Although he was careful not to say directly that mankind was descended from apes, and not from Adam and Eve, the implications of his classic work On The Origin of Species were clear and caused a rumpus.
His theory of evolution through natural selection is one of the most profound contributions to science of all time which started a debate about the origins of humanity that continues to this day.
Author and evolutionary biologist Professor Richard Dawkins was to declare: “Along with Shakespeare and Newton, Darwin is our greatest gift to the world.”
Darwin has become Shrewsbury's most famous son. But his fame only came after years of agonising over whether he should release his work.
He was fully aware of how controversial his theory was likely to be, and sat on it for 20 years – for so long, in fact, that in the end there was a serious danger that he would be "scooped," because he was not the only person to be thinking along those lines, although the difference was that he had accumulated the evidence and fieldwork to lend weight and credibility to his theory.
In the event when Darwin did finally go public, his scientific peers, while impressed, did not immediately grasp how groundbreaking the theory was.
It was at the start of July, 1858, that papers by Darwin and Alfred Russel Wallace outlining the theory of evolution by natural selection were presented to the Linnean Society. Wallace had independently come up with a theory very similar to Darwin's.
Neither man was there. Darwin wasn’t feeling well, and was grieving for his 18-month-old son who had died of scarlet fever, while Wallace was abroad.
Founded in 1788, the London-based biological society is a forum for the discussion and advancement of the life sciences.
Things had been brought to a head when, on June 18, 1858, Darwin had received a letter from Wallace containing an essay called, ‘On the tendency of species to depart indefinitely from the original type’.
He was persuaded by two people familiar with his work, Scottish geologist Sir Charles Lyell and botanist and explorer Joseph Dalton Hooker, not to publish Wallace’s essay without publishing his own long-withheld manuscript.
He left it to them, and just a day before the Linnean Society meeting they wrote to the society’s secretary and arranged it.
As it was customary not to publish an agenda in advance, the papers that were read out by the secretary were a complete surprise to everybody there. They were received in silence.
An article by intern Eleanor Marshall published on the society’s website, written for the 160th anniversary of the event, says: “In a letter written from Hooker to Charles Darwin’s son, Francis Darwin, 28 years after the meeting, he describes how the room was awestruck and completely silent.
“There was a lack of discussion about the papers which he put down to the subject being too novel and ominous.
“Thomas Bell, the president of the society at the time, had no inkling that this was the start of a paradigm shift.
“In his presidential address in May 1859, reviewing the previous year, he said, ‘The year which has passed… has not, indeed, been marked by any of those striking discoveries which at once revolutionise, so to speak, the department of science on which they bear’. It was only when Darwin published his ‘Origin of Species by Means of Natural Selection’ a year later that the significance of this momentous occasion became evident.”
It was because Darwin’s theory was backed up by his book, the title of which is usually simplified to On The Origin of Species, and an immense body of work going back many years, that he, rather than Wallace, was recognised as the father of the theory of evolution, and became a household name.
The book caused both great interest and great controversy, being a challenge for the Church and Victorian society generally.
Its implication that humans are descended from apes was hard to take. Yet it was a bestseller and Darwin, who had been worried sick about the reaction – as early as 1844 he had compared his ideas to confessing to a murder – was emboldened to expand on his theories with the book, The Descent of Man, in 1871.
In a 1998 interview John Thackray, archivist at the Natural History Museum, said that Darwin's Origins book was quite shocking.
“Darwin was ill for most of the second half of his life and there’s a theory that this was really an anxiety-related illness. He was so worried about how his theory was going to be received and whether he would be personally subject to ridicule and abuse. He said it was like confessing a murder.”
The outcry was not just from the Church. Many scientists savaged it. But gradually his ideas gained acceptance, and according to Mr Thackray, Darwin is a "towering figure."
Darwin was the son of a successful Shrewsbury doctor and the eldest daughter of Josiah Wedgwood, of pottery firm fame. They were one of the wealthiest families in the town and lived at The Mount where Charles was born in 1809.
The Mount was to stay in the Darwin family until 1866, although Charles himself moved to Down House, Kent, in 1842.
Charles first attended a day school run at the home of a Unitarian minister in Claremont Hill before going to Shrewsbury School – then housed in the building which is now the town’s library – as a boarder.
From an early age he was a keen collector of such things as beetles and moths. His father Robert wanted him to follow him into medicine, but Charles’ heart wasn’t in it. Then the idea was that he would become a country parson.
