Edible Universe

April 27, 2011

After Areios unthawed from a 130-million-yer long period of worldwide glaciations, the planet looked remarkably different from before the deep freeze. The atmosphere was made up of reduced gases like water vapor carbon dioxide, hydrogen sulfide and methane, and carbonyl sufide. Gases like water vapor, carbon dioxide, carbonyl sulfide and methane are powerful greenhouse gases that raise the average temperature of the planet. On Earth, an excess of these gases generated by human industry are widely believed to cause destabilizing climate change on Earth. On a planet like Areios, this increase in greenhouse gases is a boon because it melted the ice that straddled the tropical regions of the world and caused sea levels to rise, washing organic salts and other chemicals locked in the continental crust into the sea, making a frothy brew of organic chemistry that would form the basis for the earliest life.

Deep at the bottom of the ocean, there are volcanic vents that eject boiling water laced with metals; on Earth these environments are heavily populated with life. Meter-long tubeworms powered off of bacteria in their guts that eat the dissolved gases in the water. Translucent crabs and squids feed off of the see-through krill that are the basis of this underwater ecosystem. Researchers believe that the bacteria found in these vents are among the oldest known organisms on Earth. Similarly, these vents are the wellspring for the first life on Areios. Iron-bearing minerals at the bottom of the ocean serve as catalyst for complex organic molecules to form. Over time as a primitive form of natural selection takes place the more robust molecules that replicate with greater efficiency win out over organisms that can’t replicate fast enough or fall apart too easily. And over time, those molecules that could replicate the best would dominate the environment. It’s easy to imagine that the first life forms on earth were bare-bones, single-celled proto-cells that could replicate and do not much else.

Over time, those that developed a more robust metabolism could survive times when the organic molecules that they fed on were scarce. And as natural selection kept on, the metabolisms of these early cells became more and more eclectic, with many different metabolic pathways being developed by their forms to exploit the energy around them. This allowed for greater biodiversity and minimized competition for the same resources. The early biology on Areios as well as on Earth formed these microbial mats; an entire ecosystem was enclosed in a single patch of pond scum, with some creatures emitting gases like methane or hydrogen sulfide and other creatures that could exploit these waste for their own metabolism, transforming that hydrogen sulfide into sulfur granules of sulfuric acid and breaking that methane down into hydrogen gas that bubbled out of seas.

At first the earliest life was confined to a single area, but pressure for resources like the organic molecules that served as food, life forms began to spread out around the globe, filling up new unexplored niches and evolving to meet the new conditions. Eventually, every niche around the world was filled up and there was nowhere else for these life forms to head to. And from that point on, the competition for resources intensified and the less resilient creatures were muscled out of their niches. In perhaps the greatest phenomena of the time, predation arrived on Areios soon after the niches of the world were taken. Bigger organisms no longer had to engulf free-floating molecules in order to feed; they could engulf their free-floating cousins, too. This is entirely because of biological compatibility; organisms that ingest free-floating molecules incorporate nutrients into their metabolism and other organisms with the right cellular machinery can eat those cells and gain their nutrients from the primary producer. This was one of the first major events in the history of life on Areios and predation will lead to yet another milestone in the history of life; the appearance of eukaryotic cells from what is called endosymbiosis. But more on that later…

Early life may have formed in hydrothermal vent communities.

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