"The world's population"
Translation:La población mundial
At the end of the day the criterion for a good translation is what a native speaker of the target language would say when needing to express the same concept as that expressed in the original language.
And it happens to be the case that this English version and this Spanish version happen to be the most common means of expressing the relevant concept. Certainly didn't know this before, but I was curious why the grammar didn't match myself.