Anyway I once read a part where Betrand Russell claim that the reason why some of the renaissance and modern philosophers didnt reveal their disbelief is because they didnt want to lose their job or patronage, i wonder if its the same with the Muslim philosophers back then.
Well it was not just about losing patronage, but also losing your head. In medieval Islamic societies, the crime of apostasy was punished by death.
On Ibn Khaldun, I have never read that before. So thnx for posting. Though I do not think it is quite "evolution", as there is no identification given for the mechanism by which species evolve. I.e. no explanation of the process of natural selection and the survival of species best adapted to suit their environment.
In fact, your quote from Ibn Khaldun sounds pretty similar to the dominant view held in the West since the Classical period developed by Plato and Aristotle known as the "Great Chain of Being
". Though it is striking that Ibn Khaldun specifically notes that monkeys are the closest animal to humans on the chain.
I have always wondered why it took so long for humans to understand evolution as it just seems so obvious to us today. Humans have been using the basic concepts of evolution in selective breeding with domestic animals since the dawn of agriculture so it is not much of a leap from understanding those prinicipals to finally working out the whole process of speciation.
I think that the Abrahamic Faiths probably suppressed a lot of inquiry into these areas, but that does not explain why the Ancient Greeks or the Ancient Chinese never figured it out. My guess is that those societies were not well traveled enough and had not yet collected enough samples of various animals to see the wider picture.