At a time when we take the search for signs of life beyond the confines of the Earth (as a scientific frontier) very seriously, it is interesting to consider a bit of the history of the concept itself. This is not entirely frivolous. The way we think about the natural world and the way we ask our questions will always be biased and guided by our preconceptions and speculations. A better appreciation of those predispositions can help us avoid obvious pitfalls.
One of the oldest recorded examples was written in 200 AD. C. by Lucian of Samosata (in eastern Turkey), a satirist and practitioner of rhetoric of Assyrian descent (it is believed). Among his works is a novel called Vera Historia, or “True History,” which details a trip to the Moon and the discovery of a multitude of life there. That lunar life includes three-headed vultures, birds made of grass with wings made of leaves, humans sweating milk, and fleas the size of elephants.
Clearly, the story is far from “true”, and Lucian made no secret that it was a fantasy. In fact, he was partly raising a philosophical question about the impossibility of real truth and the fallacy of other thinkers for claiming to be arbiters of truth, including sacred figures like Plato.
But the story is one of the oldest known in which extraterrestrial life is imagined in detail. The Moon beings are even at war with the Sun beings. Apparently, the aliens would be susceptible to our type of defects. Interestingly, the possible existence of solar life was still circulating in the late 18th and early 20th centuries thanks to astronomer William Herschel. Except Herschel wasn’t writing fantasy, he actually suspected that there could be living beings on the Sun, on a hypothetical solid surface.
The Moon has always been a good incubator of ideas about other forms of life. The 10th-century Japanese narrative (or monogatari) of The Tale of Princess Kaguya has versions in which the titular princess has been sent to Earth by the people of the Moon during a celestial war. But this story has the aliens in human form.
In fact, it’s interesting to see that since the earliest days, including the ancient Greeks’ ideas about cosmic pluralism, people have tended to assume that extraterrestrial life would be like us, or to opt for a complete, bizarre extraterrestrial treatment. Despite that division, there has mostly been a bias towards human forms, throughout the 1700s and 1800s, where writers such as Voltaire in his Micromégas have aliens from Saturn who (despite measuring six thousand feet tall) are basically human.
In reality, it wasn’t until Darwin’s theory of evolution broke through that anyone attempted to imagine aliens as living beings with lineages related to the environments of their origins. Up to this point, anything non-human was, like Lucian’s extravagant beasts of Samosata, most of the time arbitrarily fantastic.
One of the slightly more advanced thinkers was the French astronomer Camille Flammarion (although he was also a fairly staunch defender of a mixture of Christianity and pluralism in which souls passed from one planet to another). In 1864 he wrote a book titled Real and Imaginary Worlds, and in 1887 a piece of fiction called Lumen. Among these he invented extraterrestrials that, in many ways, had a basis in the scientific thinking of the time. There were intelligent plants whose digestive and respiratory systems were combined. Mermaid-like creatures swimming in pink oceans and human-like beings with extra toes on their heels and a single conical ear on the top of their head.
In all, the history of our ideas about extraterrestrial life has many anecdotes and side alleys. But one of the most surprising facts is that while we’ve been thinking about these things for a long time, we’ve really struggled to combine our imaginative fantasies with “viable” biology without simply resorting to the defaults of what we know. Land.
Evolution is a surprisingly inventive phenomenon. We could look at a planetary environment and propose what kinds of strategies life might adopt, but beyond the basic function (using sunlight, for example, or exploiting reducing and oxidizing chemistry), we guess what tricks and quirks life is going to experience. Life is extremely difficult.