5-HTTLPR Genetic Diversity and Mode of Subsistence inNative Americans

Rafael Bisso-Machado,1 Virginia Ramallo,1 Eduardo Tarazona-Santos,2 Francisco M. Salzano,1 MariaC�atira Bortolini,1 and T�abita H€unemeier1*

1Departamento de Gen�etica, Instituto de Biociencias, Universidade Federal do Rio Grande do Sul, Porto Alegre91501-970, Rio Grande do Sul, Brazil2Departamento de Biologia Geral, Universidade Federal de Minas Gerais, Instituto de Ciencias Biol�ogicas, BeloHorizonte 31270-901, Minas Gerais, Brazil

KEY WORDS 5-HTTLPR; gene-culture coevolution; Amerindians; individualism-collectivism

ABSTRACT The relationship between the“individualism-collectivism” and the serotonin trans-porter functional polymorphism (5-HTTLPR), suggestedin the previous reports, was tested in Native SouthAmerindian populations. A total of 170 individuals from21 populations were genotyped for the 5-HTTLPRalleles. For comparative purposes, these populationswere classified as individualistic (recent history ofhunter–gathering) or collectivistic (agriculturalists).These two groups showed an almost identical S allelefrequency (75 and 76%, respectively). The analysis ofmolecular variance showed no structural differences

between them. Behavioral typologies like those sug-gested by JY Chiao and KD Blizinsky (Proc R Soc B 277(2010) 529–537) are always a simplification of complexphenomena and should be regarded with caution. Inaddition, classification of a whole nation in the individu-alist/collectivist dichotomy is controversial. The focus onmodes of subsistence in preindustrial societies, as wastested here, may be a good alternative although thepostulated association between the 5-HTTLPR Sallele and the collectivist societies was not confirmed.Am J Phys Anthropol 000:000–000, 2013. VC 2013 Wiley

Periodicals, Inc.

A common variation in the 50 regulatory region of theSerotonin Transporter gene (5-HTTLPR) is probably thepolymorphism most extensively investigated for associa-tion to neuropsychiatric disorders as its long (L) alleledetermines a striking increase in serotonin levels (andtherefore be associated with lower amount of serotoninin the synaptic cleft owing to increased reuptake) whencompared to its complementary (S) form (Collier et al.,1996; Lesch et al., 1996; Way and Lieberman, 2010;Kenna et al., 2012). However, studies with this polymor-phism are not limited to those related to neuropsychiat-ric disorders and other medical conditions. Usingpredominantly cross-national comparisons Chiao andBlizinsky (2010), for example, suggested that S, a sup-posed social sensitivity allele, would be more frequent incollectivistic cultures, in which people would be highlyinterconnected, whereas the L variant would be morefrequent in individualistic societies, where the focus ison independence among persons. Eisenberg and Hayes(2011) criticized Chiao and Blizinsky’s article, but so farno preindustrial society had been investigated for thesuggested association.

We decided to fill this gap-typing DNA from SouthAmerindian and Native Arctic samples stored in ourDepartment for the above-indicated polymorphism. Tocompare our results with those obtained by Chiao andBlizinsky (2010), we followed a similar typologicalapproach, classifying the populations from which we hadsamples in two categories according to their mode ofsubsistence: a) those with a relatively recent history ofhunter–gathering; and b) agriculturalists. However, weused Triandis et al.’s (1990) classification rather thanthat of Hofstede (2001), adopted by Chiao and Blizinsky(2010). Triandis et al. (1990) directly connected hunter–

gathering and agriculturalists with individualistic andcollectivist practices, respectively, taking into accountseveral aspects which are related to these two modes ofsubsistence (ecology, social complexity, norms of ingroup/outgroup relationships, etc.). Hofstede’s (2001) schemepresents similar and other parameters, but it is moreappropriate to classify industrial societies than the typeof populations that we investigated in this study.

Needless to say, there is a whole spectrum of situa-tions that make the classification of a given society inthese two polar situations difficult. But if the geneticeffect was strong, a clear signal of difference wouldappear. We took this opportunity also to verify whetherthe allele frequencies in this system would show associa-tions with languages (an important indicator of culturaldifferences) and geography.

Grant sponsors: Coordenac~ao de Aperfeicoamento de Pessoal deN�ıvel Superior (CAPES), Conselho Nacional de DesenvolvimentoCient�ıfico e Tecnol�ogico (CNPq), Fundac~ao de Amparo �a Pesquisa doEstado do Rio Grande do Sul (FAPERGS), Programa de Apoio aN�ucleos de Excelencia (PRONEX).

*Correspondence to: T�abita H€unemeier, Programa de P�os-Gradu-ac~ao em Gen�etica e Biologia Molecular, Departamento de Gen�etica,Instituto de Biociencias, Universidade Federal do Rio Grande doSul, Caixa Postal 15053, 91501-970 Porto Alegre, RS, Brazil.E-mail: hunemeier@gmail.com

Received 8 February 2013; accepted 4 April 2013

DOI: 10.1002/ajpa.22286Published online in Wiley Online Library

(wileyonlinelibrary.com).

