How did life originate on Earth? Man has been interested in this problem from time immemorial. Today, taking part in this search are biologists, chemists, biochemists, biophysicists, geophysicists, geologists and even astronomers. Scientists have decided that life originated on Earth as part of general development of nature. Here is what Academician Alexander Oparin has to say on the subject. “It has been established that life has existed on Earth for a much longer time than it was at first assumed. Billions of years went by before the foundations for biological metabolism were formed and the cell – “brick” for everything living was born.”
To discover its beginning is to find out, first of all, whether carbonic compounds used to exist on the pre-biological Earth. At that very far-off time the Earth was enveloped in an atmosphere which lacked oxygen and was composed of gases-amonia, methane and hydrogen and water vapour. Carbon monoxide and other compounds were also present in the atmosphere of the Earth. The solar ionizing irradiation could activate the molecules of carbonic compounds, ionize them and make them capable of reaction. The reactions happened between the substances in the atmosphere and in the primeval ocean on the one hand and the compounds which were located on the surface of the Earth on the other. These reactions gave birth to the simplest compounds which later on became the components of the high-molecular compounds which are included in living organisms. Later on they started to precipitate from the solution in the special colloid form, the so-called coacervate droplets.
The coacervates competed with one another and a sort of struggle for life set in. The best organized coacervates with universal properties won. These high molecular systems and the compounds included in them later on had passed through the whole world of living beings. The same compounds are found in the cells of most varied living organisms.
But coacervate droplets lacked the ability to conduct metabolism, one of the many properties which a living being must possess, and they lacked such properties as changeability - the ability to take on different forms, the simplest form of heredity, and lastly interaction with the environment from which it has to absorb the necessary materials.
How did nature cross this barrier? Science as yet cannot provide a simple answer to this question. Apparently it was some sort of intermediate formation - we call it the probiont.One thing is evident, that nature has pierced this barrier once, so man will be able to reproduce that act in an experiment.
When man learns the biological phenomena of life he will learn also to control them. Putting nature under control people will provide an abundance of food for themselves and will decorate the globe with useful plants. Diseases will become a thing of the past. When they study the past, the scientists think of the future.
(Adapted from the Internet sites)
6.4 Read the text to know more about the famous Russian physiologist I.M. Sechenov.
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