A high birth rate, and a high bar for keeping your nads til the end of puberty. By 11, you should be able to... a) solo a bear b) run a marathon c) perfectly memorize and recite a 52-card shuffle after thumbing through it once d) ace any calculus test e) have model-quality good looks f) be an expert musician, or g) idk, something about empathy and the ability to bring people together ...or any number of other exceptional, desirable aptitudes. Anyways, that's the fastest eugenics method, with geography divided amongst nobility who each pursue a particular eugenic ideal. You'd have to exclude genetically inferior men from breeding, so you can eliminate undesirable traits for a future Utopia. Traits that no one can quite agree on. You'll need self-destructing governments capable of self-improving by reconstituting themselves, based on criteria no one can quite agree on. In fact, that's an important missing piece. Whose Utopia are we talking about? Are we talking equal outcomes, equal opportunities, or natural law? Are we talking about absurd abundance and leisure, everyone having a meaningful struggle requiring personal excellence, or a life of devotion to our posterity and gratitude to our ancestry? The truth is only the latter can include all three.