Interesting

He was most inspiration, apart from his theory, Dogs always release saliva before meal.

Ivan Petrovich Pavlov found that dogs responded to feeding before they were fed concluding that they were conditioned to react to their handler more so than the food it self.

This is about a learned behaviour or response to a stimulus, like when the dog sees the feeder, it represents food

Pavlov effectively demonstrated the effect of conditioning on dog salivation

Classical conditionning can also be applied on the human behavior (Consumer behaviour in Marketing)

Would the dogs have been conditioned to react on the smell of meat alone without the sound of bells?

Interesting

It can be done to human?

Dogs are traineble whatever you do with or to them per time there expect that whenever there see you you are going to do the same hence salvation whenever Ivan appears. I believe classical conditioning has to do with the sight and association there had with Ivan.