Sebastian Schnettler | Carl von Ossietzky University of Oldenburg (original) (raw)

Journal articles by Sebastian Schnettler

Objectives: This study examines if there exists a positive association between socioeconomic stat... more Objectives: This study examines if there exists a positive association between socioeconomic status and the proportion of male births in humans, as proposed by Trivers and Willard in 1973, using individual-level data drawn from the complete population of Sweden.

Methods: We examine more than 3,000,000 births between 1960 and 2007 using administrative register data with comprehensive information on various dimensions of socioeconomic status. We use six different operationalizations of socioeconomic status, including earnings, post-transfer income (including government allowances), wealth, parental wealth, educational level, and occupational class. We apply regression models that compare both changes in status for the same woman over time and differences in status across different women. We also measure socioeconomic status both at the year of child birth and the year of conception.

Results: Our results show the absence of any relationship between socioeconomic status and sex ratios, using a large number of different operationalizations of status.

Conclusions: We conclude that no substantive relationship between socioeconomic status and sex ratios exists for the population and period of our study.

Given increases in childlessness, we ask if and how the permanently childless substitute for adul... more Given increases in childlessness, we ask if and how the permanently childless substitute for adult children in their later-life support networks. Previous research finds that they are disadvantaged on several network and support indicators. Yet, the role of different substitution mechanisms remains unclear. We examine two substitution mechanisms: substitution through adjustments of network size/composition and through higher efficiency of personal ties. Data are from the German Ageing Survey (childless: N = 1,886; parents without/with residentially proximate children: N = 4,437/8,337). Our descriptive and regression results on network size/composition and the number of potential informational and emotional supporters show that both mechanisms play a role: the childless have more friends and extended kin, and they are more likely to consider them as potential supporters, than parents. Across cohorts or age groups, the relative effect size of network size/composition versus tie efficiency changes. Parents with no children nearby constitute a mixed type that shows similarities to the childless on some indicators of social support and to parents with at least one child nearby on other indicators. Our findings provide a foundation for better predicting how current demographic trends affect future scenarios of social support in later life and for identifying the future need for formal care services. Thus, they are relevant for social scientists and policy makers alike.

Environmental Health, Dec 2014

Background: The economic stress hypothesis (ESH) predicts decreases in the sex ratio at birth (SR... more Background: The economic stress hypothesis (ESH) predicts decreases in the sex ratio at birth (SRB) following economic decline. However, as many factors influence the SRB, this hypothesis is difficult to test empirically. Thus, researchers make use of quasi-experiments such as German reunification: The economy in East, but not in West Germany, underwent a rapid decline in 1991. A co-occurrence of a decline in the East German SRB in 1991 has been interpreted by some as support for the ESH. However, another explanation might be that the low SRB in 1991 stems from increased random variation in the East German SRB due to a drastically reduced number of births during the crisis. We look into this alternative random variation hypothesis (RVH) by re-examining the German case with more detailed data.

Methods: Our analysis has two parts. First, using aggregate-level birth register data for all births in the period between 1946 and 2011, we plot the quantum and variance of the SRB and the number of births and unemployment rates, separately for East and West Germany, and conduct a time series analysis on the East German SRB over time. Second, we model the odds for a male birth at the individual level in a multiple logistic regression (1991–2010, ~13.9 million births). Explanatory variables are related to the level of the individual birth, the mother of the child born, and the regional economic context.

Results: The aggregate-level analysis reveals a higher degree of variation of the SRB in East Germany. Deviations from the time trend occur in several years, seemingly unrelated to economic development, and the deviation in 1991 is not statistically significant. The individual-level analysis confirms that the 1991-drop in the East German SRB cannot directly be attributed to economic development and that there is no statistically significant effect of economic development on sex determination in East or West Germany.

Conclusion: Outcomes support the RVH but not the ESH. Furthermore, our results speak against a statistically significant effect of the reunification event itself on the East German SRB. We discuss the relative importance of behavioral and physiological responses to macro-level stressors, a distinction that may help integrate previously mixed findings.

Vor dem Hintergrund des demographischen Ungleichgewichts von Männern und Frauen in Asien beschäft... more Vor dem Hintergrund des demographischen Ungleichgewichts von Männern und Frauen in Asien beschäftigen sich diverse Autoren mit möglichen Konsequenzen eines Frauen- oder Männermangels, unter anderem für die Gewaltinzidenz in den betroffenen Gesellschaften oder Regionen. Allerdings präsentieren sich die bisherigen theoretischen Ansätze wie auch die empirische Evidenz als uneinheitlich. Der Beitrag gibt einen Überblick über sozialwissenschaftliche und evolutionstheoretische Perspektiven auf die Fragestellung und versucht diese zu integrieren. Darüber hinaus werden empirische Befunde dargestellt und eingeordnet sowie eigene Projekte vorgestellt und Forschungsdesiderata formuliert.

