When we think about the ‘theory of evolution’ most of us automatically think of the 19th century biologist Charles Darwin and his amazing work, ‘The origin of species’, which was published in 1859. However, some 2400 years ago, before the birth of science, Anaximander, in the Ancient Greek city of Miletus was already pondering how humans and animals had evolved.

Anaximander was the second of the great thinkers of the Milesian school, and, according to Themistius, he was the 1st of the known Greeks to publish a written document on the natural world. Sadly, only one fragment remains of his prose ‘On Nature’ in which he discussed the laws of the earth and believed that every reality can be reduced to a single unity, or in other words, ‘that all things in existence are part of the same unified oneness.’

He introduced the concept of the ‘Aperion’ – meaning infinity or boundless, undefined, and forever moving which related to nature and the universe, and he tried to observe and explain various aspects of it with a particular interest in the origins.

For instance, the world was once covered in water and as land emerged, there was a perpetual conflict between warm and cold, or moist and dry. Life emerged from this moist environment, either from the sea or the moist muddy deposits and aquatic creatures, both humans and animals began to evolve. He further theorised these marine creatures would have had an armour or shell that would break to allow them to descend onto land as this evolution took place.

His theories are said to have arisen after observing the fetus of several animals and concluding they all resembled fish, he believed that a mutation could take place if they remained in the womb for long enough. Although these theories are controversial, there are similarities to later studies and understandings of vertebrae evolution, the earliest being jawless fish which over time developed bones, vertebral column, and jaws. Further evolutions were divided into 5 groups. The order was fish, amphibians, reptiles, mammals, and birds.

According to the 3rd-century Roman – Censorinus, “Anaximander of Miletus considered that from warmed up water on earth emerged either fish or entirely fishlike animals. Inside these animals, men took form, and embryos were held prisoners until puberty, only then after these animals burst open could men and women come out, now able to feed themselves.”

He also suggested all dying things return to the element in which they came from and stated that nature was ruled by laws, if these laws are broken and the balance is disturbed, nature cannot last. It is unclear if he was referring to certain species becoming extinct or evolving due to the changing environment as Darwin observed in the Galapagos with his extensive study of finches, in which he studied a group of 18 species whose beaks had adapted into new forms depending on environmental conditions.

According to National Geographic, ‘scientific theories based on empirical evidence and rigorous testing were not the practice in Anaximander's time.’ Therefore, his theories could not be put forward as a perfectly developed scientific theory in the contemporary, modern sense. However, Anaximander’s insightful and fascinating studies were certainly way ahead of their time and helped to lay the groundwork for later scientific contemplation.

I find it extraordinary that the intellectual thinking of the philosophers of the Milesian school of thought was so inspirational so many centuries ago. It is unsurprising that their theories are still discussed today.