Others abandoned the surface environments they had polluted so thoroughly with their oxygen waste. They flourish in environments without oxygen like marshes, acid soils, or frigid lake bottoms. Trouble for the procaryotes! Most went extinct. Oxygen began to accumulate in the atmosphere and ocean. But the ocean waters back then contained much dissolved iron, which sopped up the oxygen they released, making iron oxide – rust – that settled down to the seafloor. Today, these ancient “banded iron” deposits are mined for steel.Īround 2.3 billion years ago all the dissolved oceanic iron was used up. No wonder cyanobacteria oxygenated the world, even if it took them almost a billion years.Īncient cyanobacteria were too crude to handle oxygen, for them a deadly byproduct. But they reproduce quickly! If even only one splits into twins that also split just days later, its descendants multiply astronomically. Procaryotes evolve slowly because they can’t exchange genetic material. Cyanobacteria are still with us, blooming and rotting spectacularly in our fertilizer-laden runoff. Importantly, photosynthesis releases oxygen gas as a byproduct. They use water as fuel, splitting it with sunlight and combining it with carbon dioxide into fats and sugars.
The other procaryotes are all the other bacteria, including Cyanobacteria that harvest solar energy by photosynthesis. They continue to thrive in the harshest of environments, like volcanic vents and acidic soils. The first of all life forms are procaryotes called Archaea (“Ancients”). The first living stuffs may have organized themselves on the microscopic crystal structures of clay minerals.Ĭrude living forms arose about 3.5 billion years ago. No larger than 1- millionths of a meter (microns), these cells are called “procaryotes” – “before kernels” or “before nuclei” – because they came long before the much more sophisticated “eucaryote,” “good nuclei” cells of more advanced life, including ours.Įvery procaryote has a sloppy “nucleolus,” like a nucleus, but no membrane separates it from the rest of the body. Too primitive for sex, procaryotes reproduce by simply splitting themselves in two. Perhaps at underwater volcanoes, energetic places with complicated chemistries. How life began remains unclear. A likely place would be under enough ocean water to filter out the X- and ultraviolet rays. Ozone molecules are three oxygen atoms bonded together no oxygen, no ozone in Earth’s atmosphere to intercept the Sun’s X-rays and ultraviolet waves fiercely irradiating Earth’s surface. How life made and keeps Earth livableĪlthough newborn Earth wasn’t frozen over, it was too deadly for life. Atmospheric oxygen would come much later. Its volcanism sweats out water molecules, the runaway Greenhouse heat rips them apart into hydrogen that escapes into space, and oxygen that forms solid rust and rock. Lifeless, Venus continues to accumulate its massive CO 2 atmosphere. Gaia had taken over, and has molded and maintained the living planet ever since. How? By combining it with calcium dissolved in the oceans to make calcium carbonate for their shells, which slowly accumulated as limestone. And some of their tissues were slowly buried underground as oil, methane, and later, coal. Answer: living things emerged and moderated the Greenhouse Effect by removing CO 2 from the air and ocean.
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