Origin and Nature of the Living Cell

Pier Luigi Luisi is a visionary biochemist who has the imagination and the courage to integrate philosophy in his pioneering research on minimal cells, or protocells. His laboratory in Rome is one of just five or six that are trying to bring forth a living cell from organic components. Luisi is also the author of 10 books, among them: The Emergence of Life: From Chemical Origins to Synthetic Biology; Mind and Life; Giant Vesicles; Chemical Synthetic Biology; and The Minimal Cell. Most recently he co-athored with Fritjof Capra, The Systems View of Life: A Unifying Vision.

Luigi graciously sat down with me on July 12, 2014, after the Origins 2014 International Conference of Astrobiology in Nara.

Ion Soteropoulos. As a philosopher and metaphysician, I am interested in the problem of whether and how life could emerge from non-life. Indeed, the problem of determining the origin of life is essentially the philosophical problem of motion or change that is, how something B is derived from something entirely different A is a problem that was debated in Greek Ionian philosophy twenty-six hundred years ago (see Anaxagoras and Zeno of Elea fifth century BCE). It has been unanimously accepted by natural philosophers and mathematicians since ancient times, that motion between successive and contradictory opposites A and B is logically and physically impossible.

If it is impossible to pass successively (via a series of steps of increasing complexity) from A to B, from not-life to life, then the fundamental assumption of abiogenetic biology that life evolved from non-life is false a delusion.

What is your thesis concerning this critique of evolution and linear time as a method for producing and operating life, and more generally as a method for producing change and variety?

Pier Luigi Luisi. Modern science has a different vision and a different language to approach the problem of life and the origin of life. The Greek Ionian point of view may be interesting to historians, as it may be that of Plato or Aristotle, but is not relevant now. There have been many theories about life and the origin of life in the past thousand years, and each is worth examining in the history of science or the history of philosophy, but they are not relevant for approaching the question now. The first property of science is that it changes its paradigms and vision according to discoveries, and this means that old things like abiogenesis, vitalism, and creationism belong to the past, to history.

Modern science sees life first of all as a system: the life of a microbe is the entire microbial system; life is the entire web of chemical interactions, including interactions with the environment. Likewise, the life of a human being is the integrated system of all organs, cells, tissues, and mind processes that produce a biologically autonomous unity. Death, by contrast, is fragmentation: that is, it occurs when all of these parts no longer “talk” with one another. A single element does not make any sense, just as the single individual does not make any sense without the society of people in which he or she is immersed.

This being the case, the origin of life is seen as the process of emergence, when the single parts, given certain conditions, begin to interact with one another. Life is an emergent property, as the single elements of a bacterium lipids and DNA and proteins and sugars — are per se not living. Life results when all these elements form a system of mutual cooperation.Thus, we do not have in science the notion of an A becoming a B to consider life as motion or change of motion.

Life is never a single thing:The origin of life is the acquisition of the stable system structure mentioned above. Science does not yet have all the steps to elucidate and understand this process — this is actually the research in which many scientists have been involved for the last sixty years or so, which is really not that many years compared to other branches of science. And it is accepted and even proved that you can pass from non-life to life through a series of steps of increasing complexity, but keeping in mind the notions of emergence and system view.

I.S. The origin-of-life research poses two fundamental questions:

1. What is the founding principle of life?

2. What is the founding principle of converting non-living constituent parts into a living whole and vice versa? In other words, what is the founding principle of reversible change or motion between opposites?

Have you done any research on these questions? Is it possible, somehow, to synthesize a minimal complete living cell out of organic molecules without knowing the founding principle of life? Going deeper, is it possible to synthesize a minimal complete living cell out of inorganic ingredients? And, then, is it possible to synthesize a minimal complete living cell out of the ultimate constituents of matter?

Pier Luigi Luisi. What I said above answers the first and most of the second point of this new question. And the additional basic point is, that I and with me most scientists do not see life and non-life as two opposites in the universe. They are complementary: there is no life without death, and between the inorganic, organic, and biological world there is the principle of continuity, as we call it, according to which there is no qualitative jump of quality among these 3 classes of chemistry. This distinction between life and non-life that most people make, is just a projection based on the assumption that life is something magic and different from matter. Life for science is organized chemical matter see the theory of autopoiesis. And this be careful now does not mean that you can explain life in terms of atoms or molecules; that would be simplistic reductionism. Life forms from atoms and molecules that make the structure, but not the quality of life.

