He is an expert in malacology, focusing particularly on the study of snails.

He is majoring in analysis at university.

He is an expert in paleontology.

He is an expert in paleoanthropology, conducting research on the origins of mankind.

I love histology classes.

That theory is unscientific and has no evidence at all.

He is an expert in astrophysics.

He is majoring in belles-lettres.

She is majoring in clinical psychology.

He lost his sense of direction.