� 2013 WILEY PERIODICALS, INC.

AMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY 00:000–000 (2013)

A total of 170 individuals from 21 populations weregenotyped for the 5-HTTLPR alleles. Ethical approvalfor this study was provided by the Brazilian NationalEthics Commission (Protocol no. 123/1998), as well as byethics committees in the countries where the non-Brazil-ian samples were collected.

DNA was extracted from plasma and glycerolized redblood cells, as well as total blood stored in our laborato-ries as a result of the previous studies (review in Sal-zano, 2002) using the QIAampVR DNA Mini Kit(QIAGEN GmbH, Hilden, Germany). Primers and PCRconditions are as described in Caspi et al. (2003). Geno-typic frequencies were obtained by direct counting. Sta-tistical analyses were performed using Arlequin 3.5.1.2(Excoffier and Lischer, 2010).

Genotypic and allelic frequencies were calculated forthe populations individually (Table 1), and then theywere grouped by language and geography (Table 2).Prevalences of the S allele were high, generallybeing above 50%. These numbers are in accordancewith the studies made in Asian populations (fromwhich Native Americans derive) which show frequenciesof the same order of magnitude (Chiao and Blizinsky,2010).

No genetic structure was found between groups,regardless of the three classifications used: geography(P 5 0.410), language (P 5 0.570), or mode of subsist-ence (P 5 0.616) (Table 3). The amount of genetic vari-ation between groups (FCT) is virtually zero in allthree analyses. The variation within each specific pop-ulation remains much larger and covers most of the di-versity (around 92%), as expected, but the variationamong populations within groups (FSC) was statisti-cally significant in two (language and mode of subsist-ence) of the three different classifications. Therefore,significant differences can exist among populations

uniformly classified as agriculturalists, or as hunter–gatherers.

Mode of subsistence is a powerful factor that has actedin the processes of gene–culture coevolution (Gerbaultet al., 2011; H€unemeier et al., 2012a,b). This is owing tothe fact that the population structure of hunter–gather-ers and agriculturalists differs in many ways. Differen-ces in societies that adopt one or the other of these twomodes of subsistence have been extensively consideredby Salzano (1985), but briefly, they are different in

TABLE 1. Linguistic classification, geographical area, and mode of subsistence of 21 Asian and Native American populations stud-ied, with the 5-HTTLPR genotypic and allelic frequencies

Population (n) Languagea Geography Mode of subsistenceb

Genotypes Alleles

SS SL SL S L

Altaian (1) Altaic Asia Agriculturalists 1.00 1.00Buriat (1) Altaic Asia Agriculturalists 1.00 1.00Kalmyk (1) Altaic Asia Agriculturalists 1.00 1.00Siberian Eskimo (10) Eskimo–Aleut Asia Hunter–gatherers 0.30 0.30 0.40 0.45 0.55Apala�ı (33) Carib Amazonia Hunter–gatherers 0.55 0.27 0.18 0.68 0.32Arara (6) Carib Amazonia Hunter–gatherers 0.83 0.17 0.83 0.17Arawet�e (2) Tupi Amazonia Hunter–gatherers 1.00 1.00Gavi~ao (8) Tupi Amazonia Hunter–gatherers 0.88 0.12 0.88 0.12Guarani (24) Tupi Southern Brazil Agriculturalists 0.46 0.29 0.25 0.60 0.40Jamamadi (2) Arauan Amazonia Hunter–gatherers 0.50 0.50 0.50 0.50Karitiana (3) Tupi Amazonia Hunter–gatherers 0.33 0.67 0.17 0.83Kuben-Kran-Kegn (1) Macro-Ge Amazonia Hunter–gatherers 1.00 1.00Lengua (12) Mascoian Chaco Agriculturalists 1.00 1.00Parakan~a (1) Tupi Amazonia Hunter–gatherers 1.00 1.00Quechua (37) Quechuan Andes Agriculturalists 0.62 0.24 0.14 0.74 0.26Suru�ı (6) Tupi Amazonia Hunter–gatherers 0.83 0.17 0.83 0.17Tenharim (1) Tupi Amazonia Agriculturalists 1.00 1.00Wai-wai (8) Carib Amazonia Hunter–gatherers 1.00 1.00Xav�ante (5) Macro-Ge Brazilian Central Plateau Hunter–gatherers 1.00 1.00Xikrin (2) Macro-Ge Amazonia Hunter–gatherers 1.00 1.00Zor�o (6) Tupi Amazonia Hunter–gatherers 1.00 1.00

a Linguistic classification according to www.ethnologue.com.b Whether there was or there was not a relatively recent history of hunting–gathering.

