Estrada; A. Hidalgo-Miranda; I. Silva-Zolezzi; G. Jimenez-Sanchez. "Evaluation of Ancestry and Linkage Disequilibrium Sharing in Admixed Population in Mexico". ASHG. Retrieved July 18, 2012.
- ↑ "Admixture in Latin America: Geographic Structure, Phenotypic Diversity and Self-Perception of Ancestry Based on 7,342 Individuals" table 1, Plosgenetics, 25 September 2014. Retrieved on 9 May 2017.
- ↑ Ruiz-Linares, Andrés; Adhikari, Kaustubh; Acuña-Alonzo, Victor; Quinto-Sanchez, Mirsha; Jaramillo, Claudia; Arias, William; Fuentes, Macarena; Pizarro, María; Everardo, Paola; De Avila, Francisco; Gómez-Valdés, Jorge; León-Mimila, Paola; Hunemeier, Tábita; Ramallo, Virginia; Silva De Cerqueira, Caio C.; Burley, Mari-Wyn; Konca, Esra; De Oliveira, Marcelo Zagonel; Veronez, Mauricio Roberto; Rubio-Codina, Marta; Attanasio, Orazio; Gibbon, Sahra; Ray, Nicolas; Gallo, Carla; Poletti, Giovanni; Rosique, Javier; Schuler-Faccini, Lavinia; Salzano, Francisco M.; Bortolini, Maria-Cátira; et al. (2014). "Admixture in Latin America: Geographic Structure, Phenotypic Diversity and Self-Perception of Ancestry Based on 7,342 Individuals". PLoS Genetics. 10 (9): e1004572. PMC 4177621 . PMID 25254375. doi:10.1371/journal.pgen.1004572.
- ↑ Lisker, Rubén; Ramírez, Eva; González-Villalpando, Clicerio; Stern, Michael P. (1995). "Racial admixture in a Mestizo population from Mexico City". American Journal of Human Biology. 7 (2): 213–6. doi:10.1002/ajhb.1310070210.
- ↑ Martinez-Marignac, Veronica L.; Valladares, Adan; Cameron, Emily; Chan, Andrea; Perera, Arjuna; Globus-Goldberg, Rachel; Wacher, Niels; Kumate, Jesús; McKeigue, Paul; o'Donnell, David; Shriver, Mark D.; Cruz, Miguel; Parra, Esteban J. (2006). "Admixture in Mexico City: Implications for admixture mapping of Type 2 diabetes genetic risk factors". Human Genetics. 120 (6): 807–19. PMID 17066296. doi:10.1007/s00439-006-0273-3.
- ↑ Juárez-Cedillo, Teresa; Zuñiga, Joaquín; Acuña-Alonzo, Victor; Pérez-Hernández, Nonanzit; Rodríguez-Pérez, José Manuel; Barquera, Rodrigo; Gallardo, Guillermo J.; Sánchez-Arenas, Rosalinda; García-Peña, Maria del Carmen; Granados, Julio; Vargas-Alarcón, Gilberto (2008). "Genetic admixture and diversity estimations in the Mexican Mestizo population from Mexico City using 15 STR polymorphic markers". Forensic Science International: Genetics. 2 (3): e37–9. PMID 19083813. doi:10.1016/j.fsigen.2007.08.017.
- ↑ Kosoy, Roman; Nassir, Rami; Tian, Chao; White, Phoebe A.; Butler, Lesley M.; Silva, Gabriel; Kittles, Rick; Alarcon-Riquelme, Marta E.; Gregersen, Peter K.; Belmont, John W.; de la Vega, Francisco M.; Seldin, Michael F. (2009). "Ancestry informative marker sets for determining continental origin and admixture proportions in common populations in America". Human Mutation. 30 (1): 69–78. PMC 3073397 . PMID 18683858. doi:10.1002/humu.20822.
- ↑ Rubi-Castellanos, Rodrigo; Martínez-Cortés, Gabriela; Francisco Muñoz-Valle, José; González-Martín, Antonio; Cerda-Flores, Ricardo M.; Anaya-Palafox, Manuel; Rangel-Villalobos, Héctor (2009). "Pre-Hispanic Mesoamerican demography approximates the present-day ancestry of Mestizos throughout the territory of Mexico". American Journal of Physical Anthropology. 139 (3): 284–94. PMID 19140185. doi:10.1002/ajpa.20980.
- ↑ Johnson, Nicholas A.; Coram, Marc A.; Shriver, Mark D.; Romieu, Isabelle; Barsh, Gregory S.; London, Stephanie J.; Tang, Hua (2011). "Ancestral Components of Admixed Genomes in a Mexican Cohort". PLoS Genetics. 7 (12): e1002410. PMC 3240599 . PMID 22194699. doi:10.1371/journal.pgen.1002410.
- 1 2 Martínez-Cortés, Gabriela; Salazar-Flores, Joel; Gabriela Fernández-Rodríguez, Laura; Rubi-Castellanos, Rodrigo; Rodríguez-Loya, Carmen; Velarde-Félix, Jesús Salvador; Franciso Muñoz-Valle, José; Parra-Rojas, Isela; Rangel-Villalobos, Héctor (2012). "Admixture and population structure in Mexican-Mestizos based on paternal lineages". Journal of Human Genetics. 57 (9): 568–74. PMID 22832385. doi:10.1038/jhg.2012.67.
- ↑ Figure 3 from Martínez-Cortés, Gabriela; Salazar-Flores, Joel; Gabriela Fernández-Rodríguez, Laura; Rubi-Castellanos, Rodrigo; Rodríguez-Loya, Carmen; Velarde-Félix, Jesús Salvador; Franciso Muñoz-Valle, José; Parra-Rojas, Isela; Rangel-Villalobos, Héctor (2012). "Admixture and population structure in Mexican-Mestizos based on paternal lineages". Journal of Human Genetics. 57 (9): 568–74. PMID 22832385. doi:10.1038/jhg.2012.67.
- ↑ Figure 2 from Martínez-Cortés, Gabriela; Salazar-Flores, Joel; Gabriela Fernández-Rodríguez, Laura; Rubi-Castellanos, Rodrigo; Rodríguez-Loya, Carmen; Velarde-Félix, Jesús Salvador; Franciso Muñoz-Valle, José; Parra-Rojas, Isela; Rangel-Villalobos, Héctor (2012). "Admixture and population structure in Mexican-Mestizos based on paternal lineages". Journal of Human Genetics. 57 (9): 568–74. PMID 22832385. doi:10.1038/jhg.2012.67.
- ↑ Kumar, Satish; Bellis, Claire; Zlojutro, Mark; Melton, Phillip E; Blangero, John; Curran, Joanne E (2011). "Large scale mitochondrial sequencing in Mexican Americans suggests a reappraisal of Native American origins". BMC Evolutionary Biology. 11: 293. PMC 3217880 . PMID 21978175. doi:10.1186/1471-2148-11-293.