Here we have yet another case in which a discovery was possible for a long time before it was actually accepted. Aristotle is the villain here: he clearly endorses spontaneous generation of many plants and animals. On the other hand, I don’t remember him saying that people should accept all of his conclusions uncritically and without further experimentation for the next couple of thousand years, which is what happened. So maybe we’re all guilty.
Real progress on this question only shows up in the 17th century, with Harvey’s slogan “omnia ex ovo” and Francisco Redi’s experiments on the origin of maggots. In the 18th century, Needham’s and Spallanzani’s experiments with boiled broths further discredited abiogeneis, but the issue was not settled until Pasteur found a way of exposing boiled broths to pure air in 1859.
Part of the funny here (not even counting practical experience) is that almost every educated man over these two millennia had read, and indeed studied deeply, a work with a fairly clear statement of the actual fly->egg->maggot->fly process. As I as I can tell, only one person (Redi) seems to have picked up on this.
“But the more Achilles gazed, the greater rose his desire for vengeance, and his eyes flashed terribly, like coals beneath his lids, as he lifted the god’s marvellous gifts and exulted. When he had looked his fill on their splendour, he spoke to Thetis winged words; ‘Mother, the god grants me a gift fit for the immortals, such as no mortal smith could fashion. Now I shall arm myself for war. Yet I fear lest flies infest the wounds the bronze blades made, and maggots breed in the corpse of brave Patroclus, and now his life is fled, rot the flesh, and disfigure all his body.’ ”
You’d think a blind man would have noticed this.
Anyhow, the lesson is clear. Low hanging fruit can persist for a long time if the conventional wisdom is wrong – and sometimes it is.