Are1/8" gaps in 65-70 year old Oak Hardwood normal?

I have this house that I'm looking to buy and I noticed the floors are squeaky, fine, but there are a lot of boards with gaps. The house has been vacant for a few months so I imagine they moved because of the humidity, but is that much movement normal? Is there anything to do about it? I'd be willing to sand and refinish if it helps.

Photo here: https://imgur.com/a/n1lygpR