Darwin and natural selection, Science

Darwin and Natural Selection:

The English naturalist Charles Darwin (1809-1882) explained how biological evolution took place,  in his remarkable "The Origin of  Species" in 1859. Darwin began his observations at the age of  22, as a naturalist on H.M.S. Beagle, which was a sail ship going round the world. He spent five advent~irous  years on the voyagc. During this period, he visited may islands of  the Atlantic Ocean, some parts of the coasts of  South America, and some islands of  the South Pacific, of which  the Galapagos is the most important. This  journey gave Darwin a prolonged exposure to an area of  the world, radically different in  its plant and animal life from his native place. He collected and preserved a lot of material and took extensive notes throughout the voyage. 

 

184_Darwin and Natural Selection.png

Once back  in England, he spent nearly 22 years examining his collection and pondering over the question of  how evolution of species could have taken  place. He drew the evidence from three important areas:  the record of  the rocks,  in which he discovered  fossils and imprints of creatures of  the past ages; the distribution of  animals and plants in the world; and finally from the study of  the breeding experiments that were going on in the nineteenth century to improve life stock or to breed dogs and pigeons. Darwin's great innovative step was to introduce the theory of  'natural  selection'  as the mechanism  for evolution.

Though the credit for giving this theory*  is generally given to Darwin, another English naturalist-Alfred Russel Wallace had conceived the theory of evolution  independently at'the same time. The work of  the two scientists was presented 'jointly at the meeting of  the Linnean Society in London in 1858. The theory began with two observations. First. more organisms are born  than can survive to reproduce: themselves, because the environment has limited means of  subsistence. This overproduction  results in a struggle for existence and ultimate survival of the fittest. Plant and animal species compete within and among themselves for food, water, air, light-everything that enables organisms to survive and reproduce.

The  second observation is that offsprings, i.e, children differ slightly from their parents and from each other in characteristics which they inherit. This we now call genetic variation. Darwin held  the view that these variations are a source of  evolutionary change. According to him in any group, individuals with characteristics which enable them to adapt best to their environment survive and reproduce, while those who lack these characteristics have a poor chance of  survival. Thus, Nature selects and preserves the useful variations in a changing environment, Darwin called this natural  selection. 

Posted Date: 9/28/2012 3:32:36 AM | Location : United States







Related Discussions:- Darwin and natural selection, Assignment Help, Ask Question on Darwin and natural selection, Get Answer, Expert's Help, Darwin and natural selection Discussions

Write discussion on Darwin and natural selection
Your posts are moderated
Related Questions
Explain the Maintenance of Electrolyte Balance In the process of formation of urine, the kidneys also maintain electrolyte balance. Sodium is the most important cation that exi

Explain the Thyroid Stimulating Hormone (TSH): TSH, also known as thyrotropin is a glycoprotein and synthesized by thyrotroph cells of the anterior pituitary gland. Its functio

State about the Peaty soils Peaty soils occur in humid regions and have an accumulation of high organic matter. Such peaty soils containing considerable amount of soluble salt

What is Classic Technique of Recipient Operation ? In this method, portions of left and light atria of both recipient and donor are retained. There is more atrial tissue of rec

To feel the 'spring' of air Secure a bicycle pump and place your thumb over the finish of the outlet tube. Next push the piston in forcibly and rapidly let go of it. What happe

Explain the Serum Creatinine Test Creatinine is a breakdown product of creatine, an important component of muscle. A serum creatinine test measures the amount of creatinine in

Which describes granite and basalt?

Are these people a worker in a farm? Which is the Independent and Dependent variable and Control group.

To study a hailstone When it hails, collect some of the hailstones. Cut them in half and view how the ice of the hailstone has been built up in layers. If you live in a region

The diagram below shows a baffled tank with a six blade turbine agitator: FIGURE 1 (a)    Is a side view (b)   Is a bottom view (c)    Gives dimensions of the tu