Limits...
Y-chromosomal diversity in the population of Guinea-Bissau: a multiethnic perspective.

Rosa A, Ornelas C, Jobling MA, Brehm A, Villems R - BMC Evol. Biol. (2007)

Bottom Line: Non sub-Saharan influences were associated with the presence of haplogroup R1b-P25 and particular lineages of E3b1-M78.The paternal pool of the Mandenka and Balanta displays evidence of a particularly marked population growth among the Guineans, possibly reflecting the demographic effects of the agriculturalist lifestyle and their putative relationship to the people that introduced early cultivation practices into West Africa.Despite the overall homogeneity in a multiethnic sample, which contrasts with their social structure, minor clusters suggest the imprints of multiple peoples at different timescales: traces of ancestral inhabitants in haplogroups A-M91 and B-M60, today typical of hunter-gatherers; North African influence in E3b1-M78 Y chromosomes, probably due to trans-Saharan contacts; and R1b-P25 lineages reflecting European admixture via the North Atlantic slave trade.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Evolutionary Biology, Estonian Biocentre, Riia 23, Tartu, Estonia. parosa@igc.gulbenkian.pt

ABSTRACT

Background: The geographic and ethnolinguistic differentiation of many African Y-chromosomal lineages provides an opportunity to evaluate human migration episodes and admixture processes, in a pan-continental context. The analysis of the paternal genetic structure of Equatorial West Africans carried out to date leaves their origins and relationships unclear, and raises questions about the existence of major demographic phenomena analogous to the large-scale Bantu expansions. To address this, we have analysed the variation of 31 binary and 11 microsatellite markers on the non-recombining portion of the Y chromosome in Guinea-Bissau samples of diverse ethnic affiliations, some not studied before.

Results: The Guinea-Bissau Y chromosome pool is characterized by low haplogroup diversity (D = 0.470, sd 0.033), with the predominant haplogroup E3a*-M2 shared among the ethnic clusters and reaching a maximum of 82.2% in the Mandenka people. The Felupe-Djola and Papel groups exhibit the highest diversity of lineages and harbor the deep-rooting haplogroups A-M91, E2-M75 and E3*-PN2, typical of Sahel's more central and eastern areas. Their genetic distinction from other groups is statistically significant (P = 0.01) though not attributable to linguistic, geographic or religious criteria. Non sub-Saharan influences were associated with the presence of haplogroup R1b-P25 and particular lineages of E3b1-M78.

Conclusion: The predominance and high diversity of haplogroup E3a*-M2 suggests a demographic expansion in the equatorial western fringe, possibly supported by a local agricultural center. The paternal pool of the Mandenka and Balanta displays evidence of a particularly marked population growth among the Guineans, possibly reflecting the demographic effects of the agriculturalist lifestyle and their putative relationship to the people that introduced early cultivation practices into West Africa. The paternal background of the Felupe-Djola and Papel ethnic groups suggests a better conserved ancestral pool deriving from East Africa, from where they have supposedly migrated in recent times. Despite the overall homogeneity in a multiethnic sample, which contrasts with their social structure, minor clusters suggest the imprints of multiple peoples at different timescales: traces of ancestral inhabitants in haplogroups A-M91 and B-M60, today typical of hunter-gatherers; North African influence in E3b1-M78 Y chromosomes, probably due to trans-Saharan contacts; and R1b-P25 lineages reflecting European admixture via the North Atlantic slave trade.

Show MeSH

Related in: MedlinePlus

Geographic location of Guinea-Bissau and present-day settlement pattern of the ethnic groups considered in this study.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC1976131&req=5

Figure 1: Geographic location of Guinea-Bissau and present-day settlement pattern of the ethnic groups considered in this study.

Mentions: The inhabitants of the Guinea-Bissau area have certainly been under the influence of several demographic events since prehistorical times, as a result of migratory movements, trade networks and consecutive invasions. The first recorded influx of ethnically defined groups is the arrival of Fulbe people in the 8th century AD, from a Central African epicenter [21]. First contact with the North African Berbers dates back to at least the 9th century, and was repeated in the 11th century when, pushed by the Omníades, these people came to occupy the vicinity of Senegal [22]. The economic shift in the Sahel allowed more centralized states to form (namely the "Black Kingdoms" in the period between the 8th and 16th centuries, [23]), linked by a trading corridor reaching from Mauritania to Niger [18]. In the following centuries pastoral Fulbe arrived again slowly but en masse, together with the Mandenka, and became the most prevalent people in Guinea-Bissau territory. Oral tradition also states that the Djola people – Felupe-Djola, Baiote and possibly Beafada – came from Sudan in the 15th-16th centuries [24]. As for the Balanta, Sudanese or Bantu affinities may argue for their cultural and phenotypic aspects. Though research on the background of the Nalú is less advanced, Teixeira da Mota [25] considers them to be the autochthonous people of the region. The same author identifies Bijagós as a separated branch of Djola or relatives of Papel and Nalú. The main ethnic groups now present in Guinea-Bissau (Figure 1; see Additional file 1) were already settled in the region in the 15th century, at the time of arrival of the Portuguese. With the establishment of the Atlantic slave trade the region experienced an input of Europeans, in their vast majority males, whose genetic imprint is undetermined. Many of the ethnic barriers were brought down, in particular the endogamic practices, promoting an intense cultural contact and higher levels of admixture between groups than before.


