What determines our views on taxation and crime, healthcare and religion, welfare and gender roles? And why do opinions about these seemingly disparate aspects of our social lives coalesce the way they do? Research over the last 50 years has suggested that political attitudes and values around the globe are shaped by two ideological dimensions, often referred to as economic and social conservatism. However, it remains unclear why this ideological structure exists. Here, we highlight the striking concordance between these two dimensions of ideology and two key aspects of human sociality: cooperation and group conformity. Humans cooperate to a greater degree than our great ape relatives, paying personal costs to benefit others. Humans also conform to group-wide social norms and punish norm violators in interdependent, culturally marked groups. Together, these two shifts in sociality are posited to have driven the emergence of large-scale complex human societies. We argue that fitness trade-offs and behavioural plasticity have maintained strategic individual differences in both cooperation and group conformity, naturally giving rise to the two dimensions of political ideology. Supported by evidence from psychology, behavioural genetics, behavioural economics, and primatology, this evolutionary framework promises novel insight into the biological and cultural basis of political ideology.

1What determines our views on taxation and crime, healthcare and religion, welfare and 2 gender roles? And why do opinions about these seemingly disparate aspects of our social 3 lives coalesce the way they do? Research over the last 50 years has suggested that political 4 attitudes and values around the globe are shaped by two ideological dimensions, often 5 referred to as economic and social conservatism. However, it remains unclear why this 6 ideological structure exists. Here, we highlight the striking concordance between these two 7 dimensions of ideology and two key aspects of human sociality: cooperation and group 8 conformity. Humans cooperate to a greater degree than our great ape relatives, paying 9 personal costs to benefit others. Humans also conform to group-wide social norms and punish 10 norm violators in interdependent, culturally marked groups. Together, these two shifts in 11 sociality are posited to have driven the emergence of large-scale complex human societies. 12 We argue that fitness trade-offs and behavioural plasticity have maintained strategic 13 individual differences in both cooperation and group conformity, naturally giving rise to the 14 two dimensions of political ideology. Supported by evidence from psychology, behavioural 15 genetics, behavioural economics, and primatology, this evolutionary framework promises 16 novel insight into the biological and cultural basis of political ideology. 17 18

Cross-national analyses test hypotheses about the drivers of global variation in national outcomes. However, since nations are connected in various ways, such as via spatial proximity and shared cultural ancestry, cross-national analyses often violate assumptions of non-independence, inflating false positive rates. Here, we show that, despite being recognised as an important statistical pitfall for over 200 years, cross-national research in economics and psychology still does not sufficiently account for non-independence. In a review of the 100 highest-cited cross-national studies of economic development and values, we find that controls for non-independence are rare. When studies do include controls for non-independence, our simulations suggest that commonly used methods continue to produce false positives. In reanalyses of twelve cross-national relationships, we show that half are no longer significant after controlling for non-independence using global proximity matrices. We urge social scientists to sufficiently control for non-independence in cross-national research.

Contagious yawning has been suggested to be a potential signal of empathy in non-human animals. However, few studies have been able to robustly test this claim. Here, we ran a Bayesian multilevel reanalysis of six studies of contagious yawning in dogs. This provided robust support for claims that contagious yawning is present in dogs, but found no evidence that dogs display either a familiarity or gender bias in contagious yawning, two predictions made by the contagious yawning–empathy hypothesis. Furthermore, in an experiment testing the prosociality bias, a novel prediction of the contagious yawning–empathy hypothesis, dogs did not yawn more in response to a prosocial demonstrator than to an antisocial demonstrator. As such, these strands of evidence suggest that contagious yawning, although present in dogs, is not mediated by empathetic mechanisms. This calls into question claims that contagious yawning is a signal of empathy in mammals.

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