Many aspects of human adaptation to changing environment remain unanswered, even if a substantial progress has been made towards a better understanding of populations evolution in recent years. This paper proposes an explanatory model of evolutionary adaptation that seems to account fairly well for certain qualitative dynamic patterns pointed out by geneticists. This model is characterised by the presence of feedback loops (in addition to feedforward channels that are certainly present, too). Although the importance of feedback in the evolution process is widely accepted today, no explicit representation of this phenomenon has been presented yet. This task is humbly undertaken from a control engineering perspective in this note which does not claim to be scientifically accurate, but simply to stimulate discussion among the experts in this delicate and manifold field. Specifically, the proposed model consists of four nested loops characterised by different time scales and embracing different spheres. On the basis of this simple model, some considerations on the system stability as well as on its transient and asymptotic behaviour are made.