PLoS ONE, Feb 22, 2013

Based on evolutionary theory, Trivers & Willard (TW) predicted the existence of mechanisms that l... more Based on evolutionary theory, Trivers & Willard (TW) predicted the existence of mechanisms that lead parents with high levels of resources to bias offspring sex composition to favor sons and parents with low levels of resources to favor daughters. This hypothesis has been tested in samples of wealthy individuals but with mixed results. Here, I argue that both sample selection due to a high number of missing cases and a lacking specification of the timing of wealth accumulation contribute to this equivocal pattern. This study improves on both issues: First, analyses are based on a data set of U.S. billionaires with near-complete information on the sex of offspring. Second, subgroups of billionaires are distinguished according to the timing when they acquired their wealth. Informed by recent insights on the timing of a potential TW effect in animal studies, I state two hypotheses. First, billionaires have a higher share of male offspring than the general population. Second, this effect is larger for heirs and heiresses who are wealthy at the time of conception of all of their children than for self-made billionaires who acquired their wealth during their adult lives, that is, after some or all of their children have already been conceived. Results do not support the first hypothesis for all subgroups of billionaires. But for males, results are weakly consistent with the second hypothesis: Heirs but not self-made billionaires have a higher share of male offspring than the U.S. population. Heiresses, on the other hand, have a much lower share of male offspring than the U.S. average. This hints to a possible interplay of at least two mechanisms affecting sex composition. Implications for future research that would allow disentangling the distinct mechanisms are discussed.

Journal of Biosocial Science, Sep 2013

Based on evolutionary reasoning, Trivers & Willard (1973) predicted status-biased sex composition... more Based on evolutionary reasoning, Trivers & Willard (1973) predicted status-biased sex composition and parental investment with son-preferencing effects in higher, and daughter-preferencing effects in lower status groups. Previous research shows mixed results. This study uses event-history methods and Swedish register data to study one possible mechanism in isolation: do parents in different status groups vary in their proclivities to continue fertility based on the sex composition of previous offspring? The results show no support for the Trivers–Willard hypothesis on a wide range of different status indicators. Future research on the stated hypothesis should focus on physiological rather than behavioural mechanisms.

Journal of Family Research (Zeitschrift für Familienforschung), 2011

Consistent with inclusive fitness theory, evolutionary biologists predict that individuals care m... more Consistent with inclusive fitness theory, evolutionary biologists predict that individuals care more for their biological than their social children and hence that biological children assess the relationships to their parents better than stepchildren. To test this assumption, we use data from the U.S. National Longitudinal Study of Adolescent Health (Add Health). Unlike many other studies
that have been conducted so far, this survey allows us to analyze the consequences of the dynamic between social and biological parent-child relationships within the same families. We use
comparisons of sibling pairs and fixed-effects regression to achieve the within-family comparison. Both the descriptive and multivariate regression results confirm that – even after controlling for other relevant influences – biological parenthood
matters with regard to children’s relationship assessments (perceived parental care and closeness of the parent-child relationship) and in both the relationships to resident fathers and mothers. In the discussion, we comment on the possible inte-
gration of the evolutionary and sociological perspectives and close with some recommendations for future data collection that could allow researchers to analyze the relative impact of biological and social influences on parent-child relationships on a more fine-grained level.

Social Networks, 2009

Small-world studies were introduced by Milgram and others in the 1960s and 1970s. These studies, ... more Small-world studies were introduced by Milgram and others in the 1960s and 1970s. These studies, and a majority of variants conducted by others, display a number of methodological weaknesses that bias their results. While no explicit methodological standard exists for these studies, here I derive a number of best-practice criteria for small-world studies by pointing out mistakes of previous studies, and by applying methodological standards from other empirical research areas. Improving the methodology of letter referral studies is important, because such studies could still be useful in a number of contexts today, especially for the exploration of factors affecting targeted search processes.

Social Networks, 2009

This paper offers a structured overview of 50 years of small-world research. Initially formulated... more This paper offers a structured overview of 50 years of small-world research. Initially formulated by Pool and Kochen in the mid-1950s, the small-world concept can be divided into six research foci, based on three dimensions (structural, process-related, psychological), and two process-related themes (diffusion, search). Building on this analytical distinction, the article provides a historical summary of the different phases of research on the small-world problem, and summarizes the empirical and theoretical progress on different facets of the small-world phenomenon. The paper concludes with a brief assessment of accomplishments and open questions, suggesting some possible future research areas.

Books by Sebastian Schnettler

Special Issue 64, Kölner Zeitschrift für Soziologie und Sozialpsychologie, 2024

After a long neglect of biosocial and evolutionary approaches to human behavior and sociality in ... more After a long neglect of biosocial and evolutionary approaches to human behavior and sociality in sociology during much of the twentieth century, in recent years sociologists have started to re-engage with these topics in a variety of promising ways. It is our aim with this collection of about twenty peer-reviewed articles to exhibit the variety of approaches sociologists engage with, often in interdisciplinary collaborations. The special issue spans topics like biosociology, cultural evolution, evolutionary sociology, neurosociology, and sociogenomics. Works in all of these areas, for which we were able to win some of the experts in the respective fields, shows how biological, cultural, and social mechanisms interact in manifold and complex ways. With this exhibit of biosocial and evolutionary approaches in sociology we wish to inspire more sociologists to jump on board a much-needed interdisciplinary endeavor.