TABLE 2. 5-HTTLPR genotypic and allelic frequencies groupedby language, geography, and mode of subsistence

Classification by Groupnames (number of populations/number of individuals)

Genotypes Alleles

SS SL LL S L

LanguageAltaic (3/3) 1.00 1.00Eskimo–Aleut (1/10) 0.30 0.30 0.40 0.45 0.55Carib (3/47) 0.66 0.19 0.15 0.76 0.24Tupi (8/51) 0.64 0.16 0.20 0.73 0.27Arauan (1/2) 0.50 0.50 0.50 0.50Macro-Ge (3/8) 1.00 1.00Mascoian (1/12) 1.00 1.00Quechuan (1/37) 0.62 0.24 0.14 0.74 0.26GeographyAsia (4/13) 0.46 0.23 0.31 0.58 0.42Amazonia (13/79) 0.72 0.13 0.15 0.78 0.22Southern Brazil (1/24) 0.46 0.29 0.25 0.60 0.40Chaco (1/12) 1.00 1.00Andes (1/37) 0.62 0.24 0.14 0.74 0.26Brazilian Central

Plateau (1/5)1.00 1.00

Mode of subsistenceAgriculturalists (15/77) 0.65 0.21 0.14 0.75 0.25Hunter–gatherers (6/93) 0.69 0.14 0.17 0.76 0.24

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American Journal of Physical Anthropology

population size, group mobility, fertility and mortalityparameters, population density and stability, housing,disease patterns, and vulnerability to environmentalchange. In this context, psychological and biological dif-ferences between hunter–gatherer (individualistic) andagriculturalist (collectivistic) populations could be devel-oped, but if they exist they were not reflected in the con-sidered dichotomy regarding 5-HTTLPR locus.

Collectivism and individualism involve a series of fac-tors, intrinsic to the individual (for instance, type of per-sonality, which is influenced by many hormones, as wellas by his/her life history) and extrinsic to him/her (suchas mode of subsistence, socio-cultural structure, withmore or less restrictive rules, types of hierarchy, and ide-ological goals). It would be difficult to imagine that asingle genetic factor could completely override theseother influences.

ACKNOWLEDGMENTS

The authors thank Caio Cesar Silva de Cerqueira for hishelp in early aspects of the statistical analyses, Sandro L.Bonatto and Dario Demarchi for donating the SiberianEskimo and Guarani samples, respectively. The authorsare also grateful to the individuals who donated the sam-ples analyzed here.

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TABLE 3. AMOVA for the partition of variance considering the three types of classification

Percentage of variation

Classification byAmonggroupsa

Amongpopulations

within-groupsWithin-

populations FSC (P-value) FST (P-value) FCT (P-value)

Languageb 20.22 8.40 91.8 0.084 (0.018 6 0.004) 0.082 (0.019 6 0.005) 0.002 (0.570 6 0.012)Geographyc 0.98 7.40 91.6 0.075 (0.126 6 0.010) 0.084 (0.016 6 0.005) 0.010 (0.410 6 0.013)Mode of subsistenced 22.43 9.67 92.8 0.094 (0.008 6 0.003) 0.072 (0.018 6 0.005) 0.024 (0.616 6 0.017)

a Note that negative values in the AMOVA are an indicative of excess of heterozygotes, such negative estimates should be inter-preted as zero (Excoffier and Lischer, 2010).b Eight groups: 1) Altaic: Altaian, Buriat, Kalmyk; 2) Eskimo–Aleut: Siberian Eskimo; 3) Carib: Apala�ı, Arara, Wai-wai; 4) Tupi:Arawet�e, Gavi~ao, Guarani, Karitiana, Parakan~a, Suru�ı, Tenharim, Zor�o; 5) Arauan: Jamamadi; 6) Macro-Ge: Kuben-Kran-Kegn,Xav�ante, Xikrin; 7) Mascoian: Lengua; 8) Quechuan: Quechua.c Six groups: Asia: Altaian, Buriat, Kalmyk, Siberian Eskimo; 2) Amazonia: Apala�ı, Arara, Wai-Wai, Suru�ı, Parakan~a, Tenharim,Zor�o, Gavi~ao, Arawet�e, Karitiana, Jamamadi, Xikrin, Kuben-Kran-Kegn; 3) Southern Brazil: Guarani; 4) Chaco: Lengua; 5) Andes:Quechua; 6) Brazilian Central Plateau: Xav�ante.d Two groups: 1) Agriculturalists: Siberian Eskimo, Apala�ı, Arara, Wai-Wai, Arawet�e, Gavi~ao, Karitiana, Parakan~a, Suru�ı, Zor�o,Jamamadi, Kuben-Kran-Kegn, Xav�ante, Xikrin, and Lengua; 2) Hunter–gatherers: Quechua, Guarani, Tenharim, Altaian, Buriat,and Kalmyk.

5-HTTLPR IN SOUTH AMERINDIANS 3

American Journal of Physical Anthropology