The Fish is the Friend of Matriliny: Reef density predicts ... · The Fish is the Friend of...

The Fish is the Friend of Matriliny: Reef densitypredicts matrilineal inheritance across the world and its

persistence in Melanesia

Ariel BenYishay, Pauline Grosjean and Joseph Vecci

WMC, UNSW and Monash University

ANU: July 2015

BGV (WMC, UNSW and Monash) July 2015 1 / 32

Introduction

Matrilineal Inheritance

Historical gender norms can influence behaviour

Matrilineal Inheritance– Land is transferred to daughter.

Female land rights and ownership affects many outcomes

Fertility, female bargaining power, sex biased mortality, public goodsprovision (Chattopadhyay & Duflo 2004, Qian 2008, Alesina et al.2013)

Productivity, economic efficiency, effectiveness of land reform(Goldstein & Udry 2008, Deininger et al. 2013)

Gender differences often related to social norms–ingrained behaviour

Culture and genetic diversity affects–Growth (Ashraf & Galor 2011,2013), innovation adoption (Spolaore & Wagziarg 2009), conflict(Spolaore & Wagziarg 2009).

Introduction

Matrilineal Inheritance

Historical gender norms can influence behaviour

Matrilineal Inheritance– Land is transferred to daughter.

Female land rights and ownership affects many outcomes

Fertility, female bargaining power, sex biased mortality, public goodsprovision (Chattopadhyay & Duflo 2004, Qian 2008, Alesina et al.2013)

Productivity, economic efficiency, effectiveness of land reform(Goldstein & Udry 2008, Deininger et al. 2013)

Gender differences often related to social norms–ingrained behaviour

Culture and genetic diversity affects–Growth (Ashraf & Galor 2011,2013), innovation adoption (Spolaore & Wagziarg 2009), conflict(Spolaore & Wagziarg 2009).

Introduction

Matrilineal InheritanceSource:Standard Cross Cultural Sample (Murdock and White 1969)

Introduction

Key Research Question: the origins of matrilinealinheritance

What determines the norm society adopts?

Social organisation and in particular inheritance rules is a evolutionaryoutcome of a process of vertical decent, in which norms are inheritedfrom parents and parents’ societies, with adaptation to ecologicalconditions (Kaplaan et al 2009)

Our analysis concerns the transition away from matrilineal inheritanceto patrilineal inheritance

Introduction

Approach

1 Examine correlation between worldwide matrilineal inheritance andreef density.

2 Do the same for the Solomon Islands

3 Control for culture

4 Examine demographic consequences of matrilineal inheritance.

Introduction

Contributions

1. Show that persistence in matrilineal inheritance is due to adaptation,independently of vertical decent

Prior work has not identified whether this correlation is the result ofadaptation to ecological conditions. In comparative studies this iscalled habitat selection.

2. New, exogenous measure of reliance on fishing: reef density

3. Establish association between reliance on fishing and prevalence ofmatriliny

Introduction

Contributions

Introduction

Contributions

Introduction

Current literature- inheritance rules

Three determinants of prevalance of patrilineal vs matrilinealinheritance

Sexual division of labour-specialisation (Burton et al. (1984) Kaplan,et al. (2009))

Economic incentives

Evolutionary benefits of transmitting wealth to sons vs daughters forreproductive fitness

Paternity uncertainty

All are influenced by ecological conditions

Horticulture (farming without ploughs or large livestock): ”The cow isthe enemy of matriliny” (Aberle 1961, p.680).

Reliance on fishing has also been associated with matriliny

Ancedotal evidence on proximity to fisheries

Introduction

Current literature- inheritance rules

Three determinants of prevalance of patrilineal vs matrilinealinheritance

Sexual division of labour-specialisation (Burton et al. (1984) Kaplan,et al. (2009))

Economic incentives

Evolutionary benefits of transmitting wealth to sons vs daughters forreproductive fitness

Paternity uncertainty

All are influenced by ecological conditions

Horticulture (farming without ploughs or large livestock): ”The cow isthe enemy of matriliny” (Aberle 1961, p.680).