Als Teilprozess der Alterung und Schrumpfung der Bevölkerung ist die zunehmende Kinderlosigkeit i... more Als Teilprozess der Alterung und Schrumpfung der Bevölkerung ist die zunehmende Kinderlosigkeit in Deutschland in den letzten Jahren vor allem in Bezug auf ihre gesamtgesellschaftlichen Folgen diskutiert worden. Dabei geht es etwa um die Finanzierung des Rentensystems, die Gestaltung des Bildungswesens, Auswirkungen auf Arbeitsmarkt und Konsum, sowie Möglichkeiten durch eine familienfreundlichere Politik gegenzusteuern. Weniger Beachtung findet in der öffentlichen Diskussion hingegen die persönliche Situation der Kinderlosen selbst. In dieser Arbeit wird daher untersucht, inwiefern sich die sozialen Netzwerke Kinderloser und Eltern unterscheiden. Kompensieren Kinderlose das Fehlen von Kindern als Unterstützungspersonen durch andere Kontakte? Oder sind sie im Alter einsamer und häufiger auf formale Hilfsangebote angewiesen als Eltern? Und wie sind Kinderlose selbst als Helfer in ihren sozialen Netzwerken eingebunden? Diese und weitere Fragen sind nach wie vor von hoher sozialpolitischer Relevanz und werden in dieser 2002 erstellten Arbeit mit für die deutsche Wohnbevölkerung repräsentativen Daten des deutschen Alterssurvey eingehend untersucht.

"Small-world research started about fifty years ago with an idea about a social phenomenon: that ... more "Small-world research started about fifty years ago with an idea about a social phenomenon: that any two randomly chosen individuals in a country, or in the world even, could be connected with each other via a relatively short chain of acquaintances. But since its formation, this idea has evolved and – despite research almost dying off in the 1980s – has now become an exciting and vital area of study. Following the publication of seminal research in the late 1990s, which shed new light on the question of how short connections are possible in large scale networks, researchers began to see the significance of their subject reflected in many different facets of existence; small-world structures were found in a number of distinct contexts, including, for example, a protein interaction network and in communication networks via instant messaging. What had once started as small-world research has now evolved into an interdisciplinary science of complex networks.

In this four-volume set, the history, development and potential future of this intriguing idea is mapped and illustrated through a masterfully selected collection of articles, written and introduced by respected authorities on the subject."

Chapters in edited volumes by Sebastian Schnettler

Starke Vorbehalte gegenüber biologischen Erklärungsansätzen in der Soziologie und Kriminologie ha... more Starke Vorbehalte gegenüber biologischen Erklärungsansätzen in der Soziologie und Kriminologie haben lange eine integrierte Auseinandersetzung mit den Phänomenen Aggression und Gewalt (A/G) verhindert. Es gibt eine Vielzahl biologischer und sozialwissenschaftlicher Erklärungsansätze, die aus diesem Grund bisher eher nebeneinander existieren statt miteinander integriert zu sein. Diese Ansätze werden im folgenden Beitrag kurz vorgestellt. Auf der Seite biologischer Erklärungen geht es
dabei um proximate Ursachen für A/G, d.h. die zugrundeliegenden hormonellen, neurophysiologischen, genetischen und epigenetischen Prozesse. Und es geht um die ultimate Kausalität, d.h. die Frage nach der möglichen evolutionären Funktionalität von A/G. Auf der sozialwissenschaftlichen Seite geht es zum einen um große gesellschaftliche Fragen wie die Existenz sozialer Ordnung und die historische und gesellschaftsübergreifende Variation in der Prävalenz von A/G. Und es geht, ähnlich wie bei den biologischen Ansätzen, um die individuelle Variation von A/G,
hier allerdings begründet im sozialen Kontext, in den das Individuum eingebettet ist. Insgesamt gibt es zahlreiche Anzeichen dafür, dass biologische, soziale und kulturelle Mechanismen A/G kodeterminieren, jedoch fehlt es bislang an einer systematischen theoretischen Integration dieser
Mechanismen. Wir plädieren daher abschließend für eine stärkere Kommunikation beider Lager, um deren theoretische Vielfalt im Detail auf Kompatibilität hin zu überprüfen und neue integrierte Hypothesen für die empirische Arbeit abzuleiten.

Vielfalt und Zusammenhalt: Verhandlungen des 36. Kongresses der Deutschen Gesellschaft für Soziologie in Bochum 2012, 2014

Small World Research, 2013

… Expansion in Europe and the US. …, Jan 1, 2008

Research Reports & Working Papers by Sebastian Schnettler

This paper presents some preliminary findings from Wave 7 of the Innovation Panel (IP... more This paper presents some preliminary findings from Wave 7 of the Innovation Panel (IP7) of Understanding Society: The UK Household Longitudinal Study. Understanding Society is a major panel survey in the UK. In June 2014, the seventh wave of the Innovation Panel went into the field. IP7 includes a new refreshment sample and used a mixed-mode design, using on-line interviews and face-to-face interviews. This paper describes the design of IP7, the experiments carried and the preliminary findings from early analysis of the data.

Working Paper, May 2013

The economic stress hypothesis (ESH) suggests that economic decline leads to a decrease in the pr... more The economic stress hypothesis (ESH) suggests that economic decline leads to a decrease in the proportion of males born in a population. A multitude of additional influences on sex ratios that often cannot be accounted for empirically make assessing the validity of the ESH difficult. Thus, as a historical quasi-experiment, German reunification constitutes an interesting test case. The economy in East Germany, but not in West Germany, underwent a rapid decline in 1991. In the same year, the sex ratio decreased in East Germany, but not in West Germany. Catalano (2003) interpreted these developments as evidence in support of the ESH. Using more recent and detailed data, we re-examine this case to test an alternative explanation, the random variation hypothesis (RVH). Using aggregate data on sex ratios between 1946-2010 and individual-level data on over 13 million births from the German Birth Registry between 1991-2009, we find evidence supporting the RVH but not the ESH. First, the sex ratio in East Germany shows stronger deviations from the time trend in several years, and is seemingly unrelated to economic developments. The degree of variation is associated with the smaller and decreasing number of births in East Germany during the fertility decline following reunification. The individual-level analysis confirms that the 1991 decrease in the East German sex ratio could also be the result of random variation. A specificity of the East German transformation is the buffering of the consequences of economic decline through integration into the West German welfare state. Therefore, the ESH may be applicable in other transformation cases.

