Science fiction writers traffic in a world that tries on possible worlds. What if, as in the Hollywood blockbuster Minority Report, we could read people's intentions before they act and thus preempt violence? An intentionality detector would be a terrific device to have, but talk about ethical nightmares. If you ever worried about big brother tapping your phone lines, how about tapping your neural lines? What about aliens from another planet? What will they look like? How do they reproduce? How do they solve problems? If you want to find out, just go back and watch reruns of Star Trek, or get out the popcorn and watch Men In Black, War of the Worlds, The Thing, Signs, and The Blob.

But here's the rub on science fiction: it's all basically the same stuff, one gimmick with a small twist. Look at all the aliens in these movies. They are always the same, a bit wispy, often with oversized heads, see through body parts, and with awesome powers. And surprisingly, this is how it has been for 75 or so years of Hollywood, even though our technologies have greatly expanded the range of special effects that are possible. Why the lack of creativity? Why such a poverty of the imagination?

The answer is simple, and reveals a deep fact about our biology, and the biology of all other organisms. The brain, as a physical device, evolved to process information and make predictions about the future. Though the generative capacity of the brain, especially the human brain, is spectacular — providing us with a system for massive creativity, it is also highly constrained. The constraints arise from both the physics of brain operation, as well as the requirements of learnability.

These constraints establish what we, and other organisms have achieved — the actual — and what they could, in the future and with the right conditions, potentially achieve — the possible. Where things get interesting is in thinking about the unimaginable. Poof! But there is a different way of thinking about this problem that takes advantage of exciting new developments in molecular biology, evolutionary developmental biology, morphology, neurobiology, and linguistics. In a nutshell, for the first time we have a science that enables us to understand the actual, the possible and the unimaginable, a landscape that will forever change our understanding of what it means to be human, including how we arrived at our current point in evolutionary theory, and where might end up in ten or ten million years.

To illustrate, consider a simple example from the field of theoretical morphology, a discipline that aims to map out the space of possible morphologies and in so doing, reveal not only why some parts of this space were never explored, but also why they never could be explored. The example concerns an extinct group of animals called the ammonoids, swimming cephalopod mollusks with a shell that spirals out from the center before opening up.

In looking at the structure of their shells — the ones that actually evolved that is — there are two relevant dimensions that account for the variation: the rate at which the spiral spirals out and the distance between the center of this coil or spiral and the opening. If you plot the actual ammonoid species on a graph that includes spiral rate and distance to the opening, you see a density of animals in a few areas, and then some gaps. The occupied spaces in this map show what actually evolved, whereas the vacant spaces suggest either possible (not yet evolved) or impossible morphologies.

Of great interest in this line of research is the cause of the impossible. Why, that is, have certain species never taken over a particular swath of morphological turf? What is it about this space that leaves it vacant? Skipping many details, some of the causes are intrinsic to the organisms (e.g., no genetic material or developmental programs for building wheels instead of legs) and some extrinsic (e.g., circles represent an impossible geometry or natural habitats would never support wheels).

What is exciting about these ideas is that they have a family resemblance to those that Noam Chomsky mapped out over 50 years ago in linguistics. That is, the biology that allows us to acquire a range of possible languages, also puts constraints on this system, leaving in its wake a space of impossible languages, those that could never be acquired or if acquired, would never remain stable. And the same moves can be translated into other domains of cultural expression, including music, morality, and mathematics. Are there musical scores that no one, not even John Cage, could dream up because the mind can't fathom certain frequencies and temporal arrangements? Are there evolvable moral systems that we will never see because our current social systems and environments make these toxic to our moral sensibilities? Regardless of how these questions are resolved, they open up new research opportunities, using methods that are only now being refined.

Here are some of my favorites, examples that reveal how we can extend the range of the possible, invading into the terra incognita of the impossible. Thanks to work by neuroscientists such as Evan Balaban, we now know that we can combine the brain parts of different animals to create chimeras. For example, we can take the a part of a quail's brain and pop it into a chicken and when the young chick develops, it head bobs like a quail and crows like a chicken.

Functionally, we have allowed the chicken to invade an empty space of behavior, something unimaginable, to a chicken that is. Now let your imagination run wild. What would a chimpanzee do with the generative machinery that a human has when it is running computations in language, mathematics and music? Could it imagine the previously unimaginable? What if we gave a genius like Einstein the key components that made Bach a different kind of genius? Could Einstein now imagine different dimensions of musicality? These very same neural manipulations are now even possible at the genetic level. Genetic engineering allows us to insert genes from one species into another, or manipulate the expressive range of a gene, jazzing it up or turning it off.

This revolutionary science is here, and it will forever change how we think. It will change what is possible, potentially remove what is possible but deleterious, and open our eyes to the previously impossible.