Y-chromosomal diversity in the population of Guinea-Bissau: a multiethnic perspective.

Rosa A, Ornelas C, Jobling MA, Brehm A, Villems R - BMC Evol. Biol. (2007)

Geographic location of Guinea-Bissau and present-day settlement pattern of the ethnic groups considered in this study.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC1976131&req=5

Figure 1: Geographic location of Guinea-Bissau and present-day settlement pattern of the ethnic groups considered in this study.
Mentions: The inhabitants of the Guinea-Bissau area have certainly been under the influence of several demographic events since prehistorical times, as a result of migratory movements, trade networks and consecutive invasions. The first recorded influx of ethnically defined groups is the arrival of Fulbe people in the 8th century AD, from a Central African epicenter [21]. First contact with the North African Berbers dates back to at least the 9th century, and was repeated in the 11th century when, pushed by the Omníades, these people came to occupy the vicinity of Senegal [22]. The economic shift in the Sahel allowed more centralized states to form (namely the "Black Kingdoms" in the period between the 8th and 16th centuries, [23]), linked by a trading corridor reaching from Mauritania to Niger [18]. In the following centuries pastoral Fulbe arrived again slowly but en masse, together with the Mandenka, and became the most prevalent people in Guinea-Bissau territory. Oral tradition also states that the Djola people – Felupe-Djola, Baiote and possibly Beafada – came from Sudan in the 15th-16th centuries [24]. As for the Balanta, Sudanese or Bantu affinities may argue for their cultural and phenotypic aspects. Though research on the background of the Nalú is less advanced, Teixeira da Mota [25] considers them to be the autochthonous people of the region. The same author identifies Bijagós as a separated branch of Djola or relatives of Papel and Nalú. The main ethnic groups now present in Guinea-Bissau (Figure 1; see Additional file 1) were already settled in the region in the 15th century, at the time of arrival of the Portuguese. With the establishment of the Atlantic slave trade the region experienced an input of Europeans, in their vast majority males, whose genetic imprint is undetermined. Many of the ethnic barriers were brought down, in particular the endogamic practices, promoting an intense cultural contact and higher levels of admixture between groups than before.

Bottom Line: Non sub-Saharan influences were associated with the presence of haplogroup R1b-P25 and particular lineages of E3b1-M78.The paternal pool of the Mandenka and Balanta displays evidence of a particularly marked population growth among the Guineans, possibly reflecting the demographic effects of the agriculturalist lifestyle and their putative relationship to the people that introduced early cultivation practices into West Africa.Despite the overall homogeneity in a multiethnic sample, which contrasts with their social structure, minor clusters suggest the imprints of multiple peoples at different timescales: traces of ancestral inhabitants in haplogroups A-M91 and B-M60, today typical of hunter-gatherers; North African influence in E3b1-M78 Y chromosomes, probably due to trans-Saharan contacts; and R1b-P25 lineages reflecting European admixture via the North Atlantic slave trade.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Evolutionary Biology, Estonian Biocentre, Riia 23, Tartu, Estonia. parosa@igc.gulbenkian.pt

ABSTRACT

Background: The geographic and ethnolinguistic differentiation of many African Y-chromosomal lineages provides an opportunity to evaluate human migration episodes and admixture processes, in a pan-continental context. The analysis of the paternal genetic structure of Equatorial West Africans carried out to date leaves their origins and relationships unclear, and raises questions about the existence of major demographic phenomena analogous to the large-scale Bantu expansions. To address this, we have analysed the variation of 31 binary and 11 microsatellite markers on the non-recombining portion of the Y chromosome in Guinea-Bissau samples of diverse ethnic affiliations, some not studied before.

Results: The Guinea-Bissau Y chromosome pool is characterized by low haplogroup diversity (D = 0.470, sd 0.033), with the predominant haplogroup E3a*-M2 shared among the ethnic clusters and reaching a maximum of 82.2% in the Mandenka people. The Felupe-Djola and Papel groups exhibit the highest diversity of lineages and harbor the deep-rooting haplogroups A-M91, E2-M75 and E3*-PN2, typical of Sahel's more central and eastern areas. Their genetic distinction from other groups is statistically significant (P = 0.01) though not attributable to linguistic, geographic or religious criteria. Non sub-Saharan influences were associated with the presence of haplogroup R1b-P25 and particular lineages of E3b1-M78.

Conclusion: The predominance and high diversity of haplogroup E3a*-M2 suggests a demographic expansion in the equatorial western fringe, possibly supported by a local agricultural center. The paternal pool of the Mandenka and Balanta displays evidence of a particularly marked population growth among the Guineans, possibly reflecting the demographic effects of the agriculturalist lifestyle and their putative relationship to the people that introduced early cultivation practices into West Africa. The paternal background of the Felupe-Djola and Papel ethnic groups suggests a better conserved ancestral pool deriving from East Africa, from where they have supposedly migrated in recent times. Despite the overall homogeneity in a multiethnic sample, which contrasts with their social structure, minor clusters suggest the imprints of multiple peoples at different timescales: traces of ancestral inhabitants in haplogroups A-M91 and B-M60, today typical of hunter-gatherers; North African influence in E3b1-M78 Y chromosomes, probably due to trans-Saharan contacts; and R1b-P25 lineages reflecting European admixture via the North Atlantic slave trade.

Show MeSH
Related in: MedlinePlus