Objectives: This study examines if there exists a positive association between socioeconomic stat... more Objectives: This study examines if there exists a positive association between socioeconomic status and the proportion of male births in humans, as proposed by Trivers and Willard in 1973, using individual-level data drawn from the complete population of Sweden.

Methods: We examine more than 3,000,000 births between 1960 and 2007 using administrative register data with comprehensive information on various dimensions of socioeconomic status. We use six different operationalizations of socioeconomic status, including earnings, post-transfer income (including government allowances), wealth, parental wealth, educational level, and occupational class. We apply regression models that compare both changes in status for the same woman over time and differences in status across different women. We also measure socioeconomic status both at the year of child birth and the year of conception.

Results: Our results show the absence of any relationship between socioeconomic status and sex ratios, using a large number of different operationalizations of status.

Conclusions: We conclude that no substantive relationship between socioeconomic status and sex ratios exists for the population and period of our study.

Given increases in childlessness, we ask if and how the permanently childless substitute for adul... more Given increases in childlessness, we ask if and how the permanently childless substitute for adult children in their later-life support networks. Previous research finds that they are disadvantaged on several network and support indicators. Yet, the role of different substitution mechanisms remains unclear. We examine two substitution mechanisms: substitution through adjustments of network size/composition and through higher efficiency of personal ties. Data are from the German Ageing Survey (childless: N = 1,886; parents without/with residentially proximate children: N = 4,437/8,337). Our descriptive and regression results on network size/composition and the number of potential informational and emotional supporters show that both mechanisms play a role: the childless have more friends and extended kin, and they are more likely to consider them as potential supporters, than parents. Across cohorts or age groups, the relative effect size of network size/composition versus tie efficiency changes. Parents with no children nearby constitute a mixed type that shows similarities to the childless on some indicators of social support and to parents with at least one child nearby on other indicators. Our findings provide a foundation for better predicting how current demographic trends affect future scenarios of social support in later life and for identifying the future need for formal care services. Thus, they are relevant for social scientists and policy makers alike.

Environmental Health, Dec 2014

Background: The economic stress hypothesis (ESH) predicts decreases in the sex ratio at birth (SR... more Background: The economic stress hypothesis (ESH) predicts decreases in the sex ratio at birth (SRB) following economic decline. However, as many factors influence the SRB, this hypothesis is difficult to test empirically. Thus, researchers make use of quasi-experiments such as German reunification: The economy in East, but not in West Germany, underwent a rapid decline in 1991. A co-occurrence of a decline in the East German SRB in 1991 has been interpreted by some as support for the ESH. However, another explanation might be that the low SRB in 1991 stems from increased random variation in the East German SRB due to a drastically reduced number of births during the crisis. We look into this alternative random variation hypothesis (RVH) by re-examining the German case with more detailed data.

Methods: Our analysis has two parts. First, using aggregate-level birth register data for all births in the period between 1946 and 2011, we plot the quantum and variance of the SRB and the number of births and unemployment rates, separately for East and West Germany, and conduct a time series analysis on the East German SRB over time. Second, we model the odds for a male birth at the individual level in a multiple logistic regression (1991–2010, ~13.9 million births). Explanatory variables are related to the level of the individual birth, the mother of the child born, and the regional economic context.

Results: The aggregate-level analysis reveals a higher degree of variation of the SRB in East Germany. Deviations from the time trend occur in several years, seemingly unrelated to economic development, and the deviation in 1991 is not statistically significant. The individual-level analysis confirms that the 1991-drop in the East German SRB cannot directly be attributed to economic development and that there is no statistically significant effect of economic development on sex determination in East or West Germany.

Conclusion: Outcomes support the RVH but not the ESH. Furthermore, our results speak against a statistically significant effect of the reunification event itself on the East German SRB. We discuss the relative importance of behavioral and physiological responses to macro-level stressors, a distinction that may help integrate previously mixed findings.

Vor dem Hintergrund des demographischen Ungleichgewichts von Männern und Frauen in Asien beschäft... more Vor dem Hintergrund des demographischen Ungleichgewichts von Männern und Frauen in Asien beschäftigen sich diverse Autoren mit möglichen Konsequenzen eines Frauen- oder Männermangels, unter anderem für die Gewaltinzidenz in den betroffenen Gesellschaften oder Regionen. Allerdings präsentieren sich die bisherigen theoretischen Ansätze wie auch die empirische Evidenz als uneinheitlich. Der Beitrag gibt einen Überblick über sozialwissenschaftliche und evolutionstheoretische Perspektiven auf die Fragestellung und versucht diese zu integrieren. Darüber hinaus werden empirische Befunde dargestellt und eingeordnet sowie eigene Projekte vorgestellt und Forschungsdesiderata formuliert.

