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.

Non-imprinted genes can contribute to parent-of-origin effects on phenotype through interactions with imprinted genes.

By considering a new form of social cheat strategy, arms-races-like dynamics between coevolving selfish traits could emerge from the tragedy of the commons and help explain the variations in cheating levels observed in many microbes and eusocial insects.

A description of evolution that is based on birth-death processes, and in which fitness is at most a derived quantity, is advocated.

Whereas partner-serving phenotype is intuitively quantified as benefit release rate, molecular genetics revealed an example where this thinking fails, motivating a more general metric.

Building on previous work (Momeni et al., 2013), it is shown that recognizing the hierarchical organization of biological systems resolves the ongoing controversy on pro-cooperation mechanisms.

A new model describes evolutionary transitions in individuality in terms of tradeoff and tradeoff-breaking events as opposed to changes in the nature of fitness.

Experiments show that pathogens spread more easily among relatives causing increased mortality, but such costs are cancelled out by the benefits of living with kin when pathogens are rare.

Hybridization not only generates genetic diversity, but this diversity can alter the shape of the fitness landscape, changing which genotypic combinations are favored by natural selection and which accessible genotypic paths lead to novel fitness peaks.