Origin of Life on Earth

Introduction

Origin of life is one of the most fundamental yet least understandable topics. Various scientific and philosophical problems have been growing around this topic, and extra-terrestrial life is also involved. There are lots of hypotheses present for the origin of life, but here we are listing them one of four categories: 

The origin of life can be termed a supernatural event that cannot be explained in physics, chemistry, or any other science. Life can arise from even non-living particles spontaneously in a very short period.

Life is coeternal, and there is no way to trace its beginning, so life arrived or started with the Earth’s origin.

Through a series of Progressive chemical reactions, life started growing on the Earth. Such reactions may also require one or more highly chemical events.

Origin of Life on Earth

The first living form, dated about 3.22 billion years ago, marking Earth’s existence is the blue-green algae Cyanobacteria. The existence of this bacteria is proven by the fossils that are being found in the rock around 3500 million years old in Western Australia.

Although Cyanobacteria is commonly referred to as algae, it is not an alga. These are prokaryotic life forms for which cells don’t have organelles and distinct nuclei. This character distinguishes this form of life from bacteria and archaea. Bacteria (and archaea) are quite strong and hard creatures. They can adapt and sustain themselves in hot, cold, salty, acidic, and alkaline environments. But sometimes, the microbes get a bad name due to their disease-causing nature.

One of the earliest and simplest living forms that fed upon carbon compounds from Earth’s oceans is Prokaryotes. Cyanobacteria move a step ahead; they use water for photosynthesis and release oxygen by-products. Oxygen gets accumulated in the atmosphere and helps in the evolution of oxygen-metabolising organisms.

Eukaryotic cells are being formed by a symbiotic relationship between two independent prokaryotic bacteria. Single bacteria engulf another one, and the smaller cell exists inside the parent one, which is beneficial for both living forms. Thus, they have marked themselves as the more advanced eukaryotic cell in this manner.

The evolution of eukaryotic cells has significantly been a milestone in the history of the origin of life on Earth.

Origin and Evolution of Life

Chemosynthetic Theory of Origin of Life

As per A.I. Oparin, in the distant past, life originated on the earth through some series of combinations of chemical substances, which all happened in water.

About 5 billion years ago, the Earth originated from hot gases and vapours of many chemicals. These gradually cooled down, and a solid crust formed. There lies no free oxygen in the early atmosphere, but a large part of oxygen is formed by Ammonia, Water vapour, Methane, and Hydrogen. The water bodies are created in the earth for the heavy rain that falls on the earth’s surface. Methane and ammonia get dissolved in the water bodies from the atmosphere. Thus, various new chemical reactions occur from this water, and this provides a new compound also known as Amino acids, which recombine and produce biomolecules of life like proteins and nucleic acids.

Evolution

The change in the biological hereditary and characteristics of organisms because of the change in genetics and change in environment. There are four types of evolution: divergent evolution, convergent evolution, parallel evolution and coevolution. The mechanisms through which the characteristic evolution happens in organisms are mutation, genetic drift, gene flow, non-random mating, population speciation and natural selection. The gradual change of simple ancestry into a complex form of the organism is termed Evolution throughout geological time.

There lies various evidence which supports the organic evolution of living form they are:

• Morphological evidence
• Embryological evidence
• Paleontological evidence
• Molecular evidence

For Morphological evidence, we are generally focused on Homologous and analogous organs, vestigial organs, and Connecting links.

Darwin’s Theory of Evolution

Darwin was a very fine experimentalist and observer, he observed flowers and animals and their pattern of existence. As time goes Darwin’s sources of evidence have become more comprehensive and throws recent genetic biochemistry, physiology, ecology, animal behaviour, and Molecular Biology type of studies to evolve. 

The evidence of Evolution charts generally depends upon an organism’s genetic variation, which helps them challenge and tackle natural selection. The primary evidence showing evolution throughout the years depends on the critical points of anatomy, Molecular Biology, biography, fossils, and direct observation.

Fossils 

The most important physical evidence which allows the study of evidence of evolution is called the fossil. Fossils are obtained by digging soil, they are preserved remains of organisms that lived past geological age. For example bones, shells, stones imprints, oil, coal and DNA all are evident proof of the evolution of the earth through time.

Conclusion 

The community clay also helps sustain the origin of life. The main role of DNA is to store information or genetic information by organising themselves. The deep-sea vents also suggest that life has begun at the deepest depths of the sea containing hydrothermal vents, which are hydrogen-rich. Highway some scientists also mention in India’s theory that life did not begin on the earth at all but in space, also called panspermia.