Imbalanced numbers of men and women in societies or social groups (i.e. sex ratios) have been linked to a variety of social consequences. Studies report associations with relationship formation patterns and timing, divorce rates, fertility timing and rates, sexual norms, female labour market participation as well as violence and aggression. Theoretical arguments commonly start from a social exchange perspective, considering the sex ratio as a factor shaping individuals’ dyadic power both on the partner market and within relationships. Consequentially, behavioural consequences are theorized to result for these power and opportunity cost imbalances. However, theoretical reasoning remains unclear about whether behavioural consequences result from individuals’ deliberate adjustment of partner market strategies or unconscious endocrinal or normative variations. We fill this causal gap using longitudinal pairfam data to analyse correlations between local and perceived sex ratios in Germany. Our results show that correlation between individuals’ perception of sex ratios in daily life interactions and local sex ratios is very low. Results are robust for a variety of operationalisations for local sex ratios and essentially the same for municipality and county level. Additionally, we analyse transitions into relationships and find significant effects of local sex ratios only for women, while subjective sex ratios show significant effects. Our models show that local and perceived sex ratio effect estimates are independent, corroborating our prior finding. In sum, our findings suggest that local and subjective sex ratio are independent of one another. Consequently, sex ratio effects on behavioural outcomes are rather unlikely to be due to conscious strategy adjustments. Subjective partner availability and local sex ratios appear to be separate factors, questioning stated mechanisms of sex ratio effects on behavioural outcomes via optimizing choices. Instead, local sex ratios may affect relationship formation via processes not observed by individuals.

Imbalanced numbers of men and women in societies or social groups (i.e. sex ratios) have been linked to a variety of social consequences. Studies from the demographic and biology of human behaviour literature report associations with union formation patterns and timing, divorce rates, fertility timing and rates, sexual norms, female labour market participation as well as violence and aggression (see eg. Dyson 2012; Schacht et al. 2017; Stone 2017). Theoretical reasoning commonly starts from a social exchange perspective, assuming that individuals maximize their returns by choosing the best available partner given their own attractiveness – physically but also in terms of social status. The sex ratio is considered to reflect the overall partner availability, representing opportunity costs of relationships that shape dyadic power between (potential) partners within a relationship or on the partner market (Guttentag and Secord 1983). If choices are limited (abundant) in a skewed sex ratio partner market, individuals may lower (raise) their standards for potential partners, prefer an earlier (later) entry into relationships and their relationship stability and commitment may be affected. Yet theoretical reasoning concerning the effects of imbalanced sex ratios remains unclear whether these result from deliberately chosen strategies or rather result from unconscious mechanisms, for example endocrinal and/or normative variations. This leaves a causal gap, since behavioural consequences of imbalanced sex ratios could either be mediated by partner market dynamics as imbalanced sex ratios result in more male or female singles. On the other hand, sex ratio effects could be due to selection mechanisms: for example in a high sex ratio environment, individuals may be exposed to male-skewed contexts more often than in the diametric scenario.

This study analyses whether perceived sex ratios correlate with local sex ratios on municipality and county level in Germany. Thus, we seek to contribute to the understanding of potential mechanisms that regulate social consequences of sex ratio. Most studies to date used administrative data, lacking subjective assessments of partner market dynamics. We use data from the first seven waves (2008-2015) of the Panel Analysis of Intimate Relationships and Family Dynamics (pairfam), a longitudinal survey of partnership and family dynamics of three German birth cohorts (1971-73, 1981-83, 1991-93), offering individual-level and subjective partner dynamic data. Specifically, we use an indicator of perceived sex ratios answered by respondents who identified as heterosexual singles actively looking for a partner. In view of differential calculations of sex ratios in the literature, we test a variety of operationalisations: 3-, 4-, 6-, and 10-year age ranges with no, 1-year and 2-year age shifts between male and female cohorts. In addition, we also test variants of the adult sex ratio with age spans from 15 to 39 and from 15 to 49, respectively. Moreover, we use counties and equivalent city entities (Landkreise und Kreisfreie Städte) as well as municipalities (Gemeinden) as local partner market units. Our results show that local sex ratios and perceived sex ratios correlate very low with each other: Values of Spearman’s ρ fail to exceed .01 for any of the operationalisations of local sex ratios. Furthermore, results remain the same when using a categorized version of local sex ratios as female-skewed, (nearly) balanced, and male-skewed. What is more, results are the same for men and women.

This finding is corroborated by a multi-level discrete time event history analysis of transitions into relationships. Controlling for age, age-squared, education, employment status, enrolment status, relationship experience, eastern locality, and parenthood, we find that favourable subjective sex ratios are significantly associated with a higher likelihood of transition into a relationship. Local sex ratios however only proved to be significant for women’s transitions only. Consistent with our prior finding, both sex ratio measure’s estimates are invariant against adding/dropping the other from the model.

In sum, our findings suggest that local and subjective sex ratio are independent of one another. Consequently, sex ratio effects on behavioural outcomes are rather unlikely to be due to conscious strategy adjustments. Subjective partner availability and local sex ratios appear to be separate factors, questioning stated mechanisms of sex ratio effects on behavioural outcomes via optimizing choices. Instead, local sex ratios may affect relationship formation via processes not observed by individuals.

Dyson, Tim. 2012. “Causes and Consequences of Skewed Sex Ratios.” Annual Review of Sociology 38(1):443–61.

Guttentag, Marcia and Paul F. Secord. 1983. Too Many Women? The Sex Ratio Question. Beverly Hills, CA: SAGE.

Schacht, Ryan, Karen L. Kramer, Tamás Székely, and Peter M. Kappeler, eds. 2017. “Adult Sex Ratios and Reproductive Strategies: A Critical Re-Examination of Sex Differences in Human and Animal Societies [Theme Issue].” Phil. Trans. R. Soc. B 372(1729).

Stone, Emily A. 2017. “Do Women Compete for Mates When Men Are Scarce?” Pp. 249–64 in The Oxford Handbook of Women and Competition, edited by M. L. Fisher. New York: Oxford University Press.