There was a time when things started rolling on with advent of photosynthesis by cyano-bacteria or green algae which began preparing its food from carbon dioxide and water which were the only substances available in plenty. They paved the way for introduction of oxygen into the atmosphere and for beginning of life dependent on oxygen.
In fact, both the products made by photosynthesis namely sugar and oxygen are used by animals including humans for sustaining their life. We animals are thus the species who learned to make use of the leg work of others to their own advantage. Of course, in today’s world, human beings who do this are termed smarter than the others.
So what the plants and algae used for making their food is being recycled back to the atmosphere in the form of green house gases. Plants use CO2 and H2O and took energy from the Sun to convert these to sugars and animals extract that energy from the food synthesized by plants and algae and return the CO2 and H2O back to the atmosphere.
CO2 is in fact one of the end products of burning the fossil fuels like coal and petroleum which are the preserved forms of energy of Sun due to being buried away from the reach of oxygen. Since all industrial activities use extensively these fuels, levels of CO2 are rising in the atmosphere to alarming levels.
Trees breathe the CO2 through the stomatal pores present in their leaves. They also lose the water through these pores during the day. They are smart enough to adjust the size of their leaves so as to optimize the intake of CO2 and loss of H2O for proper growth.
One such tree was born in 1948 in a isolated place on the edge of a pit 30 kilometers from Dutch city called Eindhoven. By 1990 it was a big majestic tree as most of the Birch family trees are. Scientists from the laboratory of Paleo-botany and Palynology named it fondly “Big Betty”.
During each autumn, the tree will shed a carpet of dry leaves into the pit. So layer after layer is deposited inside the pit. But scientists noticed a peculiar thing about the leave size. Each year the leave size began becoming smaller thus reducing the stomatal index. This was due to the fact that as levels of CO2 rose, the tree needed fewer number of stomata to inhale the same quantity as required and thus avoided the undue loss of moisture from the leaves. In fact when the levels of CO2 were plotted against the stomatal indices of leaves over these years, they matched the patterns of levels of CO2 variations. So the stomatal index was used to calibrate and interpolate the results to guess the levels of CO2 in the past.
Scientists speculate that all the fundamental particles were created from the energy immediately after the Big Bang event in which Universe was formed. Then these atoms combined in different permutations and combinations and molecules were born. Context of immediately in the cosmic events is not similar to the usual terms with which define our world. It may be millions of years.
Earth was formed but its climate was not like the present day. There was no life except one algae namely “Blue Algae” known in the scientific language as “Cyanobacteria” where “Cyano” stands for blue color. It thrived in the water which occupied 70% surface of the Earth. All around in the atmosphere was carbondioxide and metals existed in the solution form because there was no oxygen to react with them and precipitate them as ores. Iron was the most abundant of them. So this was the scene about 3.5 billions of years ago.
How did these small living beings sustain themselves? Where from did they get the energy? .
They developed the photosynthesis and harvested the energy of Sun. They also did much of the chemistry which resulted in critically changing the composition of gases in the atmosphere. They learned to break the water molecules into hydrogen and oxygen. They then used the hydrogen along with carbon dioxide to make carbohydrates which are the store house of energy. The oxygen gas which was generated was very reactive and reacted with the metal ions especially iron species and got fixed up and ores were formed. This went on for millions of years. Iron acted as a perfect sink for oxygen which was poison for these bacteria themselves because they thrived in the anaerobic conditions.
But a stage reached when no more free iron ions were available. So the concentration of oxygen began building up in the atmosphere and setting a stage in which the new species of life which use oxygen for breathing to evolve. The life started in the real earnest. The oxygen content stabilized at about 20% by volume in the air. Carbon dioxide has very small percentage. So these humble microbes were responsible for the life as we see today on this Earth.
The algae learned to live with the existing conditions.
How big is the cyanobacteria? It has been estimated that its diameter is about 2 microns if we consider it as a sphere which it is not. But for the sake of simplicity and bring home the point as is done in all the scientific inquiry let us assume that. Such a small size !! But is it really small in comparison to the smaller things nature can go to. Let us compare it to the size of carbon atom. If we calculate the volume of bacteria and volume of carbon atom, and calculate how many atoms of carbon can fit into the bacteria, you shall be surprised that a mind boggling 1000000000000 atoms is the answer. You are in for more surprise if you go down to fundamental particles like electrons and leptons.
So this is the scale at which the machinery of the Nature works. On one side are the atomic sized particles and on the other are gigantic stars. But one thing is sure that at the base of everything are the fundamental particles. It is also a fact that things behave very differently on the different scale levels. Electrons can behave as particles under one set of conditions and as a wave in the diffraction experiments. Or they may be behaving as they are but with our existing knowledge we try to explain the things the way which give reasonable answers.
So let us salute to the “Cyanobacteria” to create favorable conditions for the existing worlds to forms and initiation of the diverse kinds of species on this Earth.
I am a molecule of water. Hydrogen and Oxygen are two elements which combine in the ratio of 2 to 1 to create me. I have abundant siblings on the earth. In fact we make up for about 70% of the earth. I am so small that I can enter into smallest of spaces. My birth place is in the space. We all are so identical that it is impossible to label us with names. We all have only one name and that is water. there are species called homo sapiens After birth I along with my other brothers began living in a place which people started calling the seas. In the beginning we all lived in one place but many upheavals separated us and we were divided into many parts.
We are always in the ceaseless state of movement. Never had time to rest. We chase each other, collide with each other and collide with surroundings. Some of us move and dance faster than others. When the agile ones get tired, they slow down and hand over the baton to sluggards who in turn become agile. But we are bound to each other. But when the Sun is angry and it is hot, some of us are thrown out from the sea and fly up and up. Then we float aimlessly in the atmosphere. We wander from here and there. But we again come together at places which are cool such as above the mountains and rich vegetation. We join one another so tightly that we cannot remain afloat. We begin to fall towards earth.
So of us fall on the mountains where temperatures are so low that we become hibernated and enter a deeper and longer sleep. Others fall directly on the earth where they flow collectively as one body and travels from high altitudes to low altitudes. Some of us are very curious and collect inside the depression and become confined there for very long periods. Other more adventurous even penetrate the earth and go deep inside it and remain there for thousands of years. During our journey on the land we take with us members of other communities which disintegrate inside us into their individual entities. Some of us joined on the way with others become a mammoth creature called the river and flow towards our home at sea. It can take us 2 to 6 months time for reaching back.
Our brothers in the confined places called lakes and ponds have to wait much much longer to reach home. When Sun smiles benignly on them, some of us again escape into the atmosphere and if lucky go back either falling directly into the sea or falling again on the earth and joining the other which have already begun their journey towards home in the form of river.