This paper explores the following question: how a fixed-size population of autonomous agents (such as a swarm of robotic agents) may evolve altruistic behaviors during open-ended evolution. In particular, we focus on a situation where the tragedy of commons can possibly occur: a situation where individuals must display altruistic behaviors in order for the whole population to avoid extinction. Our approach considers a sub-individual framework, defined at the level of genomes rather than agents, in order to provide an efficient algorithmic solution for the emergent of coordination among the population. Experiments show that the proposed evolutionary adaptation algorithm favors the emergence of altruistic behavior under some assumptions regarding genome relatedness. In-depth experimental studies explore the relation between genotypic diversity and degree of altruism as well as the exact nature of the evolutionary adaptation process.