Even if scientists find the right genes and “turn them on,” there is no guarantee that people will actually be smarter.In fact, some scientists speculate that trying to ramp up intelligence – whether by biology or machines – could overload the brain’s carrying capacity.According to Martin Dresler, an assistant professor of cognitive neuroscience at Radboud University in the Netherlands, some researchers believe that “evolution forced brains to develop toward optimal … functioning.” In other words, he says, “if there still was potential to optimize brain functioning by adding certain chemicals, nature would already have done this.” The same reasoning could also apply to machine enhancement, Dresler adds.Even the optimistic Sandberg says that enhancing the brain could prove more difficult than some might imagine because changing biological systems can often have unforeseen impacts.“Biology is messy,” he says.“When you push in one direction, biology usually pushes back.”

THE FUTURE OF BLOOD

Given the brain’s importance, cognitive enhancement might be the holy grail of transhumanism.