[Biassasecumma]

Sorry to bother you, but what is LaMarckian evolution? is it againt Islamic beliefs?

That was just an anecdote. Evolution has no relation to the issue of beliefs unless one disbelieves in the creation of Adam and Eve as Allah tells us which Ibn Khaldun obviously does not do.

Darwinian evolution is based around the idea of natural selection. That is, mutations develop, and mutations that lead to beneficial traits are passed on. This has the most support today.

LaMarckism is based on the idea that species develop traits in response to the environment or in order to adapt, and then these are passed on. Like... let's say moths colored black have an advantage over moths colored white. LaMarckism would be to think that the moths developed the black color trait in response to this and passed that on. Natural selection as explained in Darwinian evolution (or modern evolutionary theory which isn't really Darwinian anymore but descended from it) says that mutations develop all the time, for almost random reasons (not random, but due to genetic processes... mutations develop all the time in populations), and beneficial mutations that happen to develop are passed on, and detrimental mutations are weeded out (those organisms don't reproduce).

Though LaMarckism is incorrect, that Ibn Khaldun came up with it before LaMarck at the time he did is pretty extraordinary. It was an incorrect theory of evolution, but a theory of evolutionary processes nonetheless. Westerners hold him in awe. When I sometimes get into debates or discussions with Westerners on this matter, I use him to illustrate the contributions to science of Ash'ari scholars. They were no less brilliant and innovative than Mutazilah (whom the Westerners love for more sinister and divisive reasons).

Westerners also misinterpret his writings to say that he says humans came from the world of monkeys, but that is not what he said. The passages from the Muqaddimah quoted on Wikipedia:

This world with all the created things in it has a certain order and solid construction. It shows nexuses between causes and things caused, combinations of some parts of creation with others, and transformations of some existent things into others, in a pattern that is both remarkable and endless.

One should then take a look at the world of creation. It started out from the minerals and progressed, in an ingenious, gradual manner, to plants and animals. The last stage of minerals is connected with the first stage of plants, such as herbs and seedless plants. The last stage of plants, such as palms and vines, is connected with the first stage of animals, such as snails and shellfish which have only the power of touch. The word 'connection' with regard to these created things means that the last stage of each group is fully prepared to become the first stage of the newest group.

The animal world then widens, its species become numerous, and, in a gradual process of creation, it finally leads to man, who is able to think and reflect. The higher stage of man is reached from the world of monkeys, in which both sagacity and perception are found, but which has not reached the stage of actual reflection and thinking. At this point we come to the first stage of man. This is as far as our (physical) observation extends.[48] He's basically saying life became more complex with time, and he talks about the transformations that we know are possible from Islamic scripture (Allah has transformed humans into monkeys) as the way species bridge junctions. So he has the idea of evolution in mind, but he doesn't consider it some kind of its own force. He just views it as a function of time. Naturally, over time, life became more complex and spread throughout the earth. And Allah introduced humans into the equation at the right time. Meaning, because humans were created in Heaven, it could be that Allah sent humans down at the time of the dinosaurs, when we would have been very out of place in a world dominated by non-mammals. Instead, Allah created the world with a natural order, and placed man into this order in his proper place and time.

I asked a Deobandi alim or two about him a long ways back and they had nothing notable to say. He was famous, the Muqaddimah was famous and a great book, and that was about it.