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Post by Admin on Jun 10, 2021 2:54:03 GMT
Admixture analyses The results of the exact test of population differentiation performed on the haplogroup profile distributions confirm the discrete nature of each African coast (results not shown). In order to estimate the proportion of maternal ancestry from each major slaving coast present in the population of modern Jamaican mtDNA, admixture models using both haplogroup profiles and haplotype similarities from the African coasts were fitted to the pool of sampled Jamaicans. Combinations excluding marginal populations were also explored to investigate any contribution these groups may have on the regional haplogroup profile distribution. These estimated admixture coefficients are summarized in Tables 2 and 3, respectively.
Table 2 Admixture coefficients ± SD for parental populations calculated using haplogroup profile distributions
All Jamaica (n = 390) Senegambia (n = 892) 0.049 ± 0.040 Sierra Leone (n = 823) 0.096 ± 0.07 Gold Coast (n = 505) 0.477 ± 0.12 Bight of Benin (n = 421) 0.123 ± 0.10 Bight of Biafra (n = 3641) 0.064 ± 0.05 West-central Africa (n = 1403) 0.089 ± 0.05 Southeast Africa (n = 775) 0.092 ± 0.03 East Africa (n = 805) 0.010 ± 0.01 w/o Sahelian Jamaica (n = 390) Senegambia (n = 39) 0.075 ± 0.05 Sierra Leone (n = 659) 0.092 ± 0.07 Gold Coast (n = 491) 0.336 ± 0.15 Bight of Benin (n = 297) 0.261 ± 0.15 Bight of Biafra (n = 3008) 0.060 ± 0.05 West-central Africa (n = 1403) 0.081 ± 0.05 Southeast Africa (n = 775) 0.088 ± 0.03 East Africa (n = 805) 0.009 ± 0.01 w/o Pygmies Jamaica (n = 390) Senegambia (n = 892) 0.048 ± 0.04 Sierra Leone (n = 823) 0.092 ± 0.07 Gold Coast (n = 505) 0.456 ± 0.11 Bight of Benin (n = 421) 0.105 ± 0.09 Bight of Biafra (n = 3097) 0.095 ± 0.08 West-central Africa (n = 1314) 0.109 ± 0.06 Southeast Africa (n = 775) 0.085 ± 0.03 East Africa (n = 753) 0.009 ± 0.009 w/o Sahelian or Pygmies Jamaica (n = 390) Senegambia (n = 39) 0.072 ± 0.04 Sierra Leone (n = 659) 0.092 ± 0.07 Gold Coast (n = 491) 0.343 ± 0.14 Bight of Benin (n = 297) 0.214 ± 0.14 Bight of Biafra (n = 2464) 0.091 ± 0.07 West-central Africa (n = 1314) 0.097 ± 0.06 Southeast Africa (n = 775) 0.083 ± 0.03 East Africa (n = 753) 0.008 ± 0.01
Varying parts of the western coast of Africa contributed to the British trans-Atlantic slave trade in differing intensities over differing periods; however, the Gold Coast embarked slaves for the New World in consistently great numbers between the beginning of the 18th century and the 1790 s.
Using haplogroup distributions to calculate parental population contribution, the largest admixture coefficient was associated with the Gold Coast (0.477 ± 0.12), suggesting that the people from this region may have been consistently prolific throughout the slave era on Jamaica. The diminutive admixture coefficients associated with the Bight of Biafra and West-central Africa (0.064 ± 0.05 and 0.089 ± 0.05, respectively) is striking considering the massive influx of individuals from these areas in the waning years of the British Slave trade. When excluding the pygmy groups, the contribution from the Bight of Biafra and West-central rise to their highest levels (0.095 ± 0.08 and 0.109 ± 0.06, respectively), though still far from a major contribution. When admixture coefficients were calculated by assessing shared haplotypes, the Gold Coast also had the largest contribution, though much less striking at 0.196, with a 95% confidence interval of 0.189 to 0.203. Interestingly, when haplotypes are allowed to differ by one base pair, the Jamaican matriline shows the greatest affinity with the Bight of Benin, though both Bight of Biafra and West-central Africa remain underrepresented.