PLoS ONE, Feb 22, 2013

Based on evolutionary theory, Trivers & Willard (TW) predicted the existence of mechanisms that l... more Based on evolutionary theory, Trivers & Willard (TW) predicted the existence of mechanisms that lead parents with high levels of resources to bias offspring sex composition to favor sons and parents with low levels of resources to favor daughters. This hypothesis has been tested in samples of wealthy individuals but with mixed results. Here, I argue that both sample selection due to a high number of missing cases and a lacking specification of the timing of wealth accumulation contribute to this equivocal pattern. This study improves on both issues: First, analyses are based on a data set of U.S. billionaires with near-complete information on the sex of offspring. Second, subgroups of billionaires are distinguished according to the timing when they acquired their wealth. Informed by recent insights on the timing of a potential TW effect in animal studies, I state two hypotheses. First, billionaires have a higher share of male offspring than the general population. Second, this effect is larger for heirs and heiresses who are wealthy at the time of conception of all of their children than for self-made billionaires who acquired their wealth during their adult lives, that is, after some or all of their children have already been conceived. Results do not support the first hypothesis for all subgroups of billionaires. But for males, results are weakly consistent with the second hypothesis: Heirs but not self-made billionaires have a higher share of male offspring than the U.S. population. Heiresses, on the other hand, have a much lower share of male offspring than the U.S. average. This hints to a possible interplay of at least two mechanisms affecting sex composition. Implications for future research that would allow disentangling the distinct mechanisms are discussed.

Journal of Biosocial Science, Sep 2013

Based on evolutionary reasoning, Trivers & Willard (1973) predicted status-biased sex composition... more Based on evolutionary reasoning, Trivers & Willard (1973) predicted status-biased sex composition and parental investment with son-preferencing effects in higher, and daughter-preferencing effects in lower status groups. Previous research shows mixed results. This study uses event-history methods and Swedish register data to study one possible mechanism in isolation: do parents in different status groups vary in their proclivities to continue fertility based on the sex composition of previous offspring? The results show no support for the Trivers–Willard hypothesis on a wide range of different status indicators. Future research on the stated hypothesis should focus on physiological rather than behavioural mechanisms.

Journal of Family Research (Zeitschrift für Familienforschung), 2011

Consistent with inclusive fitness theory, evolutionary biologists predict that individuals care m... more Consistent with inclusive fitness theory, evolutionary biologists predict that individuals care more for their biological than their social children and hence that biological children assess the relationships to their parents better than stepchildren. To test this assumption, we use data from the U.S. National Longitudinal Study of Adolescent Health (Add Health). Unlike many other studies
that have been conducted so far, this survey allows us to analyze the consequences of the dynamic between social and biological parent-child relationships within the same families. We use
comparisons of sibling pairs and fixed-effects regression to achieve the within-family comparison. Both the descriptive and multivariate regression results confirm that – even after controlling for other relevant influences – biological parenthood
matters with regard to children’s relationship assessments (perceived parental care and closeness of the parent-child relationship) and in both the relationships to resident fathers and mothers. In the discussion, we comment on the possible inte-
gration of the evolutionary and sociological perspectives and close with some recommendations for future data collection that could allow researchers to analyze the relative impact of biological and social influences on parent-child relationships on a more fine-grained level.

Social Networks, 2009

Small-world studies were introduced by Milgram and others in the 1960s and 1970s. These studies, ... more Small-world studies were introduced by Milgram and others in the 1960s and 1970s. These studies, and a majority of variants conducted by others, display a number of methodological weaknesses that bias their results. While no explicit methodological standard exists for these studies, here I derive a number of best-practice criteria for small-world studies by pointing out mistakes of previous studies, and by applying methodological standards from other empirical research areas. Improving the methodology of letter referral studies is important, because such studies could still be useful in a number of contexts today, especially for the exploration of factors affecting targeted search processes.

Social Networks, 2009

This paper offers a structured overview of 50 years of small-world research. Initially formulated... more This paper offers a structured overview of 50 years of small-world research. Initially formulated by Pool and Kochen in the mid-1950s, the small-world concept can be divided into six research foci, based on three dimensions (structural, process-related, psychological), and two process-related themes (diffusion, search). Building on this analytical distinction, the article provides a historical summary of the different phases of research on the small-world problem, and summarizes the empirical and theoretical progress on different facets of the small-world phenomenon. The paper concludes with a brief assessment of accomplishments and open questions, suggesting some possible future research areas.

Special Issue 64, Kölner Zeitschrift für Soziologie und Sozialpsychologie, 2024

After a long neglect of biosocial and evolutionary approaches to human behavior and sociality in ... more After a long neglect of biosocial and evolutionary approaches to human behavior and sociality in sociology during much of the twentieth century, in recent years sociologists have started to re-engage with these topics in a variety of promising ways. It is our aim with this collection of about twenty peer-reviewed articles to exhibit the variety of approaches sociologists engage with, often in interdisciplinary collaborations. The special issue spans topics like biosociology, cultural evolution, evolutionary sociology, neurosociology, and sociogenomics. Works in all of these areas, for which we were able to win some of the experts in the respective fields, shows how biological, cultural, and social mechanisms interact in manifold and complex ways. With this exhibit of biosocial and evolutionary approaches in sociology we wish to inspire more sociologists to jump on board a much-needed interdisciplinary endeavor.

