Human Mating Systems

By Samantha Nemasango

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Evolutionary psychology are debating on whether humans are designed for monogamy, polygyny or extra marital relationship (Hazan and Zeifman, 1999)

Mating systems refers to how human and other animals form sexual relationships  4 types, monogamy, polygyny, polyandry, polygynandry or promiscuity ( Valsiner, 2000)
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Fig1: percentages of the mating systems

MONOGAMY
Mating system which involves one male and one female  2types of monogamy, perennial and serial  Perennial monogamy- pair bonds for life (Black,2001)  20% of world society are perennial monogamist
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Serial monogamydifferent partners throughout lifetime but one partner at a time (United States)

Fig2: male and female monogamy

16% of human society practising monogamy  E.g Mesopotamia, Romans and modern christians
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Monogamy may be the consequence of mate guarding  Males prevents food theft
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Reduces infanticide and sexual coercion  No sperm competition
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Humans are one of the 32 species with concealed ovulation Concealed ovulation is associated with monogamy

Fig3: ratios of male and female in different mating systems

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Discourages man to search for another partner because he will not know who is fertile among them Females way of keeping males from killing their offspring (Rice, 2007) Increased paternal certainty and care Female lost estrous synchrony Fig 4: Fertility rate in mono / polygyny during evolution? Voices, facial attractiveness and body scent are the ways male spot females fertility (Roberts et al, 2004) Monogamy increases resources

Fig 5: mono and polygyny child mortality

POLYGYNY
Involves one male with multiple female mates  Sororal polygyny- sisters  Non sororal- females not related ( Lundeen, 1996)  Dominant mating system practised by 83% of human societies  Abrahamic traditionsMormonism, Liberians support polygyny
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Fig 6: how mating systems developed

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Benefits man by increasing reproductive rates
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Females marry 5years earlier  6.4 years is usually the age difference (Tertilt, 2005)

◦ Polygyny can reduce or increase fertility

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Factors that reduce fertility – marrying at an old age, marrying old men and conflict between co-wives Why female choose polygyny? Children of polygynous men had increased fertility, high enough to offset low fertility of women (Josephson, 2002)

Fig 7: polygynous man , 3 wives and children

Males monopolises access to their mates  Females benefit sharing a high status male
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Polygyny increases sexual dimorphism Females get shorter because they undergo early menarche in polygyny (Kanazawa, 2005)

Fig 8: Status influencing polygyny

POLYANDRY
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One female mating with multiple males

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Practised by 0.47% of human society The Tibetans, the Sherpa of Nepal, the Marquesans of Polynesia Benefited families by preserving large lands, supplementing inadequate labour (Weigel and Weigel, 1987) Sperm competition Males usually outnumber females in these societies

Fig 9: areas where polyandry is common

◦ Form of birth control-lower rates of population growth  Avoid dividing states and solidify wealth
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Limits male reproductive success

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Kin selection may play a role Fraternal polyandry is most common Males with parental capabilities and fitness are selected Sexual selection

Fig 10: fraternal polyandry of 3 brothers

Table 1: different types of polyandry TYPES OF POLYAND RY BROTHER S MARRIED AT THE SAME TIME OFFICIALL RIGHTS/ Y RESPONSI RECOGNIS BILITIES ED

FRATERNAL
ASSOCIATE D

YES
POSSIBLY

YES
NO

YES
YES

YES
YES

NONFRATERNAL
CICIBEISM/ NOT MARRIED

NO
POSSIBLY

NO
NO*

YES
NO

YES
NO

POLYGYNANDRY
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Group of males mating with group of females

It is a very rare but common in the Pahari society North India  Occurred in ancient Hawaii and Melanis  Partible paternity ( Mesoudi and Laland, 2007)  Developed from polyandrybrothers work together to feed their wife (Cartwright, 2000)  Sperm competition  Cooperation in rearing offspring  Offspring well cared for
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Fig 11: Group marriage / polygynandry

REFERENCES:
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Black M.J (2001) fitness consequences of long term pair bond: monogamy in extreme Volume 12 no5 International society for behavioural ecology Cartwright J (2000) evolution and human behaviour: Darwin perspectives on nature Press academy Flegr J, Harvlicek J, Hruskova M, Jones B.C, Little A.C, Perrett D.1, Petrie M, Roberts S.C (2004) female facial attractiveness increases during the fertile phase of menstrual cycle Volume 271 The royal society Hazan D, Zeifman K (1999) attachment, evolution and the psychology of religion The Guilford press. New York Josephson S.C (2002) does polygyny reduce fertility? Volume 14 issue 2 American journal of human biology pg. 222-232 Kanazawa S (2005) human sexual dimorphism in size may be triggered by environmental cues Volume 37 issue05 Journal of biosocial science Laland K, Mesoudi A (2007) culturally transmitted paternity, beliefs and evolution of human mating behaviour Volume 274 no 1645 The royal society Lundeen M.J (1996) women, polygyny and power Volume 13 Nebraska apologist. University of Nebraska-Lincoln Marlowe F(2000) paternal investment and human mating systems Volume 51: issue 1-3 Elsevier Moorad J.A(2011) evolution and human behaviour Volume 32, issue 2 Muehlenbein M.P (2010) human evolutionary biology Cambridge press academy Rice M.E(2007) children killed by genetic parents versus step parents Volume 28 issue 2 Evolution and human behaviour. Elsevier Roberts S.C, (2004) Sharma D.D(2000) customs and rights of the Himalayan people Mittal publications Starkweather M.E (2010) exploration into human polyandry: an evolutionary examination of non classical classes Volume 23 No 2 Human nature Tertilt M (2005) polygyny, fertility and saving Volume 113, no 6 Journal of political economy Weigel R.M, Weigel M.M(1987) demographic factor affecting the fitness of polyandry for human male: a mathematical model and computer model Volume 8, issue 2 Ethology and socio-biology. Elsevier