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Post by Admin on Jun 10, 2021 5:32:34 GMT
Diversity and demographic analyses The results of the evaluation on genetic diversity and demography of the parental populations and of the Jamaican mitochondrial gene pool are summarized in Table 4. All parental groups show expectedly high levels of diversity with regards to θπ, as well as signs of expansion with regards to the unimodal stepwise expansion indices RI and SSD. All groups produced negative values for Tajima's D, also indicating population expansion and departure from the mutation drift equilibrium, although West-central and Southeast Africa failed to produce significant p-values. Sampled Jamaicans fall within the range for diversity and demographic indices, providing no evidence of founder effect.
Table 4 Genetic diversity and demographic statistics for the Jamaicans of African maternal decent and comparative population samples From: Interdisciplinary approach to the demography of Jamaica
Sample n k S θπ ± SD D RI SSD Jamaica 390 231 95 7.28 ± 3.42 -1.46* 0.0044 0.0009 Senegambia 892 361 118 6.93 ± 3.26 -1.60** 0.0037 0.0010 Sierra Leone 823 343 110 7.21 ± 3.38 -1.48* 0.0035 0.0016 Gold Coast 505 223 96 6.64 ± 3.14 -1.53* 0.0045 0.0007 Bight of Benin 421 196 97 6.75 ± 3.18 -1.58** 0.0048 0.0009 Bight of Biafra 3641 852 149 8.90 ± 4.10 -1.27* 0.0024 0.0014 West-central Africa 1403 370 122 9.05 ± 4.17 -1.15 0.0036 0.0004 South-east Africa 775 228 103 8.50 ± 3.94 -1.14 0.0038 0.0008 East Africa 805 402 139 8.76 ± 4.05 -1.55* 0.0043 0.0005 * p-value < 0.05 ** p-value < 0.02 k = number of distinct haplotypes S = number of polymorphic sites θπ ± SD = mean number of pairwise differences D = Tajima's D RI raggedness index SSD sum of square deviations
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Post by Admin on Jun 10, 2021 21:16:48 GMT
Discussion The African Diaspora in Jamaica is the result of a well-documented trade in human lives for just over 150 years motivated almost entirely by the rise in demand for luxury goods in Western Europe. By taking historical African embarkation points into account, we compared estimates of maternal contribution of each parental population with historical disembarkation records. The results of the admixture analysis suggest the mtDNA haplogroup profile distribution of Jamaica more closely resembles that of aggregated populations from the modern day Gold Coast region despite an increasing influx of individuals from both the Bight of Biafra and West-central Africa during the final years of the trade. When taking what is known about the negative rate of natural population growth of slaves on Jamaica, these results add an additional layer of complexity to demographic history of Jamaica. Planters found it more economical to import new labour rather than invest in natural reproduction within their existing groups. Coupling low fecundity with the high mortality leads to the expectation of a fluid demographic shift through time to a haplogroup profile distribution more closely resembling those groups arriving later during the slave trade. Present results do not show this, hinting instead at non-random processes in the creation of modern Jamaican matrilineal demography.
The admixture results may suggest a preference among Jamaican planters. Historic evidence suggests the Jamaican planting class held the Akan of the Gold Coast in very high regards [23], although similar anecdotal evidence is mixed [24]. Individual planters may have had ethnic preferences, although it would have been unwise to ignore immediate labour demands. The Jamaican slave market was typified by large purchasers competing for limited number of Africans [24]. The sale of slaves in Kingston, Jamaica's main slaving port, was characterized by timing and market savvy. Prices varied considerably. Often the most desirable slaves were sold at the beginning of the sale in very small numbers for well over the average price of the total sale [25]. As the sale progressed, prices dropped, and often Kingston merchants would make very large purchases for less than the price as a whole. These slaves would then be transported to urban yards to be acclimatized to Jamaica and slavery with individuals from other shipments, and then resold for a profit to planters [24]. The whole process would have resulted in a more heterogeneous cultural mix even before reaching their final destination.
The entire acclimatization process was understandably both mentally and physically stressful for newly arriving Africans. Between a quarter to a half of newly landed Africans died within the first three years on the island [26]. The distance and time individuals spent travelling is negatively correlated with survival [27]; as such, individuals embarking at ports further from Jamaica would be expected to arrive in a more poorly state. It can postulated therefore that despite more than half of all Africans shipped to Jamaica coming from the Bight of Biafra, they may have not survived the acclimatization process as frequently as those individuals from further west along the coast. Individuals arriving from Southeast Africa and Madagascar were significantly disadvantaged in this respect, perhaps evidenced by their negligible contribution to the mtDNA pool of Jamaica.
