Has Neville’s experience with fear caused him to lose his humanity? How do his experiences correspond with or contradict what experts say about the effects of fear on our personalities?

Has Neville’s experience with fear caused him to lose his humanity? How do his experiences correspond with or contradict what experts say about the effects of fear on our personalities?
How does living with fear heighten Neville’s good or bad characteristics? How does this correspond with or contradict what experts say about the effects of fear on our personalities?
At different points in the book, Neville considers faith, science, the wisdom of authorities, and other things as means of solving his problems. Among these possible solutions, do any actually help him? If so, what point is the text making about the way these types of “solutions” could affect people living with fears in the real world? Do expert opinions you have read agree or disagree with this outlook?