Life’s Evolution: Energy Conversion and Survival Strategies

Life has infiltrated the solid, liquid, and gaseous surface of this planet. Iron, sulfur, phosphorus, nitrogen, oxygen, hydrogen, manganese, arsenic, and other elements involved in microbial metabolism are under life’s influence or control. As far down as it has been feasible to dig, live bacterial cells have been found inside solid rock.

We, like all living beings, perpetuate ourselves and our communities but never with complete efficiency or total recycling. We, from the cells within us to the organizations in which we as “individuals” function, are semi-independent thermodynamic systems.

Maximum power principles state that those organisms or ecosystems that can most efficiently convert energy into biomass (including seeds and spores) enjoy an evolutionary advantage over their neighbors. Individuals and populations that fail to maintain or expand their systems’ energy flow head for the exits of extinction.

When organisms through their own evolution come upon a new energy source, there may be a period of danger associated with experimentation and rapid spread. The new energy forms, useful as they are, have not yet been integrated into stable modes of survival. This situation appears to be the case with human beings presently.

Energy creates as well as it destroys. Plant evolution depends in part upon spontaneous mutations, but the shape of a leaf or a flower is not arbitrary: the growth and evolution of plants is in the direction of capturing ever more energy from incoming sunlight. Some albino vines do not use sunlight directly in photosynthesis but have suckers (haustoria) that let them exploit the green surfaces of plants that do.

We should not be cavalier about locating intelligence only in organisms with brains. Awareness and intelligence seem to exist in networked collectives of cells of many kinds. The common view of intelligence is an-thropocentric, even as some standardized intelligence tests are ethnocen-tric. Brainless bacteria swim toward sugar and light; their autonomous actions are purposeful. The networking of ecosystem interactants makes it hard to say who is using whom, who is smarter, who is more dominant: organisms, including humans, are involved in intelligent ecosystems with many sensitive indispensable agents.

Scientific dates for the oldest bacteria are now nearly coincident with Earth’s cooling to the point where it had a solid crust. This suggests the earliest life-forms were extremely tough heat-resistant “thermophiles” and “extremophiles” tolerant of extreme conditions, in biological jargon.

Life was already thriving on Earth when the moon, whose rocks have been reliably dated and which had no protective atmosphere, was being heavily bombarded and cratered by meteorites from space. Life’s survival from this early violent period suggests that it was tough from the start, somehow protected, or, more probably, both.

The kind of energy required for organisms to maintain their bodies, their metabolism, is strictly limited. The list includes light (photoautotrophy), organic chemical energy (heterotrophy), and a very limited number of inorganic energy-yielding chemical reactions (sulfide to sulfur or sulfate, methane to carbon dioxide, ammonia to oxidized nitrogen compounds, hydrogen to water). Heat, a thermodynamic waste product roughly equivalent to en-tropy, is not on the list. Organisms also need food, which forms the stuff of their bodies. Energy gets used up; food is transformed into matter and materials of the body. One of the reasons we tend to be confused about these things is that we animals don’t distinguish food from energy in our metabolism. In animals the source of energy and food is the same (sugars and other carbohydrates, amino acids, and proteins). In plants, however, the sources of energy and food are entirely different; sunlight is the energy source and carbon dioxide, chemically converted to sugars and other ma-terials, is the source of food. Finally, if your food source is carbon dioxide, you need a source of electrons (hydrogen atoms) to reduce the carbon to cell material.

While ecosystems by definition recycle most of their elements within themselves, the span of ecosystem recycling can be quite wide, and ecosystems can overlap. Life’s nested cycling networks scale from cell metabolism to animals replacing cells in their tissues to the growing, living super ecosystem we call the biosphere. One would also expect any extraterrestrial biospheres to be recycling nonequilibrium worlds exhibiting growth, and trends toward increased biodiversity and metabolic efficiency.

Ecosystems represent biologically stable patterns across many scales of a space-time hierarchy. Climax systems are vulnerable to rapid change. The systems are often at an unstable point, like dry wood load and biomass in a dry forest.

A very small perturbation, a spark from metal to rock of a passing horse-shoe, can reset the successional clock within seconds. Nonlinear dynamics and catastrophic events are common throughout these biological systems.

Source : Into the Cool: Energy Flow, Thermodynamics, and Life by Eric D. Schneider, Dorion Sagan

Goodreads : https://www.goodreads.com/book/show/52737.Into_the_Cool

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