Naturalist :  (noun)
1: an advocate of the doctrine that the world can be understood in scientific terms
2: a biologist knowledgeable about natural history (especially botany and zoology) [syn: natural scientist]

Marxist, anatomist, bacteriologist, biochemist, biologist, biometrist, biophysicist, botanist, commonsense philosopher, cytologist, dialectical materialist, ecologist, epistemological realist, geneticist, materialist, natural realist, natural scientist, physicist, physiologist, realist, zoologist,