By far not an expert in this area, but if (when?) we successfully generate true intelligence, I suspect it will be through some sort of "ensemble" model, where multiple agents are trained in parallel and interact with each other. Intelligence as we know it hasn't just resulted from an evolution of one agent in response to a cost function, but rather through the complex interactions of agents (humans and organisms in general) over time. I feel like the underlying journal article (https://www.sciencedirect.com/science/article/pii/S000437022...) is missing discussion of this.