Evolution

Selection and change.

All living organisms show adaptation. They have characteristics that make them well suited to a special way of life in the unique habitat in which they are found. But how does this adaptation take place?

We first start with a chemical change in one or more of the genes of an individual during cell replication. Such chemical changes of a gene lead to new characteristics and are known as mutations. Mutations that occur in sperm or egg cells can be passed on to the next generation. Mutations are the building blocks of evolution and give rise to variation within a population.

The variable characteristics resulting from mutation will only increase in frequency, within a population, if the characteristic assists individuals to survive and reproduce. The variations that place the individual at a disadvantage will become less frequent and disappear from the population.

 
Individuals with characteristics that give them an advantage in finding food, surviving the climate or escaping predators are likely to live longer and to reproduce, thus passing on their characteristics to the next generation. Individuals with characteristics that place them at a disadvantage in the hunt for food or avoiding predators are likely to die before they can reproduce. This process by which characteristics are chosen to succeed or fail is known as natural selection. One of the consequences of natural selection is adaptation.

 

Before we continue let's clarify one issue that keeps appearing when discussing evolution. The creationists have countered evolution with questions such as "If we evolved from monkeys why are there still monkeys about and not died off?".

View the video on the right. It shows a reality show contestant, born again christian, asking the question above in defence of creationism.

How are Chimpanzees and Humans related?

Which one of the following are Humans more closely related to?
- gorillas

- Bonobos

What group of apes are Humans a part of?

Which two apes out of, Bonobos, Humans and Chimpanzees are the most closely related?

 

 
 
Support for evolution
Continue Lets look at the stick insect population to clarify the concepts we have just discussed.
Evolution and endosymbiosis
Evolution of the eye
Molecular evolution and the early Earth.
Parasitic fungi and mind changing behaviour.
Evolution of skin colour
Kangaroo
Evolution of superbugs-the new challenge for antibiotics against the new generation antibiotic resistant bacteria