KABLOW!!
And a new sci-fi scenario for your edification.

I got this idea from Michael Pollan's the Botany of Desire([link]), back before the summer. In his book, Pollan discusses apple-trees, which are capable of producing offspring from seed (called pippins) that grow into wildly different trees from their parents, and bear very different fruit. According to Pollan, plant breeders will grow pippins to maturity, select the trees that express the traits they want, then propagate that line by cloning. Trees grown from clones (called scions) of course end up more or less like the original.

Throw sentience into the mix and what happens? You'd get something with very flexible gross morphology (perhaps something like the swiss-army-urchin? [link] ha!). Shuffling genes with sex will produce pippin-children, which may or may not grow to express qualities their parents would approve of. Initially, of course, variable pippins would be very useful to spread the species across a variety of environments. However, as the population becomes established and intra-species competition becomes more intense, the chances that any single pippin will be an improvement on its parents rapidly decrease. High intelligence, usable hands, sanity, robust health, and so on, aren't easy to arrive at by random chance, and as a society becomes more advanced, the competitive bar keeps rising, and fewer and fewer pippins are capable of taking part in society (random variations are more likely to make them less competitive than more).

Fortunately, this species can also reproduce asexually, producing scion-children that are identical to their parents in ability, while the vast majority of sexually-produced pippins are virtually animals.

Clearly, different social institutions would evolve around this reproductive strategy. You might get:

Stratification, with different pippin-lines extended by scions into different castes with different abilities. Production of pippins is illegal, because they introduce uncertainty into the system.

Totalitarianism, where the state is responsible for the care of pippins. The government tests pippins for ability early on, and kills the vast majority of them. Citizens may apply for leave to produce scions, and the government can control the makeup of the population by controlling who gets permission to replicate.

Pippin-ranching. Individual families (either country nobility or homesteaders in newly opened territory) keep their own lands and make pippin-ranching part of the family business. Pippins are bred and traded like horses or game-cocks, and there are ritual requirements for gaining citizen's rights.

I'm sure I missed some ideas here. What do you guys think?