Succession of life(darwin and lamark theory)

  On the basis of succession of life on earth Darwin gave an extraordinary theories to explain why the life is succeeded on the earth yet? He pointed out some of the major factors which are responsible for this succession and he named it as law of variation. So the factors are –

1)variation under domestication
2)variation under nature
3)struggle for existence
4)natural selection (survival of the fittest)

On the basis of the factor he gave the explanation with example

1). variation under domestication

Darwin explains that there are the two factors which are responsible for the changes or variation

1)nature of organism
2)nature of the conditions

He said some of the species even eat the food at the same climatic condition but their offspring are observes as having deviation might be their in hair,skin etc so such deviation of morphological(outer part) and anatomical(inner part) might be due to those two conditions he gave an example of a domestic duck he said if we observe to the domestic duck that their wings bone seems to be very weak but their leg bones are strong but in the case of the wild duck their wings bone are stronger as compared to their legs this is because in the case of domestic duck they have to use their leg more as compared to their wings so their leg get evolve faster than wings but in the case of the wild duck they have to use their wings a lot to fly but they use their leg little bit so that’s why their wing bones seems to be stronger as compared to their leg. So this shows the domestic variation leads to the change in behaviour and way of living of organisms. The variation under domestication became a major factor for the succession of life towards the future.

2) variation under nature

The variation under nature means the variation of organism takes place due to change in the climatic condition ,geological condition. For example- human appendix we can see it in our lower abdomen. In the ancient period it plays a very very vital role in digestion process because in ancient period the human don’t know how to fry the meat what they have captured so human developed the appendix just to digest the meat. But now human are frying the meat before they eat so the appendix became disuse for human though it is thousand years phenomenon (I,e) we don’t notice it similarly many organism have evolve themselves to survive so those organism are able to evolve themselves means their anatomical(internal) and morphological(outer part) according to the change in environment they can only survive and other get extinct and even get disappear.

3)  struggle for existence

The factors that are affecting the existence of living organisms are
1)predator
2)sudden climatic change
3)heredity(phenotype and genotype) traits
As per of the illustration of Darwin the proof was got in 1946 when the population of peppered moth increases in uk . at that time there are two types of moths are their one is dark colour peppered moth and another is colourful peppered moth so in the 1946 due to the industrial revolution in uk in that particular area where the revolution was at it top the pollution increases suddenly so due to pollution the colour of leaf and trees that get blackened so now the predator can not see the blackish or dark moths as they are able hide themselves very easily. But the coloured moths was easily seen by predators so within 10 years the population of dark moths increases in uk but due to the clean air act on 1956 the dark moth became rare again because the black colour dirt that were produced by industry which help black or dark moth to hide themselves from the predator so now when the area was cleaned then the coloured moths are able mix with the natural beauty of nature then the dark peppered moth became rare again . this gives an example of struggle for existence. So as the sudden change in the condition of nature the colourful moth were not ready for it so they became extinct and the population of dark moth increases rapidly and when the environment get clean that produces an reverse effect to their population. So struggle for existence also plays a very vital role in the succession of life on earth.

4) natural selection (survival of the fittest)

As the word come natural selection means the nature has the ability to select the organism who are fittest to this changing environment. Darwin gave an example of natural selection he started observing a same kind of species in the finches island. After some time Darwin observe something strange about the finches peak. He observe that some finches has long peak and some finches have very short peak though they belong to the same species so how it can be possible? Then he observe the both type of finches for several month then he got the answer that the finches who have the small peak they are generally herbivore in nature means they are vegetarian in nature they eat food like leaf, flower etc that’s why they have very small peak even their offspring also have very small peak and the finches who have very long peak they must be non-vegetarian their long peak help them easily to carry fish from the water and even the earthworm that’s why their peak has evolved because it has so use.

Jean Baptist Lamark theory of use and disuse

Lamark further elaborated the Darwin's theory of evolution .lamark famously argued two theory one is use and disuse theory and as I have gave the example before about the human appendix if that particular organ is in use it further evolve if that particular organ is not in use then slowly it get disappear. His second point was he argued that the acquired traits were heritable .examples of what is traditionally called as Lamarckism would include the idea that when giraffes stretch their necks to reach leaves high in trees (especially acacias),they strengthen and gradually lengthen their necks
These giraffes have offspring with slightly longer necks(also known as the ‘soft inheritance’)similarly a blacksmith ,though his work ,strengthens the muscles in his arms, and thus his sons will have similar muscular development when they mature.
So Lamark stated the following laws on the basis of this-

1)first law-in every animal which has not passed the limit of its development , a more frequent and continuous use of any organ gradually strengthens, develops and enlarges that organ, and gives it a power proportional to the length of time it has been so used ; while the permanent disuse of organ imperceptibly weakens and deteriorates it, and progressively diminishes its functional capacity, until it finally disappears.

2)second law-all the acquisitions or the losses wrought by nature on individuals, through the influence of the environment in which their race has long been placed, and hence through the influence of the predominant use or permanent disuse of any organ ; all these are preserved by the reproduction to the new individuals which arises, provided that the acquired modifications are common to both sexes, or at least to the individuals which produces the young ones.
So, a change in the environment brings about change in ‘needs’ ,resulting in change in behaviour ,bringing change in organ usage and development ,bringing change in form over time ,and thus the gradual transmutation of the species takes place.
So this was all about how the life got the licence for the retention of the organism in earth.