Evolution of Life on Earth

Introduction

How has life evolved on earth? How have all the organisms that we see today evolved? What does evolution mean? How has it affected our planet? These are some of the questions that come to mind when you start reading about the evolution of life on earth. So, in this tutorial, we will answer all such questions, but before we start, let us know about the meaning of evolution.

The life forms on earth that we see around are the result of the various events that took place on the earth millions of years ago. Living organisms occur from single-celled organisms to multicellular life forms. Moreover, life forms on earth have evolved due to various natural or artificial occurrences.

Life on the earth is the result of evolution, which means the development or formation of multicellular organisms from single-celled organisms, which later increased the biodiversity on the earth. Evolution is a gradual change that has taken place in the attributes of living species according to the environment required for their existence. One example is the dinosaurs that went extinct millions of years ago on earth, while some of the species survived mass extinctions and, after a while, evolved into various other species such as lizards, and birds (depending on the type of dinosaur species). These species are the result of the characteristics that developed within the bodies of dinosaurs. Therefore, evolution can be called the gradual change in the attributes and features of a species, which is the result of adaptation to situations and the environment caused due to various natural factors.

Origin of Life

The origin of life has been a topic of research for a long time. Research has been done by various scientists, and different theories have come up every time. The universe we know is infinite. The stars, moon, and sun we see are just a tiny piece of it. The universe comprises countless galaxies, and galaxies themselves constitute the vast collection of dust, clouds of gases, stars, and planets. Let us talk about our mother earth. Earth is a part of the solar system, whereas the solar system is a part of the galaxy - the Milky Way Galaxy.

What is the Big Bang Theory?

The Big Bang theory describes the beginning of the universe from a single hot and dense speckle to a cold (as compared to its initial state) and an expanded universe. This super-hot and dense point exploded with some force that created the matter, which subsequently caused the development of billions of galaxies. This universe then spread out and became cool. It even gave rise to various physical laws that rule outer space. Gases like helium and hydrogen were also formed. The gases get condensed by the effect of gravitation and form galaxies. The group of atoms and bigger atoms were born from the stars, which developed more stars. In the same way, galaxies collide and group, which creates the other stars, comets, planets, asteroids, and black holes.

The molten mass on the earth releases vapors, carbon dioxide, methane, and ammonia. The UV rays of the sun disintegrate water into hydrogen and the oxygen from which hydrogen escapes. The combination of oxygen with ammonia and methane leads to the formation of water, carbon dioxide, and others. The ozone was also formed during this period. As the temperature cooled down, the water vapors fell as rain, and this rainwater falling in the depression formed the oceans. The evidence has shown that life came on earth approximately 500 million years after the earth’s formation.

Life On Earth

Many theories have come up that say that life on earth came from outer space. Many scientists believe that Spores (units of life) transferred to earth and various other planets. It was also believed the existence of life from decayed matter.

Louis Pasteur

a French Microbiologist, illustrated that life can only arise from living organisms. Non-living things are not responsible for the creation of life on earth.

He did the experiment in which he put the pieces of meat broth in different S-shaped flasks and then boiled the broth to kill the microorganisms present in the broth. After that, he broke off the necks of some of the flasks while keeping the other flasks as they were. In this experiment, it was observed that dust particles settled on the broth present in the flasks with the broken neck whereas dust particles settled on the neck of the remaining flasks (which were not broken).

The flasks with the broken necks become cloudy, which shows the presence of microbial life.

It was observed that life can not originate from non-living organisms. On the contrary, his experiment failed to prove the origin of spontaneous generation.

Later on, Oparin of Russia and Haldane of England came up with the observation that already existing lifeless organic molecules (example - protein, ribonucleic acid, etc.) and that chemical progression is responsible for the formation of living organisms from non-living organisms

Another experiment was conducted by an American scientist - S.L. Miller, in 1953. He created the earth-like atmosphere on a laboratory scale. The earth-like conditions mean oxygen, high temperatures, volcanic storms, etc.

Miller circulated the high-frequency electric spark in a flask that was filled with methane, hydrogen, and ammonia. Water vapors were created by boiling small quantities of water. With this experiment and other similar kinds of experiments, he concluded the formation of amino acids, fats, sugars, and nitrogenous bases. This experiment suggests that similar events must have occurred in space, which resulted in the creation of living forms from naturally occurring chemical reactions.

Conclusion

The universe is limitless and earth is just a small part of it. The Big Bang theory explains how the hot and dense freckle developed into a huge planet with variations of life forms on it. Scientists from different laboratories conducted experiments to observe how life originated on earth. Louis Pasteur illustrated that life can only arise from living organisms. Non-living things are not responsible for the creation of life on earth. Another experiment was conducted by an American scientist - S.L. Miller. He created the earth-like atmosphere on a laboratory scale. The earth-like conditions mean oxygen, high temperatures, volcanic storms, etc. His experiment suggests that life on earth occurred from living forms and naturally occurring chemical reactions.

FAQs

Qns 1. What do you mean by the term evolution of life?

Ans Evolution can be called the gradual change in the attributes and features of a species, which is the result of adaptation to situations and the environment caused due to various natural factors.

Qns 2. Describe Big Bang Theory.

Ans The Big Bang theory describes the beginning of the universe from a single hot and dense speckle to a cold (as compared to its initial state) and an expanded universe. This super-hot and dense point exploded with some force that created the matter, which subsequently caused the development of billions of galaxies.

Qns 3. Who experimented to prove that life can only be originated from existing living forms?

Ans Louis Pasteur, a French Microbiologist, illustrated that life can only arise from living organisms. Non-living things are not responsible for the creation of life on earth.

Qns 4. What was S.L. Miller's experiment?

Ans S.L. Miller created the earth-like atmosphere on a laboratory scale. The earth-like conditions mean oxygen, high temperatures, volcanic storms, etc.

Miller circulated the high-frequency electric spark in a flask that was filled with methane, hydrogen, and ammonia. Water vapors were created by boiling small quantities of water. With this experiment and other similar kinds of experiments, he concluded the formation of amino acids, fats, sugars, and nitrogenous

bases. This experiment suggests that similar events must have occurred in space, which resulted in the creation of living forms from naturally occurring chemical reactions.