The slave society on Jamaica also operated in a very rigid social hierarchy; creole slaves had much greater life expectancy, fecundity, and upward social mobility than those born in Africa [3]. The entire society was also highly endogamous, the one glaring omission being the high frequency in which white men fathered children with their slaves, providing an opportunity for intergenerational mobility. Slaves born of mixed parentage were more often the recipients of more favourable positions, including domestics and tradesmen. Slaves of colour were also much more likely to be manumitted by their owners [28]. Considering the estimated paternal contribution by Europeans for modern Jamaicans is estimated at just over 40% [10], African-European admixture may have played an important role in the legacy of the slave population.
The development of modern Jamaican English may also provide insight into the demographic development of the island. The modern creolized English spoken on the island has been traced to relatively uneducated Northern British and Irish overseers and bookmakers and the early African slaves they interacted with. During the initial era of slavery on the island (1655-1700), slave acculturation was a process characterized by direct contact between newly arrived Africans and their European overseers. Though the Gold Coast contributed marginally to the slave trade prior to 1700, the Akan speaking groups from modern Ghana were thought to be the largest concentrated linguistic groups [29]. These early slaves heavily influenced the development of the Creole slave language and culture on the island [30]. Additionally, modern Jamaican English contains many loanwords of African origin, a majority of those etymologically from Gold Coast region [31]. A large part of the pidginization is thought to have been completed within the first few decades, and as the proportion of Europeans began to shrink with the explosive increase in slave imports, newly arrived Africans would be more reliant on established slaves for the acquisition of a common tongue [32]. Contemporary accounts of a 'two-burial' custom also match those found in groups from the Gold Coast [33]. Africans arriving from the Gold Coast may have thus found the acclimatization and acculturation process less stressful because of cultural and linguistic commonalities, leading ultimately to a greater chance of survivorship and a greater number of progeny.
Conclusions In summation, despite the historical evidence that an overwhelming majority of slaves were sent from the Bight of Biafra and West-central Africa near the end of the British slave trade, the mtDNA haplogroup profile of modern Jamaicans show a greater affinity with groups found in the present day Gold Coast region. Caution must be paid however to the scope of the analyses performed here. The Jamaican slave markets were the largest in the West Indies and sporadic accounts exist of slaves being purchase in Jamaica for plantations in other part of the New World; however, it is difficult to accurately trace the ancestry of the resold slaves. Additionally, after the abolition of slavery in 1834, the island is treated here as roughly a closed system with regards to the African continent. The trajectory of the mtDNA distribution is assumed to have stayed relatively consistent since emancipation; however, constraints imposed on the Jamaican population may have changed through time, influencing modern demography. The end of the slave trade in Jamaica brought about a change in economic climate, with a small albeit recognizable amount of Jamaicans emigrating to other parts of the world, as well as foreign migrant labours arriving from around the globe. Whether any these constraints have significantly affected the mtDNA distribution on the island is difficult to say.
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Post by Admin on Jun 11, 2021 21:00:31 GMT
Y-Chromosomal Diversity in Haiti and Jamaica: Contrasting Levels of Sex-Biased Gene Flow
The islands of the Caribbean are partitioned into three main groups: (1) the Greater Antilles, which consists of Cuba, Hispaniola (currently segregated into Haiti and the Dominican Republic), Jamaica, and Puerto Rico; (2) the Lesser Antilles, an archipelago that lies to the west of Puerto Rico, comprised of numerous smaller volcanic and rift islands; and (3) the Lucayan chain, which includes the Bahamas and the Turks and Caicos Islands. In the present study, we focus on Haiti and Jamaica, two countries that, although they shared their initial 170 years of colonization by Spain, differ markedly in their subsequent demographic histories. A pivotal and dramatic chapter of both countries’ histories, however, involved the importation of hundreds of thousands of African slaves during the Transatlantic Slave Trade, an event that contributed to the rich diversity of African cultures, nations, tribes, languages, religions, and customs in these newly established European colonies. Yet, it is approximated that about 50% of the African captives died within a few years of their arrival, as a result of the psychological shock of becoming slaves and the extreme deplorable laboring conditions that worked them to death (Fick, 1990). Jamaica was captured from Spain by the British in 1655 (Mordecai and Mordecai, 2001) and ultimately transformed into one of the Caribbean’s leading sugar producers by the early nineteenth century (Rogozin´ ski, 1999). To meet the labor demands associated with this rise in prosperity, white bond-servants (Henriques, 1964; Hurwitz and Hurwitz, 1971) were imported from Europe (i.e., Welsh, Scottish, and Irish) to Jamaica where they served as the initial labor force but were soon replaced by the 914,902 enslaved Africans transported to the island during the Transatlantic Slave Trade (Pepin, 2005). According to Higman (1995), Jamaica housed one of the largest African slave populations throughout the British Caribbean, the majority of which originated from the Bight of Biafra and Central Africa (1792–1807). However, once slavery was abolished and the African slaves were emancipated, Jamaican plantation owners had to turn elsewhere to supplement the dwindling labor force. As a result, workers from Western Europe (primarily Britain and Germany; Henriques, 1964), continental Africa (including Sierra Leone and Central Africa; Mordecai and Mordecai, 2001), China (i.e., Kwangtung/ Guangdong province and Hong Kong; Lai, 1990, 1998) and South India (Henriques, 1964) were contracted as part of the Indentured Labor System (1838–1918).
