Wall construction

[Robkarlee]

I have a 1944 English Tudor home that is a story and a half. The front of the house faces north.

It has a support beam which runs east and west down the middle of the basement. The distance is approximately 60 feet. The house is approximately 25 feet wide. The joists are running north and south.

Under each main floor wall there is a joist with blocking then another joist. In essence what I have under each main floor wall is a 2 x 8, next to a 2 x 8, with 2 x 4 blocking between them. Are these walls load bearing walls? There are no walls above these walls running parallel to these walls on the second floor. Everything appears to be landing on the main support beam running east and west, down the middle.

I hope I have made this clear. I've added a picture to show the construction of the underside of the wall.
Does anyone know what the purpose of laying out floor joists in this manner is?

Thanks to any who can help with info!!!