Charles Darwin: history's most famous biologist
Charles Robert Darwin (1809-1882) transformed the way we understand the natural world with ideas that, in his day, were nothing short of revolutionary.
He and his fellow pioneers in the field of biology gave us insight into the fantastic diversity of life on Earth and its origins, including our own as a species.
He is celebrated as one the greatest British scientists who ever lived, but in his time his radical theories brought him into conflict with members of the Church of England.
Young Charles Darwin
Born in 1809 in Shrewsbury, Shropshire, Darwin was fascinated by the natural world from a young age. Growing up he was an avid reader of nature books and devoted his spare time to exploring the fields and woodlands around his home, collecting plants and insects.
In 1825 Darwin enrolled in medical school at the University of Edinburgh, where he witnessed surgery on a child. Surgeries at the time would have been carried out without the use of anaesthetic or antiseptics, and fatalities were common.
Watching this procedure left Darwin so traumatised that he gave up his studies without completing the course. He then went to Cambridge University to study theology.
The voyage of HMS Beagle
In no rush to take holy orders, in 1831 Darwin accepted an offer to embark on a five-year voyage aboard HMS Beagle.
He was recommended by one of his Cambridge professors for the role as naturalist and companion to the ship's captain, Robert FitzRoy.
The journey would change both his life and the trajectory of Western scientific thinking.
Darwin explored remote regions and marveled at a world so different from the one he knew. He encountered birds with bright blue feet, sharks with T-shaped heads and giant tortoises.
On his travels Darwin collected plants, animals and fossils, and took copious field notes. These collections and records provided the evidence he needed to develop his remarkable theory.
Darwin returned to England in 1836. A highly methodical scholar, constantly collecting and observing, he spent many years comparing and analysing specimens before finally declaring that evolution occurs by a process of natural selection.
What is the theory of natural selection?
To this day the theory of evolution by natural selection is accepted by the scientific community as the best evidence-based explanation for the diversity and complexity of life on Earth.
The theory proposes that the 'fittest' individual organisms - those with the characteristics best suited to their environment - are more likely to survive and reproduce. They pass on these desirable characteristics to their offspring.
Gradually these features may become more common in a population, so species change over time. If the changes are great enough they could produce a new species altogether.
On his travels Darwin had collected finches from many of the Galápagos Islands (off the coast of Ecuador), which helped him to formulate his idea.
Some of these finches had stout beaks for eating seeds, others were insect specialists. But Darwin realised that they were all descendants of a single ancestor. As they dispersed to different islands, the birds had adapted to eat the various foods available. Natural selection had produced 13 different species of finch.
From his travels on HMS Beagle, Darwin suspected that the environment might naturally manipulate species, causing them to change over time - but he couldn't find a means to explore this effectively in the wild.
Experimenting with artificial selection in pigeons gave him a way to study how far a species could change.
By artificially selecting features - crossing birds with particular characteristics to generate different offspring - he gathered valuable evidence for evolution by natural selection.
To illustrate his theory, Darwin bred the birds to have exaggerated features.
The similarity between artificial selection and natural selection is at the heart of his explanation of evolution in his revolutionary book On the Origin of Species.
After completing his experiments, he gave all 120 of his pigeon specimens to the Museum. They are currently part of the ornithology (bird) collections kept at Tring, Hertfordshire.
A shared discovery
Darwin knew his radical ideas would be met with stiff opposition. Even after 20 years of research, he worried about how his theory of evolution would be received as it challenged widely held religious beliefs of the time.
He delayed publishing on the topic for a great number of years while he assembled a mountain of evidence. When he learned that the young naturalist Alfred Russel Wallace had developed similar ideas, Darwin volunteered to send Wallace's ideas to a journal for immediate publication.
On advice from friends, the two scientists organised a joint announcement. Their theory of evolution by natural selection was presented at the Linnean Society in London.
Both had studied the natural world extensively and made a number of observations that were critical to the development of the theory.
The following year, Darwin published the contentious but now-celebrated book, ‘On the Origin of Species’.
On the Origin of Species
Published in 1859, On the Origin of Species provoked outrage from some members of the Church of England as it implicitly contradicted the belief in divine creation.
Despite accusations of blasphemy, the book quickly became a bestseller.
The Descent of Man, and Selection in Relation to Sex - which Darwin published in 1871 - fuelled even greater debate as it suggested that humans descended from apes.
The Bishop of Oxford famously asked Thomas Huxley, one of Darwin's most enthusiastic supporters, whether it was through his grandfather or grandmother that he claimed descent from a monkey.
Despite the attacks, Darwin's conviction in the scientific explanation that best fit the available evidence remained unshaken.
He was keen for his ideas to reach as many people as possible and for his books to be read in many different languages. Part of his success has been attributed to his conversational and approachable writing style.
On the Origin of Species was so influential that within a year it had been published in German. In Darwin's lifetime, this book was translated into German, Danish, Dutch, French, Hungarian, Italian, Polish, Russian, Serbian, Spanish and Swedish.
The Museum's Library has 478 editions of On the Origin of Species in 38 languages and in Braille.
Darwin and the tree of life
Charles Darwin used the concept of a tree of life in the context of the theory of evolution to illustrate that all species on Earth are related and evolved from a common ancestor.
The tips of the branches show the species that are still alive today. The tree also shows those that are now extinct. Darwin explained:
'From the first growth of the tree, many a limb and branch has decayed and dropped off; and these fallen branches of various sizes may represent those whole orders, families, and genera which have now no living representatives, and which are known to us only in a fossil state.'
Orders, families and genera are all groups that can be used to classify organisms.
The lines on the tree show evolutionary relationships between species. For example, a recent version of the tree of life would show a line between some types of dinosaurs and the earliest birds, as scientists reason that birds evolved from a particular lineage of dinosaurs.
This means that species that are closely related are found close together stemming from the same branch.
For example, humans, chimpanzees, gorillas and orangutans are all great apes, so they all belong to the same branch of the tree of life.
Although Darwin's theory of evolution has been modified over time, it remains fundamental to the study of the natural world. Darwin changed not only the way we see all organisms, but also the way we see ourselves.