Charles Darwin Theory of Evolution
In 1859 darwin published his book the origin of species:
Darwinism can be described as follows :
Over production of offspring:
According to Darwinism population
tend to multiply geometrically and living organisms have more reproductive
power than required to maintain their number.
Struggle for existence :
The organisms reproduced at very
rapid rate but the foodna dspace on the earth is limited. As a result , start
competition between the organisms havin similar requirements .This competion
between the organisms for basic needs of life like food, space, etc. is known
as struggle for existence, It may be:
Intraspecific(between the members
of same species)
Interspecific(Between the members
of different species)
Environmental(The struggle against unfavourable
environmental condition like earthquake, valocano , flood)
In
this struggle many individuals died before reaching the sexual maturity and
only few individuals survive. So, struggle for existence maintains the number
of organisms remains constant.
Variation:
It is the difference between the
individuals . It is common in nature, Variation may be continuous or
discontinuous continuous variation means small indistinct changes while
discontinuous variations are large scale changes,the variations may be useful,
harmful or neutral. Darwin
protposed that living organisms adopt to the changing environment due to useful
continuous variations.
Nautral selection or survival of the fittest:
Nature select only those oranisms
which are with useful continuous variations and best adopted to the
environment, while others are eliminated . In other words, we can say that
nature select those individuals which are fit to survive.
Origin of Species :
According to Darwinism , variation
appear in every generation and are inherited from one generation to another. So
, these variation are go on accumulating and after a number of generations
variation become so prominent that the individual turns into a new species.
Demerits of Darwinism:
1.He didn’t explained the causes
of variation He said that continuous variation are mainly responsible for the
evolution which is not true .
2. Darwinism explains that useless or harmful characters are not selected by the nature while many vestigial organs are found in different organisms.
3. Darwinism is not able to
explain the inheritance of over specialized organs like tusk of elephant, etc.
4. Natural selection doesn’t
explain the development of new characters while only the modification in the
pre – existing ones.
Some quotations by Charles Darwin:
It is not the strongest of the species that survive, nor the most intelligent, but the one most responsive to change.
A man who dares to waste one hour of time has not discovered the value of life.
The mystery of the beginning of all things is insoluble by us; and I for one must be content to remain an agnostic.
The highest possible stage in moral culture is when we recognize that we ought to control our thoughts.
A scientific man ought to have no wishes, no affections, - a mere heart of stone.
If the misery of the poor be caused not by the laws of nature, but by our institutions, great is our sin.
I love fools' experiments. I am always making them.
An American monkey, after getting drunk on brandy, would never touch it again, and thus is much wiser than most men.
We
must, however, acknowledge, as it seems to me, that man with all his
noble qualities... still bears in his bodily frame the indelible stamp
of his lowly origin.
A man's friendships are one of the best measures of his worth.
(Quotation source : en.wikipedia.org)
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