"Niche
"a. A situation or activity specially suited to a person's interests, abilities, or nature: found her niche in life.
is held by regional magazines" (Brad Edmondson).
4. Ecology
a. The function or position of an organism or population within an ecological community.
b. The particular area within a habitat occupied by an organism."
Natural & unnatural to us: To which we have inharent sense of right & wrong and to which we don't have. Since unnatural to us, can cause confused or shocking effects, our body may not be able to process those normally or as pre-informes & pre-prepared.
Losing natural environmental factors or innate immunity is one thought, loosing stem cell niche, the other. Due to it, medical interventions & stem cell therapies are needed & popping up on big scale.