May 22, 1826 marks the first voyage of one of the most important ships in history, the HMS Beagle. The Beagle and the HMS Adventure departed together on a several-year long mission to Patagonia and Tierra del Fuego to conduct hydrographic survey, which involves measurement and description of the ocean and coastal regions. Like regular surveying, hydrographic surveying requires trigonometry and precise calculations. This task was difficult in the 19th century, especially on top of the challenge of navigation. The Straight of Magellan, off of the coast of Tierra del Fuego, is one of the most important but dangerous water passages in the world. In the weeks of surveying this especially difficult area, Captain Pringle Stokes went into a long phase of depression, ending in his suicide. He was replaced by Robert FitzRoy.

After his success on the first voyage, FitzRoy was put in charge of the Beagle’s second voyage, which departed in late 1831. On the first voyage, FitzRoy had wanted an expert on geology, so for the second, he decided to “endeavor to carry out a person qualified to examine the land; while the officers, and myself, would attend to hydrography”. He wanted a naturalist to go on land to learn about the geology. He had the additional requirement that the naturalist be someone that would make him a good companion. FitzRoy’s friend, Dr. John Henslow sent a letter to someone he thought might fulfill the position. The letter read,

“…that I consider you to be the best qualified person I know of who is likely to undertake such a situation— I state this not on the supposition of yr. being a finished Naturalist, but as amply qualified for collecting, observing, & noting any thing worthy to be noted in Natural History. Peacock has the appointment at his disposal & if he can not find a man willing to take the office, the opportunity will probably be lost— Capt. F. wants a man (I understand) more as a companion than a mere collector & would not take any one however good a Naturalist who was not recommended to him likewise as a gentleman. … there never was a finer chance for a man of zeal & spirit… Don’t put on any modest doubts or fears about your disqualifications for I assure you I think you are the very man they are in search of.”

The letter was to Charles Darwin. You know the rest of the story.

But what if Charles Babbage had completed his difference engine before all of this? He originally proposed his idea to the Royal Astronomical Society in 1822. Assume that everything ran smoothly and the invention was completed by 1828. The difference engine would have been able to quickly, cheaply, and accurately produce important trigonometric tables that would have been hugely beneficial to navigation and hydrographic surveying. In this case, the first voyage of the Beagle could have run much more efficiently and Captain Stokes could have enjoyed a relaxing trip to Tierra del Fuego instead of shooting himself in his cabin. Robert FitzRoy wouldn’t have taken over as captain so he wouldn’t have requested a naturalist/companion for his next voyage, and Darwin would not have been on board. He would have continued his plan of become a priest instead of writing one of the most influential works of all time.

So what if Darwin had never written “On the Origin of Species”? It’s fair to assume that the theory of evolution through natural selection would still have become scientifically accepted, since Darwin was not the first or only person to suggest it. However, Darwin was by far the most convincing, thorough, and methodically correct of the early proponents of evolution. “On the Origin of Species” laid important groundwork not only in evolution, but all life sciences, because of its strong use of the hypothetico-deductive method. Prior to this, naturalists would mostly just describe, name, and study the anatomy of species. Darwin used reasoning, analogy, and large amounts of evidence to form his “long argument”, which laid new foundations for the scientific method in biology. It was well-devised and argued strongly, making it an extremely persuasive work that inspired the evolutionary movement and exemplified proper scientific methodology. Without Darwin, natural selection would have been years behind, as would the foundations of biological research in general. This is perhaps what would have happened if Babbage had finished his machine and vastly improved the availability of accurate trig tables for celestial navigation and surveying.

But luckily Babbage never finished his engine…