Because it has no scientific explanation. As a matter of fact it has no explanation.
The things that black cats cause bad luck are a myth, and do not have any proof or explanation, meaning it cannot be concluded neither as a hypothesis nor scientific.
Hope it helped,
BioTeacher101
Salutations!
What is the skull mainly composed of how many cranium?
The skull is composed of eight cranial bones (cranium). Cranial bone is the bone that protects the top part of the brain. If we are generally speaking, the skull consists of 22 bones.
Hope I helped (:
Have a great day!