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Post by Admin on Jun 12, 2021 3:09:35 GMT
Haiti, in contrast, was occupied by the French in 1697 through the signing of the Treaty of Ryswick (Coupeau, 2008). As a French colony, Haiti (formerly referred to as St. Domingue) emerged as the largest sugar and coffee producer in the world (Knight, 2000), and as a consequence, an estimated 860,000 African laborers were imported into the country between 1681 and 1791 (Coupeau, 2008). Although the first captives on record were Muslims originating primarily from Senegal (16th century), most enslaved Africans that arrived in Haiti during the 17th and 18th centuries had disembarked from the Gulf of Guinea, the Ivory Coast, the Gold Coast (Ghana) and the Slave Coast (Togo, Benin and Nigeria). It was not until the latter part of the 18th century that laborers native to West Central Africa (Congo and Angola) and the African east coast (i.e., Mozambique) were transported to the island. It is noteworthy that in the French Caribbean, as opposed to the colonies controlled by Britain, concubinage between the French planters and their African-born female slaves was prevalent. In Haiti, this practice led to a dramatic rise in the number of Affranchis (mulattoes), who by 1789 (27,000) were almost equal in number to the Blancs (West European) present in the country and outnumbered the Western European sector of the remaining French and British Caribbean colonies combined (Fick, 1990). Although many of the Affranchis in Haiti were granted their freedom, this group, along with the Noirs (African slaves), were considered inferior to the Blancs. The rigid social structure and intense discrimination imposed by the French colonists ignited the war for independence, which ultimately resulted in Haiti’s independence in 1804 (Coupeau, 2008). have been increasingly utilized to examine the patrilineal influences in highly admixed groups (Vallone and Butler, 2004; Hammer et al., 2006; Harris et al., 2006; Gonza´lez-Andrade et al., 2007; Hu¨ nemeier et al., 2007; Sims et al., 2007; Gonc¸alves et al., 2008; Mendizabal et al., 2008; Stefflova et al., 2009; Nun˜ ez et al., 2010; Simms et al., 2011, Benn Torres et al., 2012), such as those residing in the Caribbean. In one of the earliest studies, Harris and collaborators (2006) reported that more than 80% of the Barbadian paternal gene pool is derived from continental African sources (i.e., exhibiting haplogroups E1*, E3*, and E3a, which are currently classified as E1a-M33, E1b1-P2, and E1b1a-M2, respectively), whereas the remaining patrilineages in this collection are of Eurasian origin (i.e., haplogroups K* and R1b, the latter of which was reclassified as R1b1b1- M269 by Myres et al., 2011). Strong South-Saharan African genetic signals were also detected in populations throughout the English-speaking Caribbean using the DYS 287 polymorphism, with contributions from Africa ranging from 34.1% in Dominica to 88.3% in the island of St. Kitts (Benn Torres et al., 2007). Additionally, the Y-haplogroup distributions of five of the six Bahamian populations examined in our earlier study (Simms et al., 2011) indicate high frequencies of South-Saharan African- specific lineages (A1b-V152, B-M60, E1a-M33, E1b1a-M2, and E2b-M98), which range from 71.2% in Abaco to 79.7% in Exuma. The prominent SouthSaharan African genetic influences in the various Caribbean islands is anticipated given the magnitude of slaves transported to them during the Transatlantic Slave Trade (Eltis, 2001; Pepin, 2005; Coupeau, 2008). The Bahamian group from Long Island, in contrast, was characterized by higher frequencies of European-specific haplogroups (74.4%) and much lower proportions of African Y-chromosomes (Simms et al., 2011), paralleling the Y-haplogroup substructure of Cuba, where 78.8% of the population exhibits European patrilineages, compared to only 19.7% and 1.5% that possess African and East Asian chromosomes, respectively (Mendizabal et al., 2008). The available data, however, is fragmentary, with the paternal structure of many