The environment is a common space where the “swarm” evolves through interactions among it’s members. The environment allows to share the ”’same reality”’ for all of them, that is, when a member modifies the ”reality” in some way, the others see the same facts.
This sentence may seem obvious baring in mind certain examples from nature such as bees or ant colonies, but it definitely makes more sense in computer simulations where nature can’t help us and so we must ensure that our artificial environments provide the same unity: an ant, for instance, takes a ”larva” from the ground and it’s no longer available for a another ant with the same intention.
The environment must provide the foundations for communication among swarm members, for instance, the termites use some pheromones that attach to the environment while at the same time an evaporation process slowly removes them. The concentration of these pheromones guides other termites to stack the material for the pillars that continue to grow, while gradually the pillar’s ends approach each other, forming a closed “arc”.