“An animal’s behaviour tends to maximize the survival of the genes ‘for’ that behaviour, whether or not those genes happen to be in the body of the particular animal performing it.”
– Richard Dawkins, The Extended Phenotype
When a mainstream movie explores even the slightest hint of a contemporary scientific concept there is reason for excitement. Too often the world of science seems like an estranged sibling of the mainstream entertainment industry, the quiet cousin nobody is interested in talking to at the family gathering. And that is why, all other critical responses aside, one cannot help but feel joy for the central role of the nervous system in Avatar.
Gaps in logic also aside—and there are some significant ones—the biological world of Pandora in James Cameron’s film is modeled as a planet-wide neural network with animals living in it that can literally plug into one another’s nervous system. In one of the first examples of this animal-to-animal interface in the film, Neytiri, one of the indigenous Na’vi inhabiting Pandora, leads our protagonist to the top of a rocky outcropping and demonstrates her bond with an Ikran, a dragon-like bird. Neytiri extends her ponytail to reveal a cluster of nerve-like filaments at the tip, which she touches to a similar bundle on the Ikran. The filaments fuse, and we watch as she mounts the beast and is able to exert directional control over it. At first quite menacing and flapping about, the Ikran now becomes calm and controlled by means of the symbiotic bond achieved through the fusion of their nervous systems.
Another neuroscientific theme is presented when we learn that the neural interfaces extend beyond the level of the paired individual organisms and include the entire planet’s ecosystem, which is primarily composed of trees with roots that connect to one another and exchange electrochemical information like neurons in a brain. At various points we witness the Na’vi plugging into this tree network and hearing voices of their ancestors, as if their memories had been uploaded this planet-wide neural net to be accessed at a later date. During religious ceremonies, we see the Na’vi plugged into the forest floor around the central Tree of Souls, waving in unison.
The last ripple to the neuroscience of Pandora is the presence of a spirit in the planet’s nervous system, called Eywa, which suggests that the entire system has some sort of emergent sentience—but to investigate this line of deduction any further would only be to peek into one of the ultimately blurred logical systems in Cameron’s para-scientific world. The science works for the story: it gives us enough sense of an all-encompassing, all-connected life force to assuage the spiritualists but at the same time grounds this force in filaments and neuro-talk to keep things rooted in the physical world. To try to unify these forces into a logical, scientifically sound system or to explain how much intelligence the planet really has were tasks Cameron probably didn’t have time to fully develop, nor is it our concern here.
What Avatar does raise are some fascinating possibilities—and potential limitations—of brains, as we consider both the future of our own species and the potential of discovering a planet like Pandora with a highly interconnected, global nervous system. After a conversation with re:COGNITION author and sharp evolutionary biologist Sam McDougle, I began to think about many of the neuroscientific concepts in Avatar in terms of Richard Dawkins’ theory of the extended phenotype, which argues that we should look beyond the neat segregations of genomes into their “replicator vehicles” (the organisms themselves) and to instead try to see a broad biological community with extensive interaction between organisms and their environment. Examples abound in Dawkins’ text of animals whose genes lead them to create or scavenge for artifacts—shells, burrows, or perhaps a cathedral mound, in the case of the termite
—that end up playing a role in their fitness and reproductive success. Dawkins’ reasoning leads to the conclusion that the phenotype of animals should include objects that, like their heart or any other vital organ, become integral to their survival.
