Evolution

• Earth is 4500 million years old
• Life began 3500 million years ago
• Debate whether life developed due to the conditions on Earth or simple life forms arrived from another planet
• Fossils are found in rocks
• Can date when the different organisms existed

• Lemarck thought that acquired characteristics were passed on to the next generation
• Darwin's theory thought that small changes took place over time
• Natural selection meant that organisms vary and are more likely to survive
• Best adapted breed will pass on their characteristics

Natural Selection

• Survival of organisms with the best characteristics is known as the survival of the fittest
• The best adapted plants and animals survive due to natural selection
• Organisms of a species all vary from one another

Extinction

• means that a species that once existed has been completely wiped out
• always involved a change in circumstances
• a new disease may kill all members of the species
• climate change can make it too hot, too cold, too wet for a species and reduce food supply
• a new predator could kill and eat all the new species
• a new competitor may evolve and the original species will be left with nothing to eat
• the habitat that the species live in may be destroyed