Reliance on fishing has also been associated with matriliny

Ancedotal evidence on proximity to fisheries

Introduction

Why Fishing and Matriliny?

here proximity to fisheries is higher :

Sexual division of labour: malespecialization in fishing, female inhorticulture; daughters as residualclaimants to landLand relatively less important as anasset, especially for men: only weaklyincreases sons’ reproductive fitness.Fishing entails high risk and absencemakes paternity less certain.

Three data sets:1) Standard Cross Cultural Sample (Murdock and White 1969): 186societies across the world

Among these societies, 16% are matrilineal

2) Original micro data from Solomon Islands (Village survey): randomsample of 59 villages in 3 provinces.

Small (488 people), remote (8 hours from provincial capital), coastallowlands villagesSubsistence fishing and horticultureFishing exclusively a male activity by paddleboat or male operatedcanoes (dangerous)20% of sample matrilineal

3) Global Distribution of Coral Reefs (UNEP 2010): Information ontype of coral reef and area

Use a distance algorithm to calculate the density of coral reefs in a10km radius of each each society/village.

Why Solomon Islands?

Matrilineal inheritance among Austronesian-speaking societies of thePacific are:

Ancestral (Hage and Marck (2003), (Jordan et al (2009). ContrastsEurasiaMore common today

Variation within small geographic areas, and even within ethnicgroups. Allows us to control for culture (unlike SCCS)

Preserved ways of life of small horticultural, fishing societies sincecirca 3,450 BP

No know patrilineal neighbours

Reef Islands

Solomon Islands

Western Province

Empirical Results

Fishing and gender

Need to establish:

Whether males fish in this context

Whether reef density is correlated with fishing

Empirical Results

Fishing and gender

Do males fish?

In the Murdock SCCS dataset, women are in charge of fishing in 5%of societies.

In our Solomon Island sample, males are 10 percentage points, or50%, more likely to earn an income from the sea compared tofemales; and conversely, females are 10 percentage points more likelyto earn an income from farming compared to men.

Fishing is a male activity

Empirical Results

Reef’s and fishing

Coral reefs are an important source of nutrients that are essential formarine organisms.

Coral reefs occupy less than 0.1% of the oceans surface yet they arethe habitat for over one-third of the worlds marine fishes (UNEP,2010)

Correlation in the Murdock SCCS dataset between ’Square Km ofReef’ and dependence on fishing is positive and statisticallysignificant at the 1%

Empirical Results

Reef Density and matrilineal inheritance across the worldand in Solomon Islands

Empirical Results

Phylogenetic Approach

Examines the evolutionary relationship between populations

Linguistic similarity may serve as a valid proxy for cultural similaritybecause of shared history (Guglielmo et al. 1995)

Include controls for language fixed effects

Empirical Results

Phylogenetic ApproachSource:Ethnologue

Empirical Results

Phylogenetic ApproachSource:Ethnologue

Empirical Results

Matriliny and Reef Density

Matrilineal inheritance(1) (2) (3)

Number of shallow reefs in 10km radius 0.006*** 0.005*** 0.006**(0.002) (0.002) (0.003)

Religion and political controls no no yes

Language group fixed effects no yes yes

Sample Size 58 56 52

R-Square 0.196 0.337 0.526

This is a 2.5% increase at the mean.Religion and political controls: main religion in village: Anglican, Catholic, Charismatic,Methodist, or other; elected leader, traditional village chief, village committee, or other;share of HH living solely from subsistence.Notes: OLS regression with robust standard errors corrected for heteroskedasticity arereported in parenthesis. ***, **, indicate statistical significance at the 1% and 5% level,respectively.BGV (WMC, UNSW and Monash) July 2015 23 / 32

Empirical Results

Demographic Implications

Evolutionary forces

Reproductive fitness and paternity uncertainty → smaller HHs

Economic incentives:

Higher productivity for female horticultural labor → smaller HHs

Empirical Results

Demographic Implications

Total Number of People in Village Household size(1) (2) (3) (4) (5) (6)

Matrilineal inheritance -240.70** -381.04** -352.33+ -4.53+ -5.72+ -10.05*(112.54) (185.10) (218.51) (2.78) (3.44) (5.45)

Religion and political controls no no yes no no yes

Language group fixed effects no yes yes no yes yes

Sample Size 57 56 52 57 56 52

R-Square 0.025 0.055 0.289 0.016 0.068 0.143

Religion and political controls: main religion in village: Anglican, Catholic, Charismatic, Methodist, or other; electedleader, traditional village chief, village committee, or other; share of HH living solely from subsistence.

