why did it took several centuries before the civilizations of the two hemispheres had communication??

Due to lack of technology.

Explanation:

It took several centuries before the civilizations of the two hemispheres had communication because of lack of technologies that can make a bridge of communication between two hemisphere. People are not interested in research and having old wrong beliefs that prevent them from growth and development but due to renaissance movement people get rid of false and wrong beliefs and work for the advancement of technology which leads to communication between two hemisphere.

the biopsychosocial approach was developed at rochester decades ago by drs. the biopsychosocial approach systematically considers biological, psychological, and social factors and their complex interactions in understanding health, illness, and health care delivery.

explanation:

i have to go with a for this one