Charles Darwin: the Theory of Evolution
Charles Darwin's most famous idea was the Theory of Evolution by Natural Selection.
In the mid 19th century Christianity, for the vast majority of people and their leaders, was considered a source of absolute certainty. There are still millions of Christians who believe in the Old Testament account of Creation. The greatest challenge to this account was Charles Darwin's On the Origin of Species by Means of Natural Selection, published in 1859. This gained its author the title 'most dangerous man in Britain'.
The Origin of Species gave detailed evidence for evolution, with natural selection as its driving force. Natural selection itself is driven by two things:
- More organisms are generated by sexual reproduction than can possibly survive.
- All organisms of the same species are different, for instance, no human has the same fingerprint.
There is competition between offspring, and only those whose differences make them more able to survive are likely to reproduce. This is called survival of the fittest.
These ideas seem obvious to modern readers, but produced a conceptual earthquake when they first appeared. They removed all concepts of human beings as being special, superior, and apart from the animal kingdom. In fact, they placed human beings in a direct line of inheritance going back through animals to single-celled life forms and, eventually, back to nonliving matter.
Before Darwin, Lamarck introduced the idea that characteristics acquired in a lifetime could be inherited. For instance, he thought that a Giraffe could acquire a longer neck by having to stretch for leaves on higher branches. This longer neck would then be passed on to its descendents. Darwin showed that this view was fallacious. Variation is purely inherited, there is no inheritance of acquired characteristics.
