for the first time in Ecuador when he was 26 years old. He got
astonished by the great quantity of turtles and iguanas that live
in this area, to which he referred as "the paradise for the
reptiles." In the scientific expedition on board the Beagle,
Darwin traveled in five weeks most of the main islands of Galapagos
(San Cristóbal, Floreana, Isabel and Santiago).
In the archipelago
he found plants and animals of the same type. Even fossils of
extinct animals similar to the modern ones. This way, the naturalist
supposed that the marine iguanas came from the terrestrial species
of reptiles that extinguished hundred of millions of years ago.
13 species of chaffinches (terrestrial birds) known as they were
studied by Darwin. The naturalist sustained that these birds evolved
starting from a unique group, for what concluded that the changes
were gradual and that millions of years passed, before they adapt
to the environment and before they transmit the new characteristics
to the following generations.
that the mechanism of the evolution was a process called natural
selection and that most of species come from one unique branch.
As a result of his investigations, he published the book "The
Origin of the Species", in 1859.