They have explored that solution and found it much harder than creating a safe superintelligence from scratch. To use an analogy: We don't build submarines by u

They have explored that solution and found it much harder than creating a safe superintelligence from scratch. To use an analogy: We don't build submarines by upgrading fish, and we don't build passenger jets by upgrading birds. The human brain is some of the worst spaghetti code imaginable. It has no API, no documentation, and no abstractions. Worse, human brains do not have stable values over time. Someone at age 60 won't value the same things they did at age 20, and this is not just due to new knowledge. That's a deal-breaker for a superintelligence. Solving these problems is likely much harder than making AI de novo. Bostrom himself devoted a decent chunk of Superintelligence to biological enhancement. His conclusion was that genetic engineering through iterated embryo selection could get us some IQ 200+ minds. These people would have more cognitive horsepower than any mind in history, including greats like John von Neumann and John Conway, but they would not be superintelligent. Also, Bostrom concluded that somatic gene therapy and brain-computer interfaces were unlikely to help. And as a practical matter, humans take 20+ years to reach maturity. Many forecasts put artificial superintelligence only a generation or two away, at which point all biological systems would be superseded. Biological enhancement may help to create better AI researchers, but they're not the end-game.