Evolution



Everyone has heard of it, but what do you need to know about it? Firstly, there are two main characters in the arena and they had different ideas.

1) Jean-Baptiste Lamark believed that characteristics that you build up in your life-time would be passed on to your children. Basically, if you and your partner weight lifted every day and became very muscular, your children would be born muscular also. We know this to be impossible now as no matter what you do in your lifetime, it will not alter your chromosomes and these are what are passed onto your children.

2) Charles Darwin went to the Galapagos Islands and suggested that through "natural selection" animals that have special characteristics that help them to hunt, eat or survive are more likely to be passed onto offspring as the parents will survive longer and have more babies. These individual episodes of natural selection add up together over a very long period of time to become Evolution.

Darwin's finches evolutionDarwin's evolutionary tree finchesBasically, an animal is born with a natural variation that allows it to avoid being eaten will live longer and have more babies so passing on this characteristic to more of the next generation.

Darwin's theory was only accepted gradually over a long period of time. The main opposition was due to lack of firm evidence and the strongly held belief that God had made everything. Because Darwin did not know about genes, he could not explain about variation which we covered in the last topic. A variation is a mutation of a gene where a characteristic never before seen in that species' history.

The finches that Darwin saw all had common ancestors, however, they were all different. They had evolved through natural selection. Each finch had a beak best suited to the food it ate as seen in the picture on the left.

One day, a bird was born with a beak that made it easier to eat seeds. This variation made it easier for that bird to get enough food so it became very successful. It mated every year and its children also had this beak. Because it was so successful, it lived a long time and had more children than the other finches because when they were dead, it was still producing offspring. Also, other finches would have wanted to mate with this one because of its success. After many years and many generations, all of the finches in that area have that beak and are successful seed eaters, that is evolution through natural selection.

Other examples include camouflage, speed and strength and there are many more. This is also known as "survival of the fittest".

By putting organisms into groups together with similarities, we can see how they are related. These are called classifications. The Natural Classification System is used to study the evolution of organisms. This simplest are "The Kingdoms" comprised of Plant Kingdom, Animal Kingdom and Kingdoms of microorganisms. At the other end of the spectrum, the smallest group in a classification are the "species". Only members of the same species are closely enough related to produce offspring.

 This leads us to this diagram on the right. It is an Evolutionary Tree showing us that the closest relative to the Ground Finches is the Cactus Finch and the Warber Finch has evolved least and that they all had one common ancestor from which they all evolved. As they all lead to present day, none of the lines stop before getting to the right, none of the species have gone extinct.



Key words and terms for this topic: evolution, Jean-Baptiste Lamark, inheritance of acquired characteristics, Charles Darwin, mutation, survival of the fittest, classification, kingdom, species, evolution, evolutionary tree.

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