Origin of life on earth

 History of origination👸

What is Evolution?

Any process of formation or growth; development:
In other words, Evolution is a process of gradual, peaceful, progressive change or development, as in social or economic structure or institutions.

In biology,Evolution refers to a gradual change in the characteristics of a population of animals or plants over successive generations: accounts for the origin of existing species from ancestors unlike them

Evolution on earth

HISTORICAL USAGE OF EVOLUTION

Evolution comes from Latin ēvolūtiō (stem ēvolūtiōn- ) “unrolling a papyrus scroll, reading through (an author's words or a book),” a derivative of the verb ēvolvere “to roll out or away, unroll (a papyrus scroll), uncover, unwrap, unfold by using the intellect.”
The earliest English meaning of evolution, “a movement or series of movements of troops or ships into battle formation,” dates from the early 17th century. The modern, biological sense “change in the gene pool of a population from generation to generation by mutation, natural selection, and genetic drift,” first appears in 1832 in the works of British geologist Charles Lyell in a discussion of some invertebrate sea creatures.
Charles Darwin did not use the word evolution at all in his first edition of On the Origin of Species (1859), although he did use the verb evolved at the very end of the book. Darwin preferred descent with modification, because the idea of progress had no place in his theory or work. It was his contemporary Herbert Spencer who, embracing Darwin's work, popularized evolution in its biological sense and also extended the word into ethics, philosophy, and sociology.

John Burdon Sanderson
Haldane FRS,
nicknamed "Jack"

J.B.S Haldane

(He gives the theory of history of life)

Haldane was born in Oxford to John Scott Haldane, a physiologist, scientist, a philosopher and a Liberal, and Louisa Kathleen Trotter, a Conservative. His younger sister, Naomi Mitchison, became a writer, and his uncle was Viscount Haldane and his aunt the author Elizabeth Haldane.

Suggestion on origin of life:

A British scientist J.B.S Haldane suggested in 1929that life must have developed from the simple inorganic molecules(such as methane ,ammonia, hydrogen sulphide, etc.)which was present soon after the earth it was formed. He said that the conditions on earth at that time including frequent lightning could have converted simple inorganic molecules into complex organic molecules which were necessary for life.

These complex organic molecules must have joined together to form first primitive living organisms. Haldane also suggested from theoretical considerations that life or living organisms originated in the water.

The theory of origin of life on earth proposed by Haldane was confirmed by experiments conducted by Stanley L. Miller and Harold C. Urey in 1953.They assembled an  apparatus to create an early atmosphere which was proposed to consist of gases like methane,ammonia, hydrogen sulphide, etc,(but no oxygen),over water. This was maintained at a temperature at below 100 degree Celcius and electric sparks then passed through mixture of gases(to stimulate the lightning) for about one week.

At the end of one week,it was  found that about 15 percent of crbon has been converted into simple compounds ofcarbon including 'amino acid'which make up protien molecules found in living oganisms.

 This experiment provides the evidence that the life originated from the inanimate matter(or lifeless matter) like  inorganic molecules. 

Theories on the origin of life:

The origin and evolution of the earth

Early Theories

Nebular Hypothesis

• Immanuel Kant, a German philosopher, gave this theory.
• In 1796, a mathematician Pierre-Simon Laplace reexamined it.
• According to this hypothesis, the planets were moulded out of a cloud of material associated with a young Sun, which was rotating slowly.

Binary theories

• As per these theories, the sun had a companion.

Revised Nebular Hypothesis

• Revised Nebular Hypothesis was propounded by Carl Weizascar in Germany and Otto Schmidt in Russia.
• They regarded that a solar nebula surrounded the sun and that the nebula comprised of chiefly hydrogen, helium and something called dust.
• The collision of particles and the friction caused a disk-shaped cloud to be formed and then the planets were created via the accretion process.

Modern theories

Big Bang Theory

• Alternatively called the expanding universe hypothesis.
• As per this theory, in the beginning, all matter or substance forming this universe existed at one place as a tiny ball. This tiny ball had an extremely small volume, infinite density and temperature.
• At the Big Bang, this ball blasted fiercely and forcefully and started a substantial process of expansion which continues to this day.
• Now it is accepted that this event took place 13.7 billion years ago.

Origin of Earth

Formation of Planets

The following are regarded as the stages in the planets’ development:

• The stars are localised gas lumps inside a nebula.
• A core to the gas cloud as well as a spinning disc of dust and gas are created because of the gravitational force within the lumps.
• After this, the cloud of the gas condenses and the matter over the core is changed into tiny rounded objects.
• These small round objects develop into what are called planetesimals by a cohesion process.
• The smaller objects start forming larger bodies by colliding with one another and they stick together because of gravitational force.
• In the last stage, these large number of small planetesimals aggregate to develop into a smaller number of large bodies called planets.