My floor joists are bowing

[Ken AP]

Hello all! I recently purchased a home and have noticed that the floor joists in my basement are bowing. Actually, I'm not sure if bowing is the correct word. The joists seem straight length-wise. However, they are curved vertically where they come to rest on a metal support beam in the middle of the house. I have attached some pics of the joists.

This is a 50 year old house. Should I be concerned by this? Is there a way to fix it?

Thanks!

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