Taking Dawkins’ idea of the extended phenotype and applying it to a more neurocentric approach in Avatar, we can begin to detect some contemporary scientific work, such as modern brain-computer interface research and Ramachandran’s infamous phantom limb experiments that parallel some of the Avatar concepts of extended neural networks (and thus extended phenotypes) and “plugging in” to external banks of senses and memories. Ramachandran’s unveiling of the phantom limb phenomenon, in which a patient who has lost a limb is tricked through their visual system into feeling touch sensations being acted upon another individual’s hand as if it were their own, demonstrated that our nervous system is not a fully contained, self-centered purist—it can be tricked, perhaps through the activation of the always trendy “mirror neuron” systems which seem to fire while we observe someone else in action, into integrating the experience of another organism into our first-person experience, with activation seen in the same regions of cortex as the amputee’s “phantom” hand was being touched– a case of one sensory modality receiving foreign input but still making its way into conscious feeling. Likewise, in Avatar, as Jake mounts one of the horses on Pandora for the first time and plugs in his filaments, he feels the “heartbeat,” “muscles,” and “breathing” of the beast—then uses his own executive system to guide it through the landscape. Perhaps the future will bring more instances, building on Ramachandran’s experiments, where we more directly interface with the brains of other individuals (or even other animals) to receive sensory input and thereby extend our phenotype. In a way this has already started, albeit digitally: one of the most active fields of neuroscientific research around the world is that of brain-computer interfaces, where electrodes in pre-motor cortex can drive the action of a prosthetic hand, which can provide sensory input back into the cortex. These interfaces will undoubtedly yield some of the most remarkable developments in this century of scientific research.
Yet we are still on the level of the individual—what does modern neuroscience tell us about the possibility of a vast network of biologically stored memory in the trees of Pandora? Though we are still blind to the translation of cellular firing into subjective perceptions, researchers are already beginning to manipulate and understand small segments of neural tissue that can store patterns of activation. If larger and larger models are created and we can begin to correlate subjective memory retrieval in an organism to the precise patterns of spatiotemporal firing of neurons, then perhaps we will move closer to bridging the explanatory gap (massive modeling initiatives such as the Blue Brain Project could do just that). The question lingers of whether we could achieve anywhere near the kind of biological unity of the Na’vi in Avatar. Cameron may be right– our future could, whether we like it or not, consist of a lot of laying on our backs under a piece of machinery that takes us somewhere else and less of moving our actual physical body through space.
Even if our future is all digital, researchers are still attempting to unlock the biological secrets of how coalitions of neurons encode and store memories– we’ll need this information before we can hope to truly interface our nervous systems with another entity, be it biological or otherwise. Phillip Larimer and Ben Strowbridge of Case Western Reserve University published a study in this month’s edition of Nature Neuroscience in which they were able to store short patterns of activation in rat hippocampal slices that persisted after the removal of the original stimulus. Such studies mark the beginning of engineering memory into a neural network such as that on Pandora—if we can scale up our models and correlate subjective perceptions with cellular activity, it may be possible to offload—or at least digitally simulate and record—one’s own memories in an external network for safe keeping. Yet there are deep fissures in our understanding of what is possible when it comes to accessing another individual’s patterns of neuronal activity and the memory encoded therein: one can easily argue that you’d need to live an entire life of sensory experience in another person’s shoes in order to have access to the nuances of their memory, or even to see a color the way they do. Whether humans can ever have something like the Na’vi’s vast biological information network (not the Internet) in which the first-person memories of ancestors are stored and accessed will remain a question of science fiction for some time. Until then, long live the memoir.
In the end what is rewarding about the inklings of neuroscience in a film like Avatar is the fact that it will reach millions of viewers who may otherwise have had no exposure to these concepts. There is plenty of pseudo-science to be nitpicked, but the fact remains that physical neuroscience gets its share of the spotlight in the film, from the filaments that bond creatures together to the unveiling of the planet as a network of trees “communicating like neurons in a brain.” The tree is a fitting visual analogy– one with roots in the classic work of Santiago Ramon y Cajal, the father of modern neuroscience, who turned a childhood fascination with the branches above him into a lifelong investigation of the branches within him. And now it could be the very analogy that excites millions more to take interest in the scientific field that will define the 21st century.
- Richard Dawkins‘ extended phenotype.
- Larimer and Stowbridge, “Representing information in cell assemblies: persistent activity mediated by semilunar granule cells.” Nature Neuro, Jan. 2010.
- Ramachandran’s phantom limb experiments.