show that some animals were mobile before the Cambrian Explosion. Sponges were probably the but they were immobile except for their flagella drawing water through them, which carried food and oxygen in and waste out. The first creatures that we would recognize as animals were probably worms crawling atop ocean sediments. As lowly as the worm might seem, it would have needed muscles, bilateral symmetry, a circulatory and digestive/excretory system, and a nervous system run by a brain; that distant ancestor probably possessed . Some early worms may have even had rudimentary eyes. And of possibly eonic importance, worms probably made the first poop. The evolution of may have been a seminal event in the organic carbon burial process. Sponges may have also been largely responsible for initially removing oceanic carbon, which helped increase atmospheric oxygen and helped ventilate the oceans. Until then, organic carbon from dead life forms would not have settled to the ocean floor, but would have floated in the water column and been recycled by other life forms. Although the hypothesis , feces sinking to the ocean floor may have been how life’s burial of carbon began, as well as robbing sulfate-reducing bacteria in the water column of their nutrients and thus enabling oceanic waters to remain oxygenated. Ediacaran fauna did not burrow into ocean sediments, but deep burrowing was characteristic of Cambrian sediments. There is debate today whether Cambrian burrowing was a of oxygenating the ocean floor.
About 2.7 bya, dissolved iron in anoxic oceans seems to have begun reacting with oxygen at the surface, generated by cyanobacteria. The dissolved iron was oxidized from a soluble form to an insoluble one, which then precipitated out of the oceans in those vivid red (the color of rust) layers that we see today and are called ("BIFs"), which became an oxygen sink and kept atmospheric oxygen low. The GOE is widely accepted to have created almost all of the BIFs, but it is not the only BIF-formation hypothesis and there is a great deal of controversy, but life processes are generally considered to be primarily responsible for forming the BIFs. Most iron in the crust is bound in silicates and carbonates, and it takes a great deal of energy to extract the iron from those minerals; the oxides that comprise BIFs are much less energy-intensive to refine, as the iron is so concentrated. Far less ore needs to be melted to get an equivalent amount of iron. BIFs are the source of virtually all iron ore that humans have mined. Life processes almost certainly performed the initial work of refining iron, and humans easily finished the job billions of years later. Copper was not refined by life processes, and copper ore takes twice as much energy to refine as iron ore does.
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At this juncture, I will ask my readers to perform an exercise that I first saw described by Peak Oil advocate , which is to lay aside data and graphs and just think about how energy makes everything in our daily lives possible. Think about your food, water, mode of transportation, and materials that comprise your home and possessions, and think of the role that energy played in providing them. Think about the energy that you use each day in powering your home and in your transportation, even if it is just walking. Then imagine running out of energy. When you flipped on a light switch, nothing happened. When you turned on the tap, no water came out. Your refrigerator stopped working, food deliveries to your community ceased, and no electricity, oil, gas, coal, or even wind or water power was available. Everything in your life would come to a sudden halt. When people have tried to demote energy below spirituality, social relations, or even made it irrelevant to economics, my question is for them to see what they can forego the longest: prayer/meditation, social interaction, sex, or energy. The fossil fuels burned to power industrial civilization provide several hundred energy slaves for each American and no less than hundreds per person in every industrialized nation. All that those energy-leveraged humans do is direct the energy, like holding the reins of a gigantic beast that each person rides each day. Airline pilots half-joke that they begin their workday by strapping jet airliners to their waists. Without that energy to direct in the myriad ways that industrialized humans use it, modern civilization would come to an abrupt end.