Charles Darwin
The Father of Naturalism
Charles Darwin revolutionized the way we viewed the natural world, and in tandem with a few other scientists, solved some of the greatest questions in biology.
2nd Voyage of The Beagle
The 5 year journey Charles Darwin embarked on was crucial to his later theories. Originally Darwin joined to provide his services in geology, since he was interested in new fossils and wished to see the distant places of the world. And while it was a sea voyage, he spent 39 months on land and 18 months at sea. While on the trip he formed new theories about the movement of land, the distribution of organisms, both which culminated in undermining his belief in the stability of fixed species. This was heavily supported by his time in the Galapagos.
Forming the Theory
There were two major things which helped Darwin develop his Theory of Evolution Through Natural Selection; the fossil record he found in South America and the existing variation in similar species in the Galapagos.
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While on the voyage Darwin would frequently conduct land excursions in search of fossils, due to the lack of knowledge in the area at the time. He would often find large bones of extinct megafauna, stimulating the question of why they no longer lived. He then discovered fossilized coastal trees 2 km above sea level, which was quickly provided an answer to, when after an earthquake in Chile, Darwin noticed the previously submerged mussel beds where now above the high tide mark, causing him to start thinking in tens of millions of years, the time needed for evolution to take place.
Study on the Islands
The Beagle arrived in the Galapagos on September 16th 1835, visiting the island San Cristobal. They spent 8 days travelling the island, and he was particularly interested in the vibrancy of such a isolated island. He also collected what would become one of his pieces of evidence for evolution, a San Cristobal Mockingbird.
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He spent 3 days on the next island, Floreana, and found a second species of mockingbird to collect. While here he met an English Official who taught him how to recognised tortoises by island by looking at the shells.
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Isla Isabela was the third stop on September 19th, where Darwin took detailed note on how barren it seemed and the volcanic activity. He then studied the iguanas, both marine and terrestrial variations, and began thinking about the difference between them.
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The final stop was Isla Santiago, where he spent two weeks trekking around the island, studying the differences between these tortoises and the ones he had seen previously. This culminated to him starting to collect different finches after realizing the similarities between species. The Beagle left the Galapagos on October 20th, after spending 5 weeks in the archipelago.
On the Origin of Species
Contrary to popular belief, Darwin didn't understand the full importance of what he saw in the Galapagos. It was only years later he realized in hindsight the differences between animals could be caused by differences in islands, and used comparative analysis of his specimens to fill in the gaps. It then took him many more years to create a comprehensive study on it which attempted to include all life on Earth. It was only in 1859 he released it to the public, 25 years after arriving back in England after the trip.