Life as a property cannot be explained in terms of the properties of atoms and molecules. You cannot do that because at each new level of complexity new properties arise (emergence) that are not present in the constituent parts and which cannot be explained on the basis of the properties of the constituent parts. For example, the properties of hemoglobin cannot be explained in terms of the properties of the isolated four chains; it is only when the four chains interact with one another, that the respiratory properties of hemoglobin appear (again emergence).

Concerning my research on the minimal cell, and that of many colleagues, the answer is yes, we believe it is possible to construct in the laboratory this kind of minimal living entity, but it is not true that we do not know the basic principles of life. I believe we know them well, at least at the level of simple cells. There are still technical difficulties, but they will be eliminated in the next few years.

Note: The fact that life is constituted by molecules does not at all deny the beauty and sacredness of life. The only fundamental difference with the past, dominated by religion, is that concepts such as the mind, consciousness, love, spirituality and ethics are seen as immanent things, self-generated values at the level of the complexity of the human being.

I.S. During an interview with Suzan Mazur, you said the essence of life is self-maintenance: that is, the capacity of living beings (bacteria, elephants, trees) to remain themselves despite the thousands and thousands of transformations going on inside their structure. Now the same property characterizes nature, matter or the universe. Indeed according to Aristotle’s famous definition, nature is the principle and cause of rest and motion residing within the thing by essence and not by accident (Physics II, 192b). This means that nature, matter, or universe is a complex whole uniting opposites such as rest and motion. This unity ensures the constancy and continuity of the physical whole’s self-motion, and the constancy and sameness of its being despite the disruptive nature of its motion and variation. It follows that life is an immanent quality and principle of nature, matter, or the universe; that everything in the universe is a living being a soul or anima endowed with the power of continuous self-motion. We call this doctrine “animism”.

Do you think that biology in its fundamental nature is animistic leading us to a Platonic biocosmology, defined as “the science of the cosmos thought of as a living whole”?

Pier Luigi Luisi. Here we go toward more detailed and difficult levels of discussion. The essence of life, according to the theory of autopoiesis, is indeed self-maintenance due to a self-generation process from within. Now, if you equate autopoiesis with life, you would indeed conclude that any autopoietic system is living. A more sophisticated view is this: Autopoiesis is the necessary not a sufficient condition for life.

In the laboratory I have constructed autopoietic micelles and vesicles, globular structures that for a certain short period of time, are self-maintaining due to internal processes of self-regeneration of the components, but I would not call these micelles “living”. Likewise, I would say that Gaia, our Earth, is an autopoietic system, capable of self-generation, but I would not call Gaia “living”. In order to have life, in addition to autopoiesis, you must have cognition. And here, as I said, things become subtle and more complex, and there is no general consensus even among the researchers involved in autopoiesis. In fact, the term “cognition”, also a product of the autopoietic theory of Maturana and Varela, is not a clearly definable property. To me, to call Gaia and perhaps the universe autopoietic that is, self-regulatory and self-maintaining is already a great vision. I do not need to add the adjective of living, as we would then plunge into vagueness and even confusion.

I.S.What is biology’s next revolution?

Pier Luigi Luisi.I do not think there will be a revolution, in the sense of some brand new general paradigm. Biology will continue to expand in terms of basic and applied molecular biology, whereby “applied” means, essentially, genetic engineering or, in other words synthetic biology, with the social and ethical problems this may entail. In the next ten years there will most probably be the synthesis in laboratory of minimal life: that is, of the simplest forms of microbial life. Personally, however, I do hope that there will be self-imposed limits to genetic synthetic biology, as we should stay away from cloning or genetic modifications of higher organisms.

Biology will expand also in the area of medicine, and the development of stem cells will probably give us much progress in several types of treatment. From the conceptual side, I see biology becoming more and more system biology: a biological function or organ will be seen not in terms of a single, localized mechanism, but rather in terms of the web of relations that link this function or organ to the entire web of life.

Contact information: luisi@mat.eth.ch