Simply put, none of these scenarios are plausible for the immediate future. If there is something next, some imminently arriving transformative development for human capabilities, then the key will not be improved genes or cortical plug-ins. But what other way forward could humans possibly have? With genetic and cyborg enhancement off the table for many years, it would seem we are presently stuck as-is, sans upgrades.

There is, however, another avenue for human evolution, one mostly unappreciated in both science and fiction. It is this unheralded mechanism that will usher in the next stage of human, giving future people exquisite powers we do not currently possess, powers worthy of natural selection itself. And, importantly, it doesn't require us to transform into cyborgs or bio-engineered lab rats. It merely relies on our natural bodies and brains functioning as they have for millions of years.

This mystery mechanism of human transformation is neuronal recycling, coined by neuroscientist Stanislas Dehaene, wherein the brain's innate capabilities are harnessed for altogether novel functions.

This view of the future of humankind is grounded in an appreciation of the biologically innate powers bestowed upon us by hundreds of millions of years of evolution. This deep respect for our powers is sometimes lacking in the sciences, where many are taught to believe that our brains and bodies are taped-together, far-from-optimal kluges. In this view, natural selection is so riddled by accidents and saddled with developmental constraints that the resultant biological hardware and software should be described as a "just good enough" solution rather than as a "fine-tuned machine."

So it is no wonder that, when many envisage the future, they posit that human invention-whether via genetic engineering or cybernetic AI-related enhancement-will be able to out-do what evolution gave us, and so bootstrap our species to a new level. This rampant overoptimism about the power of human invention is also found among many of those expecting salvation through a technological singularity, and among those who fancy that the Web may some day become smart.

The root of these misconceptions is the radical underappreciation of the design engineered by natural selection into the powers implemented by our bodies and brains, something central to my 2009 book, The Vision Revolution. For example, optical illusions (such as the Hering) are not examples of the brain's poor hardware design, but, rather, consequences of intricate evolutionary software for generating perceptions that correct for neural latencies in normal circumstances. And our peculiar variety of color vision, with two of our sensory cones having sensitivity to nearly the same part of the spectrum, is not an accidental mutation that merely stuck around, but, rather, appear to function with the signature of hemoglobin physiology in mind, so as to detect the color signals primates display on their faces and rumps.

These and other inborn capabilities we take for granted are not kluges, they're not "good enough," and they're more than merely smart. They're astronomically brilliant in comparison to anything humans are likely to invent for millennia.

Neuronal recycling exploits this wellspring of potent powers. If one wants to get a human brain to do task Y despite it not having evolved to efficiently carry out task Y, then a key point is not to forcefully twist the brain to do Y. Like all animal brains, human brains are not general-purpose universal learning machines, but, instead, are intricately structured suites of instincts optimized for the environments in which they evolved. To harness our brains, we want to let the brain's brilliant mechanisms run as intended-i.e., not to be twisted. Rather, the strategy is to twist Y into a shape that the brain does know how to process.

But how do I know this is feasible? This tactic may use the immensely powerful gifts that natural selection gave us, but what if harnessing these powers is currently far beyond us? How do we find the right innate power for any given task? And how are we to know how to adapt that task so as to be just right for the human brain's inflexible mechanisms?

I don't want to pretend that answers to these questions are easy-they are not. Nevertheless, there is a very good reason to be optimistic that the next stage of human will come via the form of adaptive harnessing, rather than direct technological enhancement: It has already happened.

We have already been transformed via harnessing beyond what we once were. We're already Human 2.0, not the Human 1.0, or Homo sapiens, that natural selection made us. We Human 2.0's have, among many powers, three that are central to who we take ourselves to be today: writing, speech, and music (the latter perhaps being the pinnacle of the arts). Yet these three capabilities, despite having all the hallmarks of design, were not a result of natural selection, nor were they the result of genetic engineering or cybernetic enhancement to our brains. Instead, and as I argue in both The Vision Revolution and my forthcoming Harnessed, these are powers we acquired by virtue of harnessing, or neuronal recycling.

In this transition from Human 1.0 to 2.0, we didn't directly do the harnessing. Rather, it was an emergent, evolutionary property of our behavior, our nascent culture, that bent and shaped writing to be right for our visual system, speech just so for our auditory system, and music a match for our auditory and evocative mechanisms.