We begin discussion of what sustains life on Earth with a brief discussion of the origin of life on our planet. In the absence of belief in supernatural creation events, the question of how life began has baffled naturalistic scientists for centuries. Those scientists seek to describe and explain (1) the conditions on our planet under which life arose and (2) the scenario of the apparently sudden appearance of life once the proper conditions appeared.
Planetary conditions of four billion years ago are fairly easy to describe. At the time, earth was a water world. A thick layer of clouds surrounded a water encircled Earth. Light from the sun did not yet illuminate the surface. Earth’s water began to absorb volcanic gases released by tectonic activity. The oceans dissolved minerals from the solid crust of the earth. It is certain that earth’s water was never chemically pure—i. e., H2O without any dissolved substances. The dissolved minerals became food for the microbial life which appeared suddenly in the water world—morphologically simple but biochemically complex microbes. Theologians and theistic scientists see the wholesale arrival of microbes such as bacteria as a startling divine creation event on Planet Earth.
Virtually all of our life activities would cease without microbes. They are ever present in and on our bodies, in the ground we walk on, and in the water and food we consume. Our food would not grow, our bodies could not digest food, and our garbage would not decay. Living things on our planet would not survive without the sustaining action of microbes. In short, microbes supply the food on which all life depends.
Perhaps we do not acknowledge bacterial activity as the original source of life sustaining food. We must revert to our knowledge of the bacteria of the geologically early earth. Their food-producing functions still continue in our day. Early and contemporary earth bacteria are categorized as autotrophs or heterotrophs. Autotrophs make food through processes such as photosynthesis while heterotrophs live off other organisms.
Quoting from Todar’s Online Textbook of Microbiology: “The earth is a closed system with limited amounts of certain elements in forms that are utilized by cells.These elements are generally acted upon first by microbes to assimilate them into living matter. The total biomass of microbial cells in the biosphere, their metabolic diversity, and their persistence in all habitats that support life, guarantees that microbes will play crucial roles in the transformation and recycling of these elements among all forms of life…..The list of examples of microbial involvement in the cycles of elements that make up living systems is endless, and probably every microbe in the web is involved in an intimate and unique way.” Early earth bacteria are the original food producers.
Our conversation is far removed from the expected topics of the food needs of our contemporary human population. The science of agricultural food production and consumerism would dominate that conversation. At each level of discussion, however, we give glory to the Creator of all life from the original bacterial life on primordial Earth to the complexity of modern Earth life—millions of unique species dominated by one species—humanity over seven billion strong.