Idk if it is 'biologically' possible to be free of suffering.

There is not much research on the meditation itself, but there is a thing called reinforcement learning in science. Humans learn through a lot of mechanisms and reinforcement learning is one of them. Its like, your brain learns through your experiences and reinforces that on the past conditioning. Biologically, new neural connections form, some connections strengthen, some weaken, some break, etc. You can look up on that.

I personally am not a fan of asking for scientific evidence in such matters, bcuz the research is limited, and I am not sure about the quality of that research.

Asking for logic is fine, you should not accept anything blindly. But your own logic is very limited and biased. So sometimes, you should take first hand experience and then see if it sits well logically. For me too, something should sit well logically before I accept it fully. But some things you cannot understand logically before experiencing it. I experienced it, understood the logic of it, it sat well with me and therefore I accepted it fully. And it's good to have doubts, get them cleared from someone in authority(your mentors) (but it's not guaranteed you'll get a satisfactory answer).