Nothing would happen. Humans ARE animals.
They would die.
Then only the lesson mathematics would be taught on that day.
we would die
The same thing that would happen to humans if we had no food.
then you would not even be here
we would not be able to walk
we couldnt see
There would be no mathematics and so no science or technology and so no computers through which you could ask this question.
Many would die.
we would all be eaten by flies
Humans are already animals, being part of the animal kingdom. Therefore, what would happen is that we would carry on as usual.