Spontaneous Generation - Pre-Aristotelian Philosophers

Pre-Aristotelian Philosophers

As part of his overall attempt to give natural explanations of things that had previously been ascribed to the agency of the gods, Anaximander believed that everything arose out of the elemental nature of the universe, which he called the "apeiron" or "unbounded". According to Hippolytus of Rome in the third century CE, Anaximander claimed that living creatures were first formed in the "wet" when acted on by the Sun, and that they were different then than they are now. For example, he claimed humans, in a different form, must have earlier been born mature like other animals, or they would not have survived. Anaximander also claimed that spontaneous generation continued to this day, with aquatic forms being produced directly from lifeless matter.

Anaximenes, a pupil of Anaximander, thought that air was the element that imparted life, motion and thought, and speculated that there was a primordial terrestrial slime, a mixture of earth and water, which when combined with the sun's heat formed plants, animals and human beings directly.

Xenophanes traced the origin of man back to the transitional period between the fluid stage of the earth and the formation of land. He too held to a spontaneous generation of fully formed plants and animals under the influence of the sun.

Empedocles accepted the spontaneous generation of life, but held that there had to be trials of combinations of parts of animals that spontaneously arose. Successful combinations formed the species we now see, unsuccessful forms failed to reproduce.

Anaxagoras also adopted a terrestrial slime account, although he thought that the seeds of plants existed in the air from the beginning, and of animals in the aether.