Oh my word.. I have no idea. How do you know they can’t!! I keep hearing a rumour that dogs also can’t look up.. I think for this you have to consider why they would have to look up! In both cases, of pigs and dogs, I think neither creature has a wild predator which would attack from above..
But if they really cannot, it is usually because of the shape and position of the spine. Even humans can’t look all the way up in one move. To see right above you, you need to look up AND you need to bend your back, to look directly up. So maybe no animals can truly look physically up in one movement, and whilst pigs cannot do this at all (because they always walk on four legs), dogs can in theory look up because they can rear up and stand up on two legs, meaning they can bend their back like humans, I guess!
I heard this quote a long time ago which I think is funny:
“I like pigs. Dogs look up to us. Cats look down on us. Pigs treat us as equals.”
Daz is right. It’s all got to do with their spines and the conformation of thir bodies. Pigs have very short necks so they find it very had to look up at the sky. Remember they also have their eyes at the side of their heads. So now, quick experiment:
Scrunch you head down to your shoulders, making your neck as short as possible. Now try look up. How much do you see? Now, imagine how much you would see if your eyes weren’t in the front but on the side of your head? Not very much right? Now if possible (better ask your teachers permission if you’re at school!), go down on all fours (like a pig) and do your piggy neck again. Do you see any better? How about if you pushed your weight back into your bum a bit so your ‘front legs’ were really stretched. Can you see more now?
I hope this helps you answer your question, and gives you a bit of a laugh trying to do the experiment! So I think the answer is that pigs can look up, but not in the same way we do, and can’t see as well as we do either……but nothing from the sky is really going to hurt them so maybe that’s why they’ve developed to see better at ground level!