Notes: The unit of observation is a village. OLS regression with robust standard errors corrected for heteroskedasticityare reported in parenthesis. ***, **, * and + indicate statistical significance at the 1%, 5% and 10%, 15% level,respectively.

Empirical Results

Village infrastructure

Collect information on access to public goods such as sanitation,water, primary schools, health and electricity

Males may fish because it has higher returns- control decision making

Results:

No difference in community access to: electricity; sanitation, water,health centres, primary schools

We find matrilineal villages have greater access to markets and roads

Empirical Results

Results:

Empirical Results

Results:

Empirical Results

Household Decision Making

Greater female control of assets may lead to greater householddecision making

Do females have more bargaining power in matrilineal villages?

Gender inequality is more pronounced where men perform most of theagricultural labour

We conduct a household survey, selecting 10 households per village.Survey both men and women 600 households

Results: In Matrilineal Villages-

Females are less likely to report that they feel worried or cheated

No difference in involvement of women in decision making in RDP

Females are equally likely to ask spouse for permission to sell an assetas patrilineal villages

Empirical Results

Household Decision Making

Greater female control of assets may lead to greater householddecision making

Do females have more bargaining power in matrilineal villages?

Gender inequality is more pronounced where men perform most of theagricultural labour

We conduct a household survey, selecting 10 households per village.Survey both men and women 600 households

Results: In Matrilineal Villages-

Females are less likely to report that they feel worried or cheated

No difference in involvement of women in decision making in RDP

Females are equally likely to ask spouse for permission to sell an assetas patrilineal villages

Empirical Results

RobustnessSoil Production

We find that women are more involved in agriculture in SI. Are wemeasuring the effects of fishing or horticulture on inheritancepractices?

Land quality could be lower in areas closer to reefs

Soil Production Index: considers the suitability of the best adaptedcrop to each soil’s condition in an area (FAO,2007)

Spatial resolution of 5 * 5 arc minutes

Empirical Results

RobustnessSoil Production

Empirical Results

RobustnessSoil Production:Western Province

Empirical Results

Robustness

Selection Bias (Habitat Selection): Oster (2013) test-based on therecommended assumption that the maximum R-squared is 1.3 timesthe R-squared obtained with the full set of controls, the influence ofunobservable variables would need to be more than 22 times as largeas the influence of all controls included in Column (3) to explain awaythe influence of reef density as a predictor of the persistence ofmatriliny.

Wild custer bootrap method- We re-estimate the model clustering bylanguage group. We alter the distribution of weights in the bootstrapto a six-point distribution. Using this method, we find almostidentical standard errors as the standard model

Use Conley (1999) and estimate a spatial model of dependence.

Empirical Results

Robustness

Selection Bias (Habitat Selection): Oster (2013) test-based on therecommended assumption that the maximum R-squared is 1.3 timesthe R-squared obtained with the full set of controls, the influence ofunobservable variables would need to be more than 22 times as largeas the influence of all controls included in Column (3) to explain awaythe influence of reef density as a predictor of the persistence ofmatriliny.

Wild custer bootrap method- We re-estimate the model clustering bylanguage group. We alter the distribution of weights in the bootstrapto a six-point distribution. Using this method, we find almostidentical standard errors as the standard model

Use Conley (1999) and estimate a spatial model of dependence.

Conclusion

Conclusions

Our results establish that ecological conditions play a central role inthe evolution of inheritance rules: both ecological factors andphylogenesis explain 40% of variation in prevalence of matrilinealinheritance in Solomon sample

First paper to establish reef density and, indirectly, reliance on fishing,as a robust predictor of persistence of matrilineal inheritance,independently of vertical descent

Contribute to recent literature on enduring effects of geographicendowments on relative outcomes of males vs. females, on culturalnorms, and on genetic diversity.

Conclusion

Conclusions

Conclusion

Conclusions

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