Parallax describes the apparent change in the direction of a moving object caused by alteration in the observer's position. In the graphic work of M.C. Escher, human faculties are similarly deceived and an impossible reality made plausible.

While not strictly a scientific theorem, anthropocentrism, the assessment of reality through an exclusively human perspective, is deeply embedded in science and culture. Improving knowledge requires abandoning anthropocentricity or, at least, acknowledging its existence.

Anthropocentrism's limits derive from the physical constraints of human cognition and specific psychological attitudes. Being human entails specific faculties, intrinsic attitudes, values and belief systems that shape enquiry and understanding.

The human mind has evolved a specific physical structure and bio-chemistry that shapes thought processes. The human cognitive system determines our reasoning and therefore our knowledge. Language, logic, mathematics, abstract thought, cultural beliefs, history and memories create a specific human frame of reference, which may restrict what we can know or understand.

There may be other forms of life and intelligence. The ocean has revealed creatures that live from chemo-synthesis in ecosystems around deep-sea hydrothermal vents, without access to sunlight. Life forms based on materials other than carbon may also be feasible. An entirely radical set of cognitive frameworks and alternative knowledge cannot be discounted.

Like a train that can only run on tracks that determine direction and destination, human knowledge may ultimately be constrained by what evolution has made us.

Knowledge was originally driven by the need to master the natural environment to meet basic biological needs—survival and genetic propagation. It was also needed to deal with the unknown and forces beyond human control. Superstition, religion, science and other belief systems evolved to meets these human needs.

In the eighteenth century, medieval systems of aristocratic and religious authority were supplanted by a new model of scientific method, rational discourse, personal liberty and individual responsibility. But this did not change the basic underlying drivers.

Knowledge is also influenced by human factors—fear and greed, ambition, submission and tribal collusion, altruism and jealousy, as well as complex power relationships and inter-personal group dynamics. Behavioural science illustrates the inherent biases in human thought.

Announcing a boycott of certain "luxury" scientific journals, 2013 Nobel laureate Dr. Randy Schekman argued that to preserve their pre-eminence they acted like "fashion designers who create limited-edition handbags or suits…know[ing] scarcity stokes demand". He argued that science is being distorted by perverse incentives whereby scientists who publish in important journals with a high "impact factor" can expect promotion, pay rises and professional accolades.

Understanding operates within these biological and attitudinal constraints. As Friedrich Nietzsche wrote: "every philosophy hides a philosophy; every opinion is also a hiding place, every word is a mask".

Understanding of fundamental issues remains limited. The cosmological nature and origins of the universe are contested. The physical source and nature of matter and energy are debated. The origins and evolution of biological life remain unresolved.

Resistance to new ideas frequently restricts the development of knowledge. The history of science is a succession of controversies—a non geo-centric universe, continental drift, theory of evolution, quantum mechanics and climate change.

Science, paradoxically, seems to also have inbuilt limits. Like an inexhaustible Russian doll, quantum physics is an endless succession of seemingly infinitely divisible particles. Werner Heisenberg's uncertainty principle posits that human knowledge about the world is always incomplete, uncertain and highly contingent. Kurt Gödel's incompleteness theorems of mathematical logic establish inherent limitations of all but the most trivial axiomatic systems of arithmetic.

Experimental methodology and testing is flawed. Model predictions are often unsatisfactory. As Nassim Nicholas Taleb observed: "You can disguise charlatanism under the weight of equations … there is no such thing as a controlled experiment."

Challenging anthropocentrism does not mean abandoning science or rational thought. It does not mean reversion to primitive religious dogma, messianic phantasms or obscure mysticism.

Transcending anthropocentricity may allow new frames of reference expanding the boundary of human knowledge. It may allow human beings to think more clearly, consider different perspectives and encourage possibilities outside the normal range of experience and thought. It may also allow a greater understanding of our existential place within nature and in the order of things.

As William Shakespeare's Hamlet cautioned a friend: "There are more things in heaven and earth, Horatio, than are dreamt of in your philosophy".

But fundamental biology may not allow the required change of reference framework.

While periodically humbled by the universe, human beings remain enamoured, for the most part, with the proposition that they are the apogee of development. But as Mark Twain observed in Letters from Earth: "He took a pride in man; man was his finest invention; man was his pet, after the housefly."

Writing in The Hitchhikers' Guide to the Galaxy, the late English author Douglas Adams speculated that the earth was a powerful computer and human beings were its biological components designed by hyper-intelligent pan-dimensional beings to answer the ultimate questions about the universe and life. To date, science has not produced a conclusive refutation of this whimsical proposition.

Whether or not we can go beyond anthropocentrism, it is a reminder of our limits. As Martin Rees, Professor of Cosmology and Astrophysics, at Cambridge and Astronomer Royal, noted:

 "Most educated people are aware that we are the outcome of nearly 4 billion years of Darwinian selection, but many tend to think that humans are somehow the culmination. Our sun, however, is less than halfway through its lifespan. It will not be humans who watch the sun's demise, 6 billion years from now. Any creatures that then exist will be as different from us as we are from bacteria or amoebae."