12 April 2009

Evolution 101, part I

It has come to my attention that there is a need for an online resource which explains evolution and natural selection in plain and accessible language. So I have decided to try my hand at compiling such a resource. Lets start from the beginning, shall we?

1. 'Life' from 'non-life'
This is one of the most misunderstood concepts in evolution. In 1953, Dr.s Urey & Miller showed how amino acids could have been formed on this planet by natural forces about 3.8 billion years ago. These Amino acids would have been the first organic compounds. Amino acids are what DNA is made of, and are essential to life. It has been shown that they have been produced by the naturally occurring conditions of planet formation, and there is some evidence to suggest that this one type of process has occurred on countless other worlds as well.

2. Evolution is not random.
Mutation is random. Mutation is simply tiny random changes that happen to DNA due to time, solar radiation, or chemical interaction. If these changes are passed on to a new generation, they may cause something that provides an advantage, in which case they are likely to get passed on again and become more common over time. If they cause a disadvantage, they are less likely to get passed on. That is what natural selection is. It is not random because mutations which give an advantage are more likely to help a person breed and raise healthy offspring, and mutations which are harmful are less likely to be continued because a person who has one is less likely to survive long enough to pass on their genes.

The definition of a beneficial mutation may change with environment. For example: A random mutation which causes a person to be taller and thinner than the average. In a hot climate, this would be an advantage because it would help them shed heat more effectively. It would likely get passed on. In a cold climate it would be a disadvantage for the very same reason. Therefore it would be less likely to be passed on there.

More to follow, hopefully with diagrams...

No comments:

Post a Comment

Have something to say about this? Say it!