请教一个句子

锦城碎叶

When i reviewed OG for the second time, a sentence confused me, which is in the passage called AGRESSION and about Darwin's evolution theory.

"Darwin held that many more individuals are produced than can find food and service into adulthood" , what baffled me was the usage of the very word "than" here, though i know it must be related to "more", however, it seems to be kind of logical flaw. Can, therefore, anyone parse the sentence and translate it?

There is also a question for the sentence in OG, that is, " what reason should humen survive for?" , and the correct answer is " Many more individuals are born than can survive until the age of reproduction", which is also of the same pattern as the one above.

A lot of thanks!!!!!