Scientists have discovered a way of manipulating a gene that turns animals into drones that do not become bored with repetitive tasks. The experiments, conducted on monkeys, are the first to demonstrate that animal behaviour can be permanently changed, turning the subjects from aggressive to compliant" creatures. The genes are identical in humans and although the discovery could help to treat depression and other types of mental illness, it will raise images of the Epsilon caste from Aldous Huxley's futuristic novel Brave New World. The experiments... involved blocking the effect of a gene called D2 in a particular part of the brain. This cut off the link between the rhesus monkeys' motivation and reward. Instead of speeding up with the approach of a deadline or the prospect of a "treat," the monkeys in the experiment could be made to work just as enthusiastically for long periods. The scientists say the identical technique would apply to humans. [They] found that they could make the monkeys work their hardest and fastest all the time, without any complaint or sign of slacking, just by manipulating D2 so that they forgot about the expectation of reward. Methods of manipulating human physical and psychological traits are just around the corner, and the technology will emerge first as a lucrative add-on available from in vitro fertilization clinics. "There's no doubt we will be able to influence behaviour," said Julian Savulescu, a professor of ethics at Oxford University.