Yet his interest in natural history burgeoned while studying for the Church at Cambridge and led to him being offered a place as the "gentleman naturalist" on the Beagle, a 90ft long navy vessel which was to survey the South American coast.
The five year voyage was to change his life – and ultimately our view of the world.
Darwin, who was in his early 20s, was in his element, riding great distances inland, climbing mountains, digging for fossils and collecting plant and animal life.
He was universally liked and respected by the crew.
His fieldwork made his name and his discoveries laid the foundations for him to formulate his famous theory on his return.
During the exploratory 1830s voyage around South America, Australia, New Zealand and the South Pacific he sent home 1,529 species preserved in spirit and 3,907 labelled skins, bones and other dried specimens.
One specimen comprised the leftovers of his 1833 Christmas dinner, in which he had accidentally eaten a new bird species.
The remains, which were preserved and sent home as soon as he realised the mistake, were later named after him as the lesser rhea – Rhea darwinii.
Such scientific curiosity and attention to detail meant that by the time Darwin published his theory he was a highly respected scientist who had collected a mass of evidence with which to back up his ideas.
His father was wealthy and supportive, which meant Charles could devote himself to his studies without financial worry.
Mr Thackray said: “You tend to think of him as rather a frail old man with a long white beard sitting in the study at Down House falling ill, but he was also a very energetic young man who lived in Shrewsbury and went around the world on board the Beagle with his hammer doing lots of fieldwork. Too often we think of him as this geriatric old man, which is a great pity.”
On a return visit to Shrewsbury in 1866, Darwin’s presence did not create a stir, and Darwin expert Henri Quinn thinks part of that was because he had alienated the Church, and Shrewsbury was very much a Church town, and also his father was a big money lender, the two things together not making the Darwins very popular locally.
He also believes biographers have paid too little attention to the fact that Darwin was already formulating his ideas when he lived in Shrewsbury.
For instance, he had been told the world was about 6,000 years old, but the bellstone – a large glacial rock in front of the Morris Hall – showed him that it was much more ancient.
Darwin was to see tragedy in his personal life, as three of his 10 children died before adulthood. Their deaths and illnesses of the others prompted him to fret that inbreeding – the result of his marrying his first cousin – was to blame.
On January 29, 1839, he had married Emma Wedgwood.
Darwin had put some thought into the decision to wed. He compiled a list of the advantages and disadvantages, concluding that a woman would be a better companion than a dog in his old age.
While at Down House he designed a wormograph (“the Worm Stone”) to measure the effects of worms on the level of soil in the house’s garden. He also kept worms in pots of earth in his study to observe their reaction to different sounds, including the bassoon.
The family kept horses, cows, pigs and poultry, and Darwin studied domestic pigeons to provide evidence for his theory of evolution by natural selection, building a pigeon house in his garden in 1885.
Darwin did not get everything right, and his theory of "pangenesis," which tried to explain the variation in traits from one individual to the next in a single species, is considered to be mistaken.
For many years Shrewsbury was accused of not making enough of its Darwin links, who was commemorated in the town by a shopping centre, a pub and a couple of statues.
However, there have been assiduous efforts in more recent times to put that right. And one of the results was the advent of a Darwin Festival, which began modestly with a week-long event in the town in 2003, and in February 2004 for the first time an entire month was devoted to celebrating the great scientist and naturalist.
Among new tributes was the Darwin Gate at Mardol Head, said to have been the first public sculpture of its kind since 1897, which was unveiled on November 24, 2004.
Designed as a monument to Darwin, it beat more than 100 entrants to win a national competition run by Shrewsbury and Atcham Borough Council.
And on October 8, 2009, the Quantum Leap sculpture by the riverside was officially unveiled by the great-great-grandson of Darwin, Randal Keynes, to mark Darwin’s bicentenary.
There was a small protest at the ceremony over the cost, which at the time was put at £450,000 but turned out in the end to be over £1 million, which meant it had cost more than the Angel of the North (£800,000).
The statue of a seated Darwin outside the town's library, which was formerly Shrewsbury School which he attended, dates from 1897.
Incidentally Darwin appears so far not to have attracted the attention of the statue-topplers, although some things he wrote would not go down well in print today.
Nationally, Darwin beat off stiff competition from author Charles Dickens to become the face of the new £10 note in 2000.
Although the public image of him is of a bearded man, he didn’t start growing his famous beard until 1862, following a period of poor health.
On his death on April 19, 1882, he was given a state funeral. He is buried in Westminster Abbey.