Als Teilprozess der Alterung und Schrumpfung der Bevölkerung ist die zunehmende Kinderlosigkeit i... more Als Teilprozess der Alterung und Schrumpfung der Bevölkerung ist die zunehmende Kinderlosigkeit in Deutschland in den letzten Jahren vor allem in Bezug auf ihre gesamtgesellschaftlichen Folgen diskutiert worden. Dabei geht es etwa um die Finanzierung des Rentensystems, die Gestaltung des Bildungswesens, Auswirkungen auf Arbeitsmarkt und Konsum, sowie Möglichkeiten durch eine familienfreundlichere Politik gegenzusteuern. Weniger Beachtung findet in der öffentlichen Diskussion hingegen die persönliche Situation der Kinderlosen selbst. In dieser Arbeit wird daher untersucht, inwiefern sich die sozialen Netzwerke Kinderloser und Eltern unterscheiden. Kompensieren Kinderlose das Fehlen von Kindern als Unterstützungspersonen durch andere Kontakte? Oder sind sie im Alter einsamer und häufiger auf formale Hilfsangebote angewiesen als Eltern? Und wie sind Kinderlose selbst als Helfer in ihren sozialen Netzwerken eingebunden? Diese und weitere Fragen sind nach wie vor von hoher sozialpolitischer Relevanz und werden in dieser 2002 erstellten Arbeit mit für die deutsche Wohnbevölkerung repräsentativen Daten des deutschen Alterssurvey eingehend untersucht.

"Small-world research started about fifty years ago with an idea about a social phenomenon: that ... more "Small-world research started about fifty years ago with an idea about a social phenomenon: that any two randomly chosen individuals in a country, or in the world even, could be connected with each other via a relatively short chain of acquaintances. But since its formation, this idea has evolved and – despite research almost dying off in the 1980s – has now become an exciting and vital area of study. Following the publication of seminal research in the late 1990s, which shed new light on the question of how short connections are possible in large scale networks, researchers began to see the significance of their subject reflected in many different facets of existence; small-world structures were found in a number of distinct contexts, including, for example, a protein interaction network and in communication networks via instant messaging. What had once started as small-world research has now evolved into an interdisciplinary science of complex networks.

In this four-volume set, the history, development and potential future of this intriguing idea is mapped and illustrated through a masterfully selected collection of articles, written and introduced by respected authorities on the subject."

Starke Vorbehalte gegenüber biologischen Erklärungsansätzen in der Soziologie und Kriminologie ha... more Starke Vorbehalte gegenüber biologischen Erklärungsansätzen in der Soziologie und Kriminologie haben lange eine integrierte Auseinandersetzung mit den Phänomenen Aggression und Gewalt (A/G) verhindert. Es gibt eine Vielzahl biologischer und sozialwissenschaftlicher Erklärungsansätze, die aus diesem Grund bisher eher nebeneinander existieren statt miteinander integriert zu sein. Diese Ansätze werden im folgenden Beitrag kurz vorgestellt. Auf der Seite biologischer Erklärungen geht es
dabei um proximate Ursachen für A/G, d.h. die zugrundeliegenden hormonellen, neurophysiologischen, genetischen und epigenetischen Prozesse. Und es geht um die ultimate Kausalität, d.h. die Frage nach der möglichen evolutionären Funktionalität von A/G. Auf der sozialwissenschaftlichen Seite geht es zum einen um große gesellschaftliche Fragen wie die Existenz sozialer Ordnung und die historische und gesellschaftsübergreifende Variation in der Prävalenz von A/G. Und es geht, ähnlich wie bei den biologischen Ansätzen, um die individuelle Variation von A/G,
hier allerdings begründet im sozialen Kontext, in den das Individuum eingebettet ist. Insgesamt gibt es zahlreiche Anzeichen dafür, dass biologische, soziale und kulturelle Mechanismen A/G kodeterminieren, jedoch fehlt es bislang an einer systematischen theoretischen Integration dieser
Mechanismen. Wir plädieren daher abschließend für eine stärkere Kommunikation beider Lager, um deren theoretische Vielfalt im Detail auf Kompatibilität hin zu überprüfen und neue integrierte Hypothesen für die empirische Arbeit abzuleiten.

Vielfalt und Zusammenhalt: Verhandlungen des 36. Kongresses der Deutschen Gesellschaft für Soziologie in Bochum 2012, 2014

Small World Research, 2013

… Expansion in Europe and the US. …, Jan 1, 2008

This paper presents some preliminary findings from Wave 7 of the Innovation Panel (IP... more This paper presents some preliminary findings from Wave 7 of the Innovation Panel (IP7) of Understanding Society: The UK Household Longitudinal Study. Understanding Society is a major panel survey in the UK. In June 2014, the seventh wave of the Innovation Panel went into the field. IP7 includes a new refreshment sample and used a mixed-mode design, using on-line interviews and face-to-face interviews. This paper describes the design of IP7, the experiments carried and the preliminary findings from early analysis of the data.

