Complex sentence: Of course, Lakoff and Núñez might correctly point out that Fermat's theorem, built on the metaphorical constructs they argue are at the root of mathematics, should surely mean the same thing for as long as our brains are constructed in the way they are.
Split into simpler sentences: Of course, Lakoff and Núñez might correctly point out that Fermat's theorem is built on the metaphorical constructs they argue are at the root of mathematics. Therefore, it should surely mean the same thing for as long as our brains are constructed in the way they are.