populations throughout the region still genetically undefined. Mitochondrial DNA studies, although limited, reveal a predominantly South-Saharan African or Native American specific maternal component for the populations from the Caribbean. The collections from Grenada, St. Kitts, St. Lucia, Dominica, St. Vincent, and Trinidad, for instance, were found to possess elevated levels (72.0%– 97.9%) of haplogroup L subclades, which are common among African populations south of the Sahara Desert, and varying degrees of genetic input from Eurasian (i.e., haplogroups H, K, M, N, and U) and, in the case of Dominica, St. Vincent and Trinidad, Native American (i.e., haplogroups A, C, and D) sources (Benn Torres et al., 2007). The findings published by Mendizabal et al. (2008) and Deason et al. (2012), also indicate strong African genetic signals in the maternal gene pools of Cuba (45.3%) and Jamaica (97.5%), respectively, although the former population, in contrast to the latter, exhibits much higher frequencies of European (21.6% in Cuba vs. 2.5% in Jamaica) and Native American (33.1% in Cuba vs. 1.0% in Jamaica) haplogroups. However, of all the Caribbean populations analyzed thus far, Aruba (ToroLabrador et al., 2003) and Puerto Rico (Martı´nezCruzado et al., 2005) were found to possess the highest frequency of Amerindian-specific matrilineages, with haplogroups A, B, C, and D constituting 81.3% and 61.1% of each collection’s maternal gene pool, respectively. Evidence of sex-biased gene flow in humans is welldocumented in populations from the Americas, including several island nations throughout the Caribbean basin (Benn Torres et al., 2007; Mendizabal et al., 2008; Simms et al., 2011). The direction and pattern of the non-random inheritance is generally the same for these former colonies of Iberia, with Europeans serving as the predominant contributors of Y-chromosomes and Native among African Americans from the United States (US), where European haplogroups were found to comprise the majority of this group’s paternal gene pool whereas the mtDNA haplotypes present were of African origin (Gonc¸alves et al., 2007b; Stefflova et al., 2009). The levels of non-European maternal and paternal lineages detected in the US European population, in contrast, were minimal (Gonc¸alves et al., 2007b). Altogether, these studies illustrate that the direction and pattern of gene flow varies depending on the demographic history of the population being considered, particularly in instances where it is derived from colonization and/or slavery. To test this hypothesis, we embarked on a study that will assess the genetic composition and structure of Haiti and Jamaica, two Caribbean countries with divergent colonial histories. Specifically, we examined the impact of putative ancestral genetic sources on the countries in the context of their specific historical background utilizing 177 binary markers and 17 short tandem repeat (STR) loci on the non-recombining region of the Y-chromosome (NRY).
Americans or Africans as the primary source of maternal lineages (Carvajal-Carmona et al., 2000; Seielstad, 2000; Gonc¸alves et al., 2007b; Benn Torres et al., 2012). This asymmetric pattern of mating suggests that, at least during early colonial times, European men and Native American or African women were often the basis of the family unit, a finding consistent with historical records [e.g., a 1514 census reports that 40% of Spanish men in Hispaniola were married to Native American women (Fick, 1990)], which indicate that the majority of European colonists settling in the Americas were male (Sa´nchez-Albornoz, 1977; Nun˜ ez et al., 2010). The genetic data is congruent with these historical accounts in pointing out that, during the colonization process, most migrants from Spain and Portugal were without spouses, a situation that allowed for interracial marriages, and ultimately an increase in the portion of the population of mixed ancestry (i.e., mestizos and mulattoes). A similar distribution pattern was also note
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