Darwin embarked the HMS beagle with captain Fitzroy, a journey that lasted about five years going around the world and studying species from different islands. Form these species his theory of Evolution was born. He came up with the idea because the animals he was studying were alike but had different characteristics. He then came up with the theory of natural selection, this referred to that animals had to reproduce to produce and keep their genes.
Charles Darwin had a hard time deciding whether or not to publish his book on his theory because everyone believed in the creation of God. Therefore anyone who spoke differently was accused of heresy and had consequences.
Source: http://www.age-of-the-sage.org/philosophy/charles_darwin.html
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