The comma before “and” (or comma before “or”) at the end of a list is optional. It’s referred to as an Oxford comma or serial comma. Most academic style guides recommend adding it (“salt, pepper, and paprika”). But it’s also not a grammatical error to write a list without it (“salt, pepper and paprika”). Some authorities, such as the AP Stylebook, do recommend leaving out the comma.
The Oxford comma tends to improve the clarity of lists, especially complex lists, by showing clearly where one list item ends and another begins. In academic writing, it’s recommended to use it.