Although physical enhancement is what most people associate with transhumanism, it's not particularly interesting. A man with tentacles and wings who can fly and breathe underwater is still just some dude. Humans are primitive beings, with conspicuously primitive minds -- we just recently evolved from un-intelligent apes that used the same stone tools for millions of years.
Everything truly exciting about the transhumanist project lies in the mental realm. Only through opening up and intervening in the brain can we really change ourselves and the way the world works. Anything else is just the surface.
What approaches can we take to cognitive enhancement?
First, take brain surgery. It is extremely unlikely that cognitive enhancement will be conducted through conventional brain surgery as is practiced today. These procedures are inherently risky and only conducted under necessary circumstances, when the challenges of surgery outweigh the huge cost, substantial risk, and long recovery time of the procedures.
More subtle than brain surgery is optogenetics, regarded by some as the scientific breakthrough of the last decade. Optogenetics allows researchers to control the precise activation of neurons through the introduction of light-sensitive genes to animal brain tissue.
Optogenetics is unlikely to be applied to humans before 2030-2040, for two reasons. The first is that it involves the introduction of foreign genes into human brain tissue, and gene therapy is in its infancy -- treatments derived from gene therapy are extremely rare and highly experimental. People have been killed by gene therapy gone awry. When gene therapy research moves in the direction of human enhancement, a massive backlash seems plausible. It may be banned entirely for enhancement purposes.
At the very least, the short-lived nature of gene therapy and problems with viral vectors ensure that gene therapy will stay experimental until entirely new vectors are developed. Chromallocytes are the ideal gene delivery vector, but those are quite far off. Is there something between current vectors and chromallocytes that produces safe, predictable gene therapy results? That is a great big question mark. What is needed is not one or two breakthroughs, but a long series of many breakthroughs. I challenge readers to find anyone in biotech who would bet that gene therapy will be made safe, predictable, and approved for use in humans within 10 years, 20 years, or 30. Developing new basic capabilities in biotech is a long, drawn out process.
The second reason optogenetics will not bear fruit for cognitive enhancement before 2030-2040 is that it requires slicing off part of the scalp and mounting fiber optics directly on the skull. This is all well and good for animals, which we torment with abandon, but it seems unlikely to be popular among the Homo sapiens crowd. Mature regenerative medicine would be necessary to heal tissue damage from this procedure.
According to Ray Kurzweil's scenario, "nanobots" will be developed during the late 2020s which will be injected into the human body by the trillions, where they can link up with neurons and augment the brain from the inside.
However, given the near complete lack of progress towards molecular nanotechnology since Eric Drexler wrote Engines of Creation in 1986, I find this hard to believe. Nanobots require nanofactories, nanofactories require assemblers, and assemblers would be highly complex aggregates of millions of molecules that themselves would need to be manufactured to atomic precision. Today, all objects manufactured to molecular precision have negligible complexity. The imaging tools that exist today -- and for the foreseeable future -- are far too imprecise to allow for troubleshooting molecular systems of non-negligible size and complexity that refuse to behave as intended. The more precise the imaging method, the more energy is delivered to the molecular structure, and the more likely it is to be blown into a million little pieces.
It is difficult to understate how far we are from developing autonomous nanobots with the ability to perform complex tasks in a living human body. There is no reason to expect a smooth path from today's autonomous MEMS (micro-electro-mechanical systems) to the "nanobots" of futurist anticipation. Autonomous MEMS are early in their infancy. Assemblers are probably a necessary prerequisite to miniature robotics with the power to enhance human cognition. No one has designed anything close to an assembler, and if progress continues as it has for the last 25 years, it will be many decades before one is developed.
So, that is three technologies that I have argued will not be applied to cognitive enhancement in the foreseeable future -- brain surgery, optogenetics, and nanobots.