How did the oxygen come about?
Life had taken root on earth and was beginning to spread. These were anaerobic microbes. Three billion years ago, cyanobacteria emerged from them. Their source of energy was not the volcanic heat of the earth. They derived their energy from the sun. Life began with photosynthesis. There were many types. Each caught a different wavelength from the sun. The shores and waves of that time were like the colors of an artist’s paintbrush. Purple, green, red. They also contained cyanobacteria (Blue Green Algae). What was special about them was that they took energy from the sun, but that they peeled electrons from the water with the help of sunlight. Electrons perform chemical reactions. Instead of the rare sulfur, cyanobacteria could now draw energy from the most common molecules on Earth. Their production was very high because of this.
The process of converting the sun into useful energy begins with chlorophyll. A green molecule that acts like an antenna and absorbs light from the sky. After that, biochemistry is a bit more complex, but it’s basically a chemical reaction from the sun. And water is converted into hydrogen and oxygen. Some of them combine with carbon dioxide to form glucose-like sugars.
This extra cost of chemistry saves some extra oxygen. We like free oxygen today, but it was toxic to life at that time. Ultraviolet rays break down oxygen molecules to form free radicals. It chewed and tore the DNA. Free oxygen destroys the ability of nitrogen-fixing bacteria to break down the iron atom in this enzyme. Oxygen was a dangerous enemy of terrestrial life at that time.
Fortunately for these fragile microbes, oxygen was not initially collected. It often reacted with objects, whether in the air or in the water. There was a large amount of iron in the water. This oxygen began to rust the iron. These tiny particles of rust began to accumulate in the ocean floor and turned them red. We still see it in every ancient seabed. Ninety percent of the world’s iron reserves are similar, and that’s the work of these microbes.
As long as this dissolved iron remained, oxygen did not pollute the atmosphere. Year after year, from time to time, cyanobacteria kept spreading, kept doing the same thing, iron kept running out. Things even started to get worse for them. Free oxygen began to accumulate in the ocean. Life began to kill. Then it began to spread in the air. These were toxic clouds for these microbes. There has never been such a great danger to life. Every branch of life faced death.
Then life began to face this danger. Some made external members. Some shielded their inner walls to protect the enzyme that fixes nitrogen. There were a few others who did nothing. Their cellular machinery began to use this gas for energy. He used his explosive power for his energy. It’s as if someone has been attacked by chemical weapons and they have used this poisonous gas. Incredibly amazing, but these were the special bacteria that did the amazing thing.
Today, we and almost all life on earth are dependent on these germs because they have made life possible. Multicellular organisms became possible. All cells contain tiny mitochondria caused by these untouched germs. These mitochondria make energy possible through oxygen. It is taught in school that living things need oxygen to survive, but this is not usually the case. The short trick is that the mitochondria use oxygen to break down sugars like glucose. Without it, very little energy can be extracted from these sugars. But it is the mitochondria that absorb energy that do this with the help of oxygen. Without it, our energy battery would run out and we would die in a matter of seconds.
Remember that plants also breathe the oxygen they need for growth and reproduction.
Oxygen changed not only life but also the earth. Free oxygen attacks greenhouse gases. Eliminated methane-like gases. This caused the earth’s temperature to drop. The ground was covered with snow. Glaciers also came to the equator. Two-thirds of the earth’s minerals are formed only in the presence of oxygen. Among them were many gems and jewels. Rubies and sapphires formed from this oxygen attack. Many minerals cannot survive in the presence of oxygen. That is, these ancient minerals were destroyed by oxygen. Stones also thrive or disappear in the presence of gases. Oxygen was a message of life for many of them, a message of death for many.
Today, oxygen is 21 percent of the atmosphere and remains at that level. Some of it comes from plants and some from microbes. Two billion three hundred million years ago today, when iron was depleted from the oceans, oxygen was one in a trillion molecules in the atmosphere. In the next few hundred million years, it had reached one in five hundred molecules. Such a rapid increase in a short period of time had almost wiped out life. One billion eight hundred million years ago this level had reached a level when minerals on earth began to suck it up. For the next one billion years, it remained at the same level as the minerals saturated and then began to grow. Plants and animals began to appear in the fossil record at that time. Because of this energy, the creatures that could run away could hunt, reproduce sexually and kill.
After that the oxygen level kept going up and down between fifteen and thirty five percent. It had its effects. When it was high, it was so high that a small flame could ignite a large fire, and when it was low, it was so low that it would be difficult to light something even for falling lightning or volcanoes. Today, if a person wants to go back in time by making a time machine, then this is the first stage in the history of the earth when he will not step out of the time machine and die. With less than 17% oxygen, the ability to think begins to be affected and it becomes difficult to walk.
Insects benefited the most from the increased oxygen levels. Insects do not have lungs. They carry oxygen in through the pores of their cells. Geometry shows that as they increase in size, the surface area increases more slowly than the volume. Because of this, the worms cannot grow very large, otherwise they will die due to lack of oxygen. That is why today’s insects are so small. When the oxygen level reached thirty-five percent, it was easy for them to grow up. If our friends go to the time machine 300 million years ago, they will find one-yard-long wings and pigeon-sized flies and tire-sized spiders. These were the feats of oxygen.
At current oxygen levels, we need one breath in four seconds, twenty thousand a day. This is the oxygen that all life today shares. If plants and oxygen-producing bacteria stop making it, in a thousand years all oxygen-dependent life will be gone from the earth. In a million parts of how long it has taken them to become. But microbes and plants do this every day. This beautiful balance of giving and taking between different forms of life is maintained. Plants take in carbon dioxide and water to produce sugar and oxygen, and animals use these sugars and oxygen to make carbon dioxide and water.
This beautiful balance of yin and yang is maintained. No subtle auditor can find fault with this delicate balance of chemical accounting.
In physics you will study symmetry and the beauty of nature. But this symmetry of oxygen and carbon dioxide is more impressive. Because it has taken so long to get here and so many things have contributed to it. There are so many things that can go wrong, but they don’t. Banyan trees, chirping birds, cyanobacteria and we. Everyone is a partner in this balance.