Hardwood floors? I just moved into a completely old house and it have hardwood...

I just moved into a completely old house and it have hardwood floors. Over time the stuff between each board have came out. This must enjoy been done surrounded by a time when builders couldnt get strait boards and have to fill surrounded by the 1/8 to 1/2 inch cracks. I can feel cold nouns coming through the now unseal cracks. What can I use to re-fill the joints that would be correct, as this is a rental house? I already know caulk is not the answer.
Water Hammer?
Answers:    I enjoy the entire upstairs of my old house near gaps that are mostly 1/16 or more. It be a squeaky mess. In one closet cold air poured thru the cracks. The floor be a single boards about 3 inches cavernous nailed to the floor joist directly, no sub floor.

My fix was to sand the floor room beside a rented sander from Home Depot, the kind beside 4 revolving heads. Then I vacuumed and cleaned joint best as I could.

Then I bought a 5 gallon can of Epoxy TWO PART floor sealer, the kind used within garage floors. I got the clear coat benign and mixed it with the hardener one pint to a gallon as directed. Then I took a regular floor applicator squeegee and applied the coating.

The Epoxy clear coat sunk into the grooves and hermetic them. It took 2 coats of this stuff to make a really right finish floor and seal those cracks up. The cost is more or less $65 for a 5 gallon can of Epoxy floor sealer and it goes a long channel.

Gone are the squeaks and leaking nouns.
Stop paragon sea filter nouns from spraying...
I would think you could basically have them resealed and that would work.