Biologist, naturalist, geologist. Charles Darwin made his mark on science in several ways. However, it was his revolutionary theory of evolution that catapulted him into the history books.
Born in 1809 to a doctor and an heiress to the Wedgwood pottery company, Darwin was expected to follow in his father’s footsteps. While studying medicine at Edinburgh University, Darwin showed little interest in his proposed profession, but the people and ideas he was introduced to would have a formative effect on the scientist’s young mind.
Darwin was much more interested in the natural world and he learned valuable lessons in biology, such as how to classify plants and how to stuff birds. He was exposed to radicals and freethinkers; surrounded by students discussing divine design and arguing against this hitherto-accepted explanation of the world. He also met evolutionist Robert Edmond Grant who taught Darwin about the growth of primitive marine life, which Grant believed was key to understanding the origin of more complex lifeforms.
Realising that his son was not on course to complete his medical education, Darwin’s father moved him to Cambridge University to pursue a career in the church instead. But before he took up a position as a clergyman, Darwin was recommended to join a voyage to Tierra del Fuego in South America – a journey that was to change Darwin’s life and lead to one of the greatest scientific breakthroughs in history.
HMS Beagle left England in December 1831. The ship’s circumnavigation of the globe would take five years. Throughout the voyage, Darwin collected samples, made sketches and kept diaries all of which helped to formulate his bold new theory.

For half a decade, Darwin endured physical and mental hardships alongside thrilling adventures. He trekked through dense rainforest, hiked Andean mountains and even became entangled in a rebellion in Uruguay. In Argentina, Darwin collected fossils of extinct creatures leading him to consider the prehistoric world and what had caused the extermination of these animals.
Inspired by Charles Lyell’s Principles of Geology, Darwin made many observations about the land around him. In Chile, he climbed 1200 metres into the Andes and was awed by the forces that could create such mountains. He also witnessed a volcanic eruption at Mount Osorno and experienced an earthquake that flattened the city of Concepcion. While walking through the rubble, Darwin noticed the mussel beds lying above the shoreline. He had also seen trees fossilized in sandstone at more than 2000 meters above sea level. This evidence supported Lyell’s theory that the earth was gradually being forced upwards. Darwin started to ponder on how long this process must take and began thinking in terms of deep time.
Darwin’s most famous expedition on the voyage was the time he spent exploring the Galapagos Islands, Ecuador. HMS Beagle was homeward bound when it left Peru in September 1835 and landed in the Galapagos. Darwin encountered creatures unknown anywhere else on the planet, including marine iguanas, giant tortoises and Galapagos penguins. He noticed that finches on each of the islands had distinct shaped beaks, an observation that was to prove crucial to his theory of evolution.

On his return in 1836, Darwin settled into life as a geologist and published his diaries from his journey as well as a book about the biological specimens he had collected. Darwin was making a name for himself in scientific circles and all the while, in private, he was devising his theory of evolution.
It wasn’t until 1859 that Darwin eventually published his seminal work, On the Origin of Species by Means of Natural Selection. He had delayed presenting his theory for many years, concerned about the reception it would have in Victorian England. His theory flew in the face of strongly held religious beliefs of the 19th century and, as predicted, it sent shockwaves through English society.
Despite this, his book was received in the scientific community with interest and became a bestseller. Darwin’s theory was doggedly defended by his peers, most notably young biologist Thomas Huxley, while Darwin retreated from public life due to illness and personal tragedy.
In scientific circles, the book continued to gain popularity and On the Origin of Species became so influential it was translated into a dozen languages in Darwin’s lifetime. Darwin also released several editions, each responding to critics and further strengthening his arguments. In the fifth edition, he used a phrase that has become shorthand for his theory: survival of the fittest.
When Darwin published The Descent of Man in 1871, his theory had gained significant acceptance. Although society was still divided about the idea that humans are descended from apes, by the time of his death in 1882 many respectable thinkers were ‘Darwinists’.
Accepted today as unarguable science, Darwin’s revolutionary idea challenged beliefs, questioned the way we think about the world, and crucially, changed how we see ourselves as a species. Few other scientists have left such an indelible mark on history.