The neural crest generates a broad spectrum of cell types that migrate across the body plan to populate multiple tissues1. However, the relationship between lineages of neural crest derivatives remains unclear, and the extent to which neural crest cells delaminated from the neural tube have specified fates remains debated. Here, leveraging CRISPR barcoding in mice and mosaic variant barcode analysis in humans, we demonstrate robust bilateral progenitor clonal spread of neural crest progenitors along the rostrocaudal axis but limited clonal overlap between sensory and sympathetic lineages. Computational modelling of mosaic variants suggests that most neural crest cells show strong fate restriction before delamination. Real-time imaging of quail embryos further shows a fibroblast-growth-factor-dependent rostrocaudal dispersion of neural crest cells across multiple axial levels. These findings support a model in which neural crest fate bias predominantly emerges within the neural tube, with only a minor subset of delaminated progenitors retaining multipotency to generate both sensory and sympathetic derivatives.

Social organization and division of labour are fundamental to animal societies1-3, yet how these structures emerge from individual interactions and are shaped by neuromodulation remains unclear. Here, using behavioural tracking in a semi-natural environment, neural recordings and computational models that integrate reinforcement learning and social condition, we show that triads of isogenic mice develop specialized roles spontaneously while solving a foraging task under social constraints. Notably, despite minor intra-sex differences in behaviour when mice were tested alone, male triads formed stable worker-scrounger relationships driven by competition, whereas female triads adopted uniform, cooperative strategies. These sex-divergent roles were shaped by dopaminergic activity in the ventral tegmental area. Model analysis revealed how intra-sex and inter-sex parameter differences in resource exploitation, combined with contingent social interactions, drive behavioural specialization and division of labour. Most notably, it highlighted how contingency, amplified by competition, magnifies individual differences and shapes social profiles. The plastic, adaptive nature of social organization was apparent when sex mixing or reintroducing experienced individuals into naive groups reshaped role distribution. Furthermore, dopaminergic manipulations confirmed this plasticity, reshaping roles and altering group structure. Our findings support a multi-scale feedback loop whereby social context shapes neural states, which in turn reinforce behavioural specialization and stabilize social structures.

Science aspires to be cumulative. Reproducibility efforts strengthen science by testing the reliability of published findings, promoting self-correction, and informing policy-making1. Computational reproductions, whereby independent researchers reproduce the results of published studies, are an essential diagnostic tool2-10. Such efforts should have greater visibility11-16. However, little social science reproduction and robustness has been conducted at scale10,13,17-23. Here we reproduced original analyses and conducted robustness checks of 110 articles that were published in leading economics and political science journals with mandatory data and code sharing policies17,18. We found that more than 85% of published claims were computationally reproducible. In robustness checks, our reanalyses showed that 72% of statistically significant estimates remain significant and in the same direction, and the median reproduced effect size is nearly the same as the originally published effect size (that is, 99% of the published effect size). Additionally, 6 independent research teams examined 12 pre-specified hypotheses about determinants of robustness. Research teams with more experience found lower levels of robustness, and robustness did not correlate with author characteristics or data availability.