In the womb, an embryo is exposed to numerous hormones and nutrients that determined the health and viability of the embryo. The mix of these chemicals and even the temperature of the womb are determined by the host's DNA. In the late 21th century when cloning became not just a science but an industry, scientists recognized this symbiosis, developing sophisticated mechanized wombs to "nurture" a clone through gestation. SF writers of old envisioned armies of workers and soldiers jumping into action straight out of the cloning tubes. In reality though, the main beneficiary of the new industry were the upper classes, who could now produce the perfect offspring. "Smarties" as they were soon nicknamed, slowly took the lead of humanity, with perfect bodies and IQs easily surpassing 300. Greater efficiency of leadership led to increased productivity, and the world of science benefitted as well, since some of the Smarties choose to use their great minds in the pursuit of knowledge, not power.