Pigs undoubtedly have a better sense of smell than us, but it's unclear if it's really "better" than dogs. Pigs in truffle hunting is a bit of a misconception. Wild boars might be able to find them sometimes, but the best truffle hunters are dogs. In attempts to quantify "sense of smell" pigs ranked lower than mice and way lower than elephants.
So, no, I don't think the large brain is to do with smell. I think it's more to do with them being quite similar to us which is apparent if you ever encountered a pig. What people do to them is horrible and they don't deserve it.
Acknowledging that my own reading of the situation may be flawed, I'd though the situation was that pigs on average are better at sniffing out truffles, but dogs are the better truffle hunters on account of being "good enough" and the fact that dogs, unlike pigs, aren't going to eat half the truffles they find.
No one here seems to have any idea what they are talking about about. 1. You put a ring in the pig nose so it doesn't root and eat the truffles, 2. Dogs have a better sense of smells than pigs by a lot, 3. Big brains don't come from standing upright, whales and dolphins have larger brains, 3. Brain size is important for intelligence, almost always the larger brain the more intelligent, the whole nonsense of body to brain ratio be more important was to make half the human population not feel as bad about having smaller brains. Almost always, more brain == more smart.
> 3. Big brains don't come from standing upright, whales and dolphins have larger brains
That is a terrible "counterexample" to the idea that it's easier to balance a large brain on top of a spinal column than to support it as it sticks out in front of the animal. Whales are aquatic; every part of their body is supported by the water.
So, no, I don't think the large brain is to do with smell. I think it's more to do with them being quite similar to us which is apparent if you ever encountered a pig. What people do to them is horrible and they don't deserve it.