On 24 November 1859, Charles Darwin’s book On the Origin of Species, containing one of the most influential ideas in the history of science, was published.
The work outlined and is now synonymous with the hugely influential theory of natural selection, which is now the widely accepted in biology and by the scientific community as a way of explaining how complex life and humans evolved.
In addition, the inherent contradictions between Darwin’s theories and orthodox Christian beliefs helped create the great debate between religion and science which raged since the publication of Darwin’s tract.
This debate reached a famous climax in the Scopes Trial of 1925, and while a scientific approach to knowledge is in ascendance now, the debate still occurs today on a smaller level.
Although evolutionary ideas had been tentatively put forward throughout the first half of the 19th century, the scientific community’s close ties with the Anglican Church of England made it hard for them to gain much credence.
The natural theology of the church taught that species were fixed and part of God’s ordained hierarchy, and that man was made in the image of God and therefore quite separate from the rest of animal life.
An unwillingness to challenge these teachings did not change until a young Cambridge graduate called Charles Darwin began his research.
The young scientist was no atheist crusader against the ignorance of the church, and had even made some anti-evolutionary arguments in papers while at Cambridge.
However, he had a keen interest in science and biology, having enrolled at medical school in Edinburgh before going to Cambridge to study the natural sciences and geology.
Voyage on the Beagle
In December 1831 Darwin volunteered to join on the HMS Beagle military and scientific expedition, which spent a lot of time in South America. It was there the young naturalist studied the fossils of long-extinct animals, and was surprised to find that they closely resembled living species on the continent.
This discovery shook his belief in the fixed nature of species, as it seemed likely that the extinct animals had somehow evolved into the living ones, creating a new but similar species.
The expedition continued for five years, and as it went on, Darwin collected more data which seemed to support his new idea, most famously observing that on three different Galapagos islands three different species of mockingbirds had evolved, each with subtle differences which seemed to suit that particular island.
When he finally returned home in 1836 he sought scientific opinion on what he had discovered, and it was confirmed that the fossils he had brought back from South America were indeed related to the Rhea, a large indigenous bird.
With many of the hallmarks of his theory now in place, Darwin took the unorthodox step of consulting animal breeders for their opinions, and was struck by the strikingly human behaviour and appearance of an orangutan he saw in the zoo.
Over the following decades, Darwin spent his time collecting and amassing a huge amount of evidence and case studies that he could use to support his budding theory.
By 1856 it was sophisticated, well-supported and comprehensively outlined in a long essay. Modern biologist Ernst Mayr summarises the key points as follows:
- Every species is fertile enough that if all offspring survived to reproduce the population would grow.
- Despite periodic fluctuations, populations remain roughly the same size.
- Resources such as food are limited and are relatively stable over time.
- A struggle for survival ensues.
- Individuals in a population vary significantly from one another.
- Much of this variation is heritable.
- Individuals less suited to the environment are less likely to survive and less likely to reproduce; individuals more suited to the environment are more likely to survive and more likely to reproduce and leave their heritable traits to future generations, which produces the process of natural selection.
- This slowly effected process results in populations changing to adapt to their environments, and ultimately, these variations accumulate over time to form new species
In 1855, Darwin received a letter telling him of another biologist – Alfred Russel Wallace – was onto a very similar theory which he called the “introduction” of species, and urging him to publish his works before the theory became associated with his competitor.
Over the next years he was in contact with Wallace, and they collaborated on some papers together, but Darwin was determined to get his theory out first, setting himself a target of five years to perfect his theory.
Publication and reaction
Finally, in November 1859, On the Origin of Species was published to great international interest.
Famously, it immediately came under attack from conservatives and Christians due to the theory’s inherent contradictions with religious teachings, and Darwin was widely derided for suggesting that humans and apes might share a common ancestry.
However, the now middle-aged scientist was a respected name in learned circles, allowing his work to be taken seriously, and by the 1870s his “evolutionism” had conclusively won the scientific community round.
The rest of the world would take a bit longer.
Today, however, faith in Darwinism is almost universal. Despite a backlash against it in the early 20th century, new discoveries, such as DNA, made alternative theories untenable.
Many of the most important fields of applied science today, from genetic mutation to vaccination, relied on the theory of natural selection for their inception, and it continues to be the foundation of all modern life sciences.
Darwin’s theories have made church teachings seem outdated, and this may have contributed to the increasing secularisation of western Europe.
Charles Darwin died peacefully in 1882, surrounded by his family.
Header image credit: Charles Darwin, from a photograph by Elliott & Fry. Credit: Library of Congress / Commons.