Created by Dr Michael Grant, a Washington DC based scientist, the original purposes of Cortexin was lost to history – along with its creator and all his notes – when a nuclear war broke out. Grant’s test animals, who had been injected with the drug, escaped in the course of the devastation that followed.
It was at this point that what was presumably an unintended side effect, the animals dosed with Cortexin proved to been altered on a genetic level. Over the course of several generations, they developed greater intelligence, bipedal locomotion, hands with opposable thumbs, and even the power of speech.
A variety of species were used by Grant in his experiments, including apes, bats, dogs, gophers, leopards, lions, pumas, rats, sloths, tigers and wolves. The wide range of species, and the fact that each of them had a large enough population to be able to breed viably, along with the location of Grant’s researches, strongly suggests that his experiments were funded by the Pentagon.
NB: there is no known connection between this Cortexin and the real world drug of the same name.