Working Paper, May 2013

The economic stress hypothesis (ESH) suggests that economic decline leads to a decrease in the pr... more The economic stress hypothesis (ESH) suggests that economic decline leads to a decrease in the proportion of males born in a population. A multitude of additional influences on sex ratios that often cannot be accounted for empirically make assessing the validity of the ESH difficult. Thus, as a historical quasi-experiment, German reunification constitutes an interesting test case. The economy in East Germany, but not in West Germany, underwent a rapid decline in 1991. In the same year, the sex ratio decreased in East Germany, but not in West Germany. Catalano (2003) interpreted these developments as evidence in support of the ESH. Using more recent and detailed data, we re-examine this case to test an alternative explanation, the random variation hypothesis (RVH). Using aggregate data on sex ratios between 1946-2010 and individual-level data on over 13 million births from the German Birth Registry between 1991-2009, we find evidence supporting the RVH but not the ESH. First, the sex ratio in East Germany shows stronger deviations from the time trend in several years, and is seemingly unrelated to economic developments. The degree of variation is associated with the smaller and decreasing number of births in East Germany during the fertility decline following reunification. The individual-level analysis confirms that the 1991 decrease in the East German sex ratio could also be the result of random variation. A specificity of the East German transformation is the buffering of the consequences of economic decline through integration into the West German welfare state. Therefore, the ESH may be applicable in other transformation cases.

Based on evolutionary reasoning, Trivers and Willard (1973) predict status-biased sex composition... more Based on evolutionary reasoning, Trivers and Willard (1973) predict status-biased sex composition and parental investment with son-preferencing effects in higher, and daughter-preferencing effects in lower status groups. Previous research shows mixed results. Using event-history methods and Swedish register data, we study one possible mechanism in isolation: Do parents in different status groups vary in their proclivities to continue fertility based on the sex composition of previous offspring? Results show no support for the Trivers-Willard hypothesis on a wide range of different status indicators. We recommend that future research on the stated hypothesis focuses on physiological rather than behavioral mechanisms.

Problemhintergrund des Projektes Die Entwicklung der Region Bodensee wird von einer Viel... more Problemhintergrund des Projektes
Die Entwicklung der Region Bodensee wird von einer Vielfalt an Akteuren, Institutionen und Strategien geleitet. Diesen ist gemeinsam, dass sie vorwiegend kurz‐ bis mittelfristige Planungshorizonte verfolgen und in arbeitsteiligen Politikfeldern gefangen sind. Doch die langfristigen Trends wie demografischer Wandel, Klimaveränderung und andere machen vor der Region Bodensee nicht Halt. Um für deren Einflüsse auf die Entwicklung der Region langfristig gerüstet zu sein, hat das Projekt "Bodensee 2030“ eine regionale Foresight‐Studie zum Ziel.

Zielsetzung des Projektes
Breit getragene, gemeinsame Zukunftsbilder sollen die strategische Intelligenz in der Region verbessern und eine grössere Kohärenz in den laufenden Entscheidungen bewirken. Der thematische Fokus liegt auf der Sicherstellung einer innovativen Wirtschaftsentwicklung. Hierfür werden mit einem breiten Partizipationsansatz die relevanten Entwicklungstrends identifiziert, in ihrer Bedeutung für die
Region diskutiert sowie durch Ableitung konkreter Handlungsempfehlungen für die Region bearbeitbar gemacht.

KZfSS Kölner Zeitschrift für Soziologie und Sozialpsychologie

Based on evolutionary theory, Trivers & Willard (TW) predicted the existence of mechanisms that l... more Based on evolutionary theory, Trivers & Willard (TW) predicted the existence of mechanisms that lead parents with high levels of resources to bias offspring sex composition to favor sons and parents with low levels of resources to favor daughters. This hypothesis has been tested in samples of wealthy individuals but with mixed results. Here, I argue that both sample selection due to a high number of missing cases and a lacking specification of the timing of wealth accumulation contribute to this equivocal pattern. This study improves on both issues: First, analyses are based on a data set of U.S. billionaires with near-complete information on the sex of offspring. Second, subgroups of billionaires are distinguished according to the timing when they acquired their wealth. Informed by recent insights on the timing of a potential TW effect in animal studies, I state two hypotheses. First, billionaires have a higher share of male offspring than the general population. Second, this effec...

Encyclopedia of Evolutionary Psychological Science

Zeitschrift Fur Familienforschung, 2011

Consistent with inclusive fitness theory, evolutionary biologists predict that individuals care m... more Consistent with inclusive fitness theory, evolutionary biologists predict that individuals care more for their biological than their social children and hence that biological children assess the relationships to their parents better than stepchildren. To test this assumption, we use data from the U.S. National Longitudinal Study of Adolescent Health (Add Health). Unlike many other studies that have been conducted so far, this survey allows us to analyze the consequences of the dynamic between social and biological parent-child relationships within the same families. We use comparisons of sibling pairs and fixed-effects regression to achieve the within-family comparison. Both the descriptive and multivariate regression results confirm that – even after controlling for other relevant influences – biological parenthood matters with regard to children’s relationship assessments (perceived parental care and closeness of the parent-child relationship) and in both the relationships to resi...

Encyclopedia of Evolutionary Psychological Science

Abstract: In this dissertation, I test the Trivers-Willard hypothesis of differential parental in... more Abstract: In this dissertation, I test the Trivers-Willard hypothesis of differential parental investment using the genetic sample of the US National Longitudinal Study of Adolescent Health. Based on general propositions of evolutionary theory, Trivers and Willard ...

