Was Darwin Wrong?

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Table of Contents
Who was Charles Darwin?
Charles Darwin was born in 1809 in Shrewsbury, England. Originally, Darwin did not believe in the idea of evolution and trained to be a priest before studying geology and biology. In 1831, when Darwin was 22, he set sail around the world on HMS Beagle, a naval survey ship. The trip lasted for 5 years during which time the ship stopped at many places including the Galápagos Islands, just off the west coast of South America. Darwin examined animals and plants from everywhere he visited, taking specimens back to England and recording his observations in a diary. However he was most intrigued by the finches on the Galápagos Islands... What was Darwin’s Theory of Natural Selection?

Darwin noticed that there were wide variations in the finches’ size, beaks and claws. He decided the beaks were designed for eating different things and concluded that the finches must have evolved from just one species which had changed over time. They had adapted to their surroundings. In order to begin to understand natural selection, it is important recognise how the many hundreds of thousands of living organisms are classified. The diagram on the next page shows an example of how we determine a species. {draw:frame}

A species can be defined as a group of organisms so similar they can breed together to form fertile offspring. For example, a horse and a donkey can breed to produce a mule but the mule, is infertile therefore showing a horse and a donkey are of different species. Within a species there are still differences and this variation is very important in evolution because without them, natural selection could not occur. Variation can be either genetic, environmental or a combination of both. For example: Variation caused by genes includes eye colour , gender

Variation caused by the environment includes accent
Variation caused by a combination of both includes high blood pressure, weight Nearly all variation is caused by a combination of these factors. Many people before Darwin thought about evolution and most scientists agreed that life on earth started from a few, simple living things. Alfred Russel Wallace and Jean Baptiste de Lamarck both had ideas about evolution, but Darwin was the first to come up with a plausible idea of how evolution happened. This is what he called Natural Selection and when he returned from his round the world trip, Darwin spent over twenty years working to prove his theory. Wallace wrote to him asking him for advice and together they wrote a paper about evolution. To summarize, Darwin’s theory is basically:

Species change over time. This is supported by the fossil record. All organisms share a common ancestor which explains the similarities between organisms that are classified together. This is supported by evidence of vestigial organs and homologous structures (see page 6). Evolutionary change is gradual and slow. This is also supported by the fossil record. Another crucial conclusion Darwin made, was that there are always going to be too many of one species for each of them to survive. This is because they will always be in competition for food and space. He established that those best suited to survive pass their genes onto their offspring, which causes their species to change over time and could lead to their extinction. {draw:frame} {draw:frame} {draw:rect} {draw:frame} {draw:rect} {draw:rect} {draw:frame}

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Diagram to show the steps in natural selection
Why the population of a species changes over time
In the above graph, the Canadian lynx eats the Snowshoe hare. No other cat is so dependent on a single prey species. Two years after a rise in the snowshoe hare population, there is a rise in the lynx population. Then, the Snowshoe hare population falls. When...
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