What is Life

Life is a complex process that as yet defies accurate scientific definition. The eminent biochemist, and Nobel Laureate, Christian de Duve has described life as a system which is able to maintain itself in a state far from equilibrium, grow, and multiply, with the help of a continual flux of energy and matter supplied by the environment. In amplification of this description de Duve defines seven pillars of life which are necessary and sufficient for all forms of life. Thus any living system must have the ability to  

Manufacture its own constituents from materials available from its surroundings  

Extract energy from its environment and convert it into the different forms of work that need to be performed to stay alive  

Catalyse the numerous chemical reactions required to support its activities  

Inform its biosynthetic and other processes about how to guarantee accurate reproduction  

If you call a tail a leg, how many legs has a dog Five No calling a tail a leg doesn t make it a leg. 

Defining the basic living unit as the cell begs the question about what life really is. The separation between living and nonliving is not sharp. Viruses are little more than RNA enclosed in a protein coat. Yet, they reproduce in the right environment of a host cell. Prions are bits of protein that become active within cells, and also reproduce. Neither of these carries on all the functions that we would call life, but they do exhibit some living properties. 

So what are these properties They are numerous and depend on who is doing the listing. Some examples are as follows  

A capacity to reproduce, grow, develop and change over generations. 

Highly complex chemical systems Composed of cells Able to obtain and use energy Able to reproduce using the same genetic mechanism Able to grow and develop 

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We know what the elements are. But what is life From the point of view of natural science, living systems must fulfill three criteria ... 

Eigen M (1995) What will endure of 20th century biology In Murphy MP, O Neill LAJ (Eds) What is Life - The Next Fifty Years. Cambridge University Press, pp 5-23 Garrison WM, Morrison DC, Hamilton JG, Benson AA, Calvin M (1951) Science 114 416 Groth W, Suess H (1938) Naturwissenschaften 26 77... 

Schrodinger, E. (1967). What is Life. Cambridge University Press, Cambridge (1st edn., 1944) Trefil, J. (1987). Meditations at Sunset A Scientist looks at the Sky. Charles Scribner s Sons, New York Ulanowicz, R.E. (1997). Ecology, the Ascendent Perspective. Columbia University Press, New York Weber, B.H., Depew, DJ. and Smith, J.D. (eds.) (1988). Entropy, Information and Evolution. MIT Press, Cambridge, MA... 

Schneider, E.D. and Kay, J.J. (1995). Order from disorder the thermodynamics of complexity in biology. In M.P. Murphy and L.A.J. O Neill (eds.), What is Life - The Next Fifty Years. Cambridge University Press, Cambridge, pp. 161-172... 

Margulis, L. and Sagan, D. (1995). What is Life Simon and Schuster, New York... 

The all-important question would be to know what is life and as per Carl Sagan, the astrophysicist, it is physics as it contains all the elements created by Big-Bang and from supernova explosion of stars and all these are in the domain of physics. 

What are the implications of the Second Law of Thermodynamics for life Erwin Schrodinger, one of the founders of quantum mechanics and a leading figure in twentieth century physics, explored this question in a short book What is Life published in 1944. Schrodinger poses the question in the following way ... 

E. Schrodinger, What is Life Cambridge University Press, London, 1944. This short book by one of the twentieth centuries, leading physicists provides an unusual view of the nature of life. Not all the ideas put forth in this early book are correct, however. 

In his influential philosophical essay What is Life , Schrodinger quotes Miguel de Unamuno Si un hombre nunca se contradice, sera porque nunca dice nada (Translated Should a man never contradict himself, the reason must be that he virtually never says anything at all ) Philosophers have argued that valuable scientific publications must address points of contradiction con-... 

E. Schrodinger (1956) What is Life and Other Scientific Essays, Doubleday, Garden City, New York. 

E. Schrodinger, What Is life Cambridge University Press, Cambride, UK, 1967. 

As already mentioned, along with the question What is life, there was another question on Maturana s agenda, namely What is cognition In general, autopoiesis is concerned with organization, and cognition with the interaction with... 

Schrodinger, E. (1956). What is Life And other Scientific Essays. Cambridge University Press. 

Schrodinger, E. (1944) What Is Life Cambridge University Press, New York. [Reprinted (1956) in What Is Life and Other Scientific Essays, Doubleday Anchor Books, Garden City, NY.]... 

Schrodinger, E. What Is Life Cambridge University Press Cambridge, U.K., 1980. 

Schrodinger E (1944) What is life . Cambridge University Press, Cambridge... 

The very first problem of biology, the question What is life , becomes therefore What is the cell In order to answer this, however, we must recall the answers that have been given in the past to the question What is a living organism ... 

De Loof, A. 1993. Schrodinger 50 years ago What is Life . The ability to communicate , a possible reply International Journal of Biochemistry, 25,1715-1721. 

I had to pay sixpence for admission to the upstairs room at the Swan. The rows of chairs were already packed with interested citizens of every age and calling, who went quiet as a slight man in an untidy wig made his entrance, took his place behind the lectern, and began with a dramatic question What is life ... 

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