Chin Raising?

[Swissgreys]

I have looked at a few behavioral threads, and am still confused about this particular behavior.

As all three of our piggies reach sexual maturity, there have been a few more scrabbles and altercations.
Nothing serious - just lots of gesturing and strutting.

But the one thing I see a lot is chin lifting.
One pig will approach another, and then one of them clearly lifts their chin.
Is the chin lifter displaying dominance or submission?

It's not really important as they all get along great on a daily basis and still sleep in a small pile together.
I'm just curious, as I find their general dynamic fascinating.

 

[Beans&Toast]

My two do this sometimes and I was under the impression that it's a dominance thing.. almost like a stand off? Whoever lifts their head the highest and stays the longest is the "winner"..