Hamilton's rule can be violated when costs and benefits of cooperation are defined using the counterfactual method, and when they depend on the cooperation of others.

The zebrafish is a premier model organism for biomedical research, with a rich array of tools and genomic resources, and combining these with a fuller appreciation of wild zebrafish ecology could greatly extend its utility in biological research.

Shearing in fluid flow induces or enhances budding dispersal in microbial populations, resulting in stronger cooperative behavior.

A mathematical model built around the assumption that the desire to maintain internal homeostasis drives the behavior of animals, by affecting their learning processes, can explain many real-world behaviors, including some that might otherwise appear irrational.