Darwin states his Conclusion
Theory of Evolution:
"Origin of Species"
Darwin's theory explains why humans and other animals look the way we do! Forexample, the reason why Giraffes have long necks is explained as follows:
The Theory of Evolution
The Theory of Evolution could easily have been called the Theory of Mutations.
A mutant, or a creature with a mutation, is an offspring who differs slightly from its parents. For example if the parents of a child are 5' 5" tall and 6' tall but the child is 6'3" tall, then the child is a mutation of the parents. If the parents have dark brown eyes and the child has light brown eyes, then the child is a mutation of its parents. We are all mutations in one aspect or another. It is a fact of life that offspring will have many characteristics that differ from their parents.
Now, lets consider the life of a giraffe.
How did giraffes get such long necks? The answer is manifest in the Theory of Evolution.
Much of the day of a giraffe is spent eating leaves off of trees. They dont have much competition, except for other giraffes. Once in a while a SHORT giraffe will be under-nourished as the TALL giraffes can always eat the higher leaves when the lower ones are all eaten.
This poor SHORT giraffe will be weak and easy prey for predators and disease. He may die before he even had a chance to find a mate. Most of the TALL giraffes will have no problem and will even have offspring - baby TALL giraffes.
Of course, most of the SHORT giraffes make do and also survive. But after thousands of years, the number of SHORT giraffe fatalities is sufficiently greater than the TALL giraffe fatalities that the TALL giraffes start to outnumber the SHORT giraffes by quite a margin. However, after thousands of more years, the TALL giraffes are also having a few problems.
There are now a few offspring that are mutations of the TALL giraffes they are - the "TALLER" giraffes!
Many thousands of years pass and the competition of the TALL giraffes AND the TALLER giraffes has been too much for the poor SHORT giraffe family and they are now extinct. The SHORT giraffes have been a victim of the " survival of the fittest " !! [Also called The Theory of Natural Selection]
Now the TALL giraffes are becoming under-nourished and weak and easy prey for predators and disease. The TALLER giraffes soon start to outnumber the TALL giraffes.
After thousands of years more, the TALLER giraffes are having their turn at a few problems. There are now a few offspring that are mutations of the TALLER giraffes - they are - the "TALLER-YET" giraffes! Soon the TALL giraffes will be extinct and only the TALLER and the TALLER-YET giraffes will survive.
Of course, such a process will stop when all giraffes are tall enough to reach any leaves.
This is Darwins theory. Indeed giraffes dont stretch their necks and pass along stretched necks to their offspring. Instead, slight variations called mutations and survival of the fittest and thousands, if not millions of years determine the future of a species.