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.

Experimental manipulations of social groups of ostriches show that the benefits of cooperative parental care for females, and the costs of sexual competition for males, lead to sex differences in optimal group sizes.

Two cooperative populations of yeast cells that cannot distinguish between cooperative partners and cheating intruders can still self-organize into clusters that exclude cheaters.

The Marmoset Apparatus for Automated Pulling provides a powerful and scalable experimental platform for studying behavioral and neural mechanisms underlying cooperation in freely moving marmosets.

A population of pathogenic bacteria is found to respond to the loss of cooperation by privatising an essential function.

A systematic experimental comparison of prosocial behavior in eight corvid species reveals sex-specific effects of cooperative breeding and colonial nesting, thereby adding important new insights regarding the evolution of prosociality.

The frequent co-occurrence of two variants of influenza is due to the fact that they cooperate, meaning that a mixed population grows better than either variant alone.

Simulations and experiments on systems containing two different populations of microorganisms show that interactions that benefit at least one of the populations can lead to communities with stable compositions, and that strong cooperation between two populations can lead to communities in which both populations are mixed together.

Mutations that directly benefit both self and cooperative partner can readily evolve to promote cooperation.

By integrating theoretical and empirical approaches, the results show that linking abiotic factor and biotic interactions on the niche width will be critical for understanding species-specific responses to climate change.