Darwin’s era was not the first time that people began wondering where humans come from. Throughout history the debate is one, and the side arguing against pure creationism (though not necessarily against theism) has been stymied by the old “chicken and egg” question. You can’t get an adult without raising it from a baby, and you can’t get a baby without an adult. How to get out of that cycle?
One of the first to come up with a fact-based solution to this was Anaximander – a Greek philosopher born around 610 BC. Granted, it was the wrong solution, but what could he do? It took a lot of background research to come up with the theory of evolution by natural selection, and he lived roughly 2,500 years before any of it happened.
Anaximander believed in a progression of animal forms, and that “humans were born from other kinds of animals.” He went too literal with his interpretation of “born,” but to be fair to him, he did so because he followed the evidence. Anaximander was observational, and one of the things he observed was fetal development. At a time when people still lived in close contact with the animals they ate, this wasn’t so unusual. He had the ability to look at fetal, or still-developing, mammals, birds, and fish. It also appears that he had some experience looking at human fetuses in early stages of development. To Anaximander, the earliest stage of fetal development, in any animal, looked like an early developing fish. If something gestated long enough, he reasoned, it could grow into all kinds of things.
Read full, original article: The First Theory of Evolution Involved Fish People