Do we now have a valid Universal Definition and Test for 'Life'?

Definition and test for life
Name:
Institution:
Date:
There is no universally accepted definition of living and life, but most definitions incorporate the shared characteristics of living things. Thus, the study of life has mostly focused on living organisms on planet earth. With the continued growth in technological know-how in spacecraft manufacture and outersapce exploration, the debate has been reignited once again. To gain a better understanding of what constitutes life, many scientists have integrated biological explanations with astronomy in expanding the functioning and composition of living tissues (Bortz, 2008). Up to now there is no widely accepted definition of life, but identifying similar characteristics in living things can help to create tests that detect presence of life.
Adopting any of the various definitions would be inadequate as none of the explanations are robust enough. NASA conceptualized life as being both self sustaining and adhering to Darwinian explanations for evolution (Benner, 2010). Though widely accepted this definition ignores the fact that living things do not exist through a self sustaining system. Other widely accepted definitions point out that life occurs through reproduction (Popa, 2004), but this definition is also narrow as reproduction ceases at certain stages while life continues. The debate as to what really constitutes life is not irrelevant as space missions need to identify what constitutes life in their explorations. Furthermore, a precise definition is vital to understand the survival and living habits of other living things beyond the earth. There is also a need to identify the factors that make life hospitable for organisms in many habitats.
Distinguishing between living and nonliving things is the first step before a universally accepted definition can take place. In the field of biology there are no agreeable criteria on what constitutes living things though biology is the study of life (Mullen, 2002). Another potential problem of defining and designing tests for life is that living things may share characteristics with non living things, for instance metabolism is common in organisms but may also be exhibited by non living organisms. A study conducted on Mars found out that injecting the Martian soil with radioactive ingredients later led to emission of carbon dioxide (Mullen, 2002) & (Nolan, 2008). Nonetheless, the study was inconclusive as the soil had unique composition that imitated metabolic reactions (Mullen, 2002).
Origin and conceptualization of life
An understanding of the origin of life is crucial in designing tests that distinguish between life and non life forms. Historically, the earliest explanations of life looked into synthesization of amino acids as a possible explanation of life’s origin (Aubrey, 2008) & Weber (2010). However, the definition of life also depends on the purported origin, and hence the two cannot be separated from each other. In addition, these studies presupposed that life depended on the appearance of proteins as a catalyst to the beginning of life. Thus, the studies also highlighted on the role of amino acids in determining the structure of proteins and catalytic activity (Weber, 2010). However, today many studies lay emphasis on the role of the RNA in the process of replication as the first step in giving rise to life forms. On the other hand, other studies focus on the role of structures similar to the membranes that emanate from meteors, which then result in chemical reactions through energy release. The energy release is then thought to be responsible in moving pre biotic structures further away from the chemical balance (Weber, 2010).
In looking at the origin of life it is essential to highlight on the role of the origin of life and evolution which relates to the search of life beyond earth. There is a proposition that life occurs through the interaction of biological and chemical evolution that have facilitated existence in habitable places through abiotic processes (Marais & Walter, 1999). With the development of new techniques of molecular analysis it is now possible to identify environments that are suitable for microorganisms (Marais & Walter, 1999). Life on earth may have begun after earth became habitable, which gives credence to the thought this could also have taken place on other planets, because liquid water may have existed in planets including Mars and Europa for millions of years. In addition, the existence of millions of stars and galaxies beyond earth points to the presence of hospitable planets as shown in the Drake Equation which illustrates the civilizations and intelligent species in other galaxies.
The notion that chemical evolution preceded the presence of life on planet earth provides crucial parameters on which to detect life in other planets. There is growing acceptance that the origin of life relates to extraterrestrial forms which in turn relate to organic matter on earth. Though, geological processing may have erased traces of extraterrestrial forms there still are stored forms of extraterrestrial tissues in the asteroid (Sephton & Botta, 2008). Thus, in order to distinguish between life and non life forms in the outer space, it is necessary to have adequate data which facilitate decision making. This data mostly deals with what constitutes organic and inorganic carbon forms. Many meteorites have the presence of carbon compounds, but only those with organic matter show the presence of life (Sephton & Botta, 2008).
Cosmologists suggest that life occurred during the supernova period whereby there was interaction of molecules with nebular clouds that led to the emergence of DNA, amino acids, proteins and nucleotides. Over millions of years these elements blended to facilitate environments that had energy, nutrients and offered protection to organisms. There was also evolution of carbon DNA into proto cells and bacteria, the supernova also emitted metals and molten to the nebular clouds facilitating the emergence of stars and planets. Molecules formed into living organisms under the nebular planets offering safety for the organisms. The reaction of hydrogen with other gases created stars and there was also creation of matter that ejected gases and metals to nebul...