Origin of Life
The earth is the most beautiful planet among all known celestial bodies, since a variety of flora and fauna has painted it in many glorious colours. Countless animals of diverse shapes and sizes thrive here. Long ago, the human race—the most intelligent species on the earth—lived in a way similar to other animals. Humans spent their entire intelligence, time and energy in fulfilling their basic needs of food, sex and shelter.
After the beginning of cultivation and domestication, priests found opportunities to study animals closely and noticed that each female produced its progeny. After such study, they had another question: who gave birth to the first female? They spent countless hours discussing whether a hen or an egg came first. Priests of almost all ancient civilizations pondered over the origin of life on the earth and built their own theories to explain it. Around four thousand years ago, several priests documented their theories in religious scriptures.
For example, the ancient holy texts of Mesopotamia mention that the sun built the sky and the earth from the dead body of the devil, Tiamet. They also supposed that the sun created humans for its worship.
Ancient Egyptians believed that the sun rose from the depths of the ocean, built dry land and then created all creatures. Hindus, from antiquity to date, suppose that Lord Brahma created life. Ancient Jewish priests formulated the theory of special creation; Christians and Muslims also believe this theory. This is the most elaborate, interesting and widely accepted belief today; it has been discussed in an earlier chapter on Judaism.
The origin of life on the earth has been a fascinating topic of research for philosophers and biologists as well. Aristotle, in 330 BCE, advocated that life originated spontaneously from non-living organic matter. He believed that worms, wasps, mites and insects had originated from rotting dung, and this belief continued until the early modern ages. For instance, in 1640 CE, eminent physician, Van Helmont claimed to create a mouse in twenty-one days from his shirt. He marinated the sweat-soaked shirt in wheat flour and kept it in a dark room during those days.
In 1862 CE, Louis Pasteur discarded the theory of spontaneous generation. He poured a nutritive soup in a glass flask, boiled it to kill all living organisms in it and closed it with an airtight lid. The sterilized soup in the airtight container remained unchanged and did not develop a putrid smell even after several days. Later, Pasteur left the flask open; within a few days, the soup developed a foul smell. The bacteria present in the air entered the soup and putrefied it. He concluded that only pre-existing creatures could produce their progeny. The question of the origin of life, however, remained unanswered.
Although most religious theories about the origin of life were not logical, people continued to believe them for a very long period. In 1809 CE, a French naturalist, Jean-Bapiste Lamarck began to visualize the evolution of animals. Lamarck explained his thought through a few examples. He propounded that millions of years ago, the average height of giraffes had been less than what it is now. Their herd comprised members of variable heights. In adverse weather conditions, each group found it difficult to find grass in the forest; only the taller ones could reach the leaves of higher trees. Consequently, they thrived and reproduced more successfully than the shorter ones. This led to an increase in the progeny of taller ones. Gradually, after thousands of generations, the average height of giraffes increased.
In 1850 CE, Charles Darwin discovered that living organisms did not come into being as they look today. He proposed that all creatures originated as small and simple ones; gradually, they developed into bigger and complex ones. He explained how and why small fishes evolved into larger ones, lizards into crocodiles, donkeys into horses, chimps into humans and so forth.
Scientists could not observe such evolutions among living animals, since each perceptible development took several millennia. In order to visualize the evolution of animals, they turned to palaeontology and studied prehistoric remains found all over the world. They invented several techniques, such as carbon dating, to detect the age of fossils. Using these techniques, scientists could determine the period when a fossil was alive on the earth. Apart from age, modern scientists could also precisely interpret the lifestyle, diseases and the cause of death of human remains.
Gradually, during the last century, the development of palaeontology established Darwin’s theory. Now, scientists have discarded all the religious theories; these merely have historical importance. Today, the biochemical origin of life known as the Oparin-Haldane theory is widely accepted, since scientists have enough evidence to prove it.