Die Signifikanz des hier zu besprechenden Artikels ist im Kontext der sogenannten » Small-World F... more Die Signifikanz des hier zu besprechenden Artikels ist im Kontext der sogenannten » Small-World Forschung « und Forschung zu komplexen Netzwerken zu bewerten. Ausgehend von der Anekdote zweier Fremder, die sich irgendwo in der Welt treffen und uberrascht feststellen, dass sie eine gemeinsame Bekannte haben – » It’s a small world! « – fragte man sich Mitte des 20. Jahrhunderts, wie Netzwerke strukturiert sind, um dieses intuitiv uberraschende Ereignis sowie dessen Erweiterung um indirekte Verbindungen uber zwei, drei oder mehr Bekanntschaftsgrade moglich zu machen. Trotz diverser methodischer Ansatze, einzelne Parameter der Netzwerkstruktur zu schatzen – darunter Gedankenexperimente, mathematische Modellierungen, Tagebuchstudien und Milgrams Briefexperiment (Milgram → 1967) – lies sich zunachst keine zufriedenstellende Losung des Problems finden, so dass die Forschung in dem Bereich in den 1980er Jahren fast zu einem Stillstand gekommen war (Schnettler 2013).

Encyclopedia of Evolutionary Psychological Science, 2019

Als Teilprozess der Alterung und Schrumpfung der Bevolkerung ist die zunehmende Kinderlosigkeit i... more Als Teilprozess der Alterung und Schrumpfung der Bevolkerung ist die zunehmende Kinderlosigkeit in Deutschland in den letzten Jahren vor allem in Bezug auf ihre gesamtgesellschaftlichen Folgen diskutiert worden. Dabei geht es etwa um die Finanzierung des Rentensystems, die Gestaltung des Bildungswesens, Auswirkungen auf Arbeitsmarkt und Konsum, sowie Moglichkeiten durch eine familienfreundlichere Politik gegenzusteuern. Weniger Beachtung findet in der offentlichen Diskussion hingegen die personliche Situation der Kinderlosen selbst. In dieser Arbeit wird daher untersucht, inwiefern sich die sozialen Netzwerke Kinderloser und Eltern unterscheiden. Kompensieren Kinderlose das Fehlen von Kindern als Unterstutzungspersonen durch andere Kontakte? Oder sind sie im Alter einsamer und haufiger auf formale Hilfsangebote angewiesen als Eltern? Und wie sind Kinderlose selbst als Helfer in ihren sozialen Netzwerken eingebunden? Diese und weitere Fragen sind nach wie vor von hoher sozialpolitisc...

Im Fokus des Kapitels liegen die politischen, okonomischen und gesamtgesellschaftlichen Wechselwi... more Im Fokus des Kapitels liegen die politischen, okonomischen und gesamtgesellschaftlichen Wechselwirkungen zwischen Bevolkerungsentwicklung und Arbeitsmarkt. Zunachst geben die Autoren einen Uberblick uber demografische Entwicklungen in Deutschland und Europa in den letzten Jahrzehnten, um Arbeitsmarktentwicklungen in die gesamtdemografische Lage einzuordnen. Anschliesend beschreiben sie den Zusammenhang von Bevolkerungsentwicklung und Arbeitskraftepotenzial anhand verschiedener theoretischer Erklarungsansatze und empirischer Befunde. Sie schliesen das Kapitel mit einem Fazit und einem Verweis auf offene Forschungsfragen ab.

level, a mathematically precise definition of what constitutes a small-world network is logarithm... more level, a mathematically precise definition of what constitutes a small-world network is logarithmic scaling of the average geodesic in a network. That is, a network is considered “small” if the average geodesic grows logarithmically with increasing network size (Newman, 2003: 183). Furthermore, in recent years attempts have been made at quantifying “small-world-ness” as a continuous property, thereby giving guidance to researchers as to the relative size of small-world properties for a given network (Humphries and Gurney, 2008; Uzzi and Spiro, 2005). When calculating the degree of small-world-ness, one needs to carefully choose the correct version of a random network for comparison with the network of interest; for instance, the degree of small-world-ness in a bipartite network requires comparison to a random bipartite network (see Uzzi et al., 2007: 85). Besides probing real networks for characteristics derived from formal network models, researchers have also studied the structura...

Encyclopedia of Evolutionary Psychological Science

Evolution and Human Behavior

... Im dritten Teil meiner Arbeit greife ich die Frage nach der sozialen Rele-vanz des Phänomens ... more ... Im dritten Teil meiner Arbeit greife ich die Frage nach der sozialen Rele-vanz des Phänomens auf und werde dabei eine konzeptionelle Kritik an der SW-Forschung skizzieren, aus der sich Empfehlungen für zukünftige Forschung in diesem Bereich ableiten lassen. ...

Ad-hoc-Session "Evolutionäre Soziologie: Zur Interaktion biologischer, sozialer und kultureller E... more Ad-hoc-Session "Evolutionäre Soziologie: Zur Interaktion biologischer, sozialer und kultureller Einflüsse auf menschliches Verhalten". Gemeinsamer Kongress der Deutschen (DGS) und Österreichischen (ÖGS) Gesellschaft für Soziologie, 23.-25. August 2021, Wien (Österreich).

Wir erbitten die Einreichung eines Abstracts (max. 2.400 Zeichen – exkl. Titel – inkl. Leerzeichen) bis zum 15. April 2021 an die OrganisatorInnen der Ad-hoc-Gruppe.

Link zur Website des DGS / ÖGS Kongresses: https://kongress2021.soziologie.de