Does your cat or dog have a soul? What about a flea?

In the last century, science has undergone several revolutions, with profound implications for answering this ancient spiritual question.

Traditionally, scientists speak of the soul in a materialistic context, treating it as a poetic synonym for the mind. Everything knowable about the "soul" can be learned by studying the functioning of the human brain. In their view, neuroscience is the only branch of scientific study relevant to one's understanding of the soul. The soul is dismissed as an object of human belief, or reduced to a psychological concept that shapes our cognition and understanding of the observable natural world. The terms "life" and "death" are thus nothing more than the common concepts of "biological life" and "biological death."

Of course, in most spiritual and religious traditions, a soul is viewed as emphatically more definitive than the scientific concept. It is considered the incorporeal essence of a person or living thing, and is said to be immortal and transcendent of material existence.

The current scientific paradigm doesn't recognize this spiritual dimension of life. The animating principle in humans and other animals are the laws of physics. As I sit here in my office, surrounded by piles of scientific books and journal articles, I cannot find any reference to the soul or spirit, or any notion of an immaterial, eternal essence that occupies our being. Indeed, a soul has never been seen under an electron microscope, nor spun in the laboratory in a test tube or ultra-centrifuge. According to these books, nothing appears to survive the human body after death.

While neuroscience has made tremendous progress illuminating the functioning of the brain, why we have a subjective experience remains mysterious. The problem of the soul lies exactly here, in understanding the nature of the self, the "I" in existence that feels and lives life. But this isn't just a problem for biology and cognitive science, but for the whole of Western natural philosophy itself.

What we have to understand is that our current worldview −- the world of objectivity and naïve realism -- is beginning to show fatal cracks. Of course, this will not surprise many of the philosophers and other readers who, contemplating the works of men such as Plato, Socrates and Kant, and of Buddha and other great spiritual teachers, kept wondering about the relationship between the universe and the mind of man.

Recently, biocentrism and other scientific theories have also started to challenge the traditional, materialistic model of reality. In all directions, the old scientific paradigm leads to insoluble enigmas, to ideas that are ultimately irrational. But our worldview is catching up with the facts, and the old physico-chemical paradigm is rapidly being replaced with one that can address some of the core questions asked in every religion: Is there a soul? Does anything endure the ravages of time?

Life and consciousness are central to this new view of being, reality and the cosmos. Although the current scientific paradigm is based on the belief that the world has an objective observer-independent existence, real experiments have suggested just the opposite. We think life is just the activity of atoms and particles, which spin around for a while and then dissipate into nothingness like a dust funnel. But if we add life to the equation, we can explain some of the major puzzles of modern science, including Heisenberg's uncertainty principle, the double-slit experiment, entanglement, and the fine-tuning of the laws that shape the universe as we perceive it.

Importantly, this has a direct bearing on the question of whether humans and other living creatures have souls. As Kant pointed out over 200 years ago, everything we experience -- including all the colors, sensations and objects we perceive -- are nothing but representations in our mind. Space and time are simply the mind's tools for putting it all together. Now, to the amusement of idealists, scientists are beginning dimly to recognize that those rules make existence itself possible. Indeed, experiments suggest that particles only exist with real properties if they are observed. One point seems certain: the nature of the universe can't be divorced from the nature of life itself. If you separate them from each other, reality ceases to exist.

We are more than the sum of our biochemical functions. Even the tiniest flea is an incredibly complex living creature, with mouth-parts adapted to feeding on the blood of your cat or dog. They have long legs that allow them to jump up to 13 inches (200 times their own body length, making them one of the best jumpers of all known animals). They have little eyes and antenna, and possess sensory cells that transmit messages to the brain. In fact, they possess all the structures that coordinate sense perception and experience (they can even be trained to perform amazing tricks).

Whether person or flea, the experimental findings of quantum theory suggest that the content of the mind is the ultimate reality, paramount and limitless. Without consciousness, space and time are nothing. From this viewpoint, by virtue of being a living creature, you can never die (see "What Happens When You Die?" and "Is Death the End?"). And the same thing goes for your little dog, too.

Voltaire, the great enlightenment writer and philosopher, once said, "Nobody thinks of giving an immortal soul to a flea." Now, nearly 300 years later, the mass of accumulated scientific evidence suggests we may have to.

Robert Lanza, M.D. has published extensively in leading scientific journals and has over two dozen medical and scientific books, including Biocentrism: How Life and Consciousness Are the Keys to Understanding the True Nature of the Universe. You can learn more about his work at www.robertlanza.com.