Hypothesis is an assumption which is made before any research has been done. hypothesis is formed so that it can be tested to see if it is true.
A character which has been lost in a breed and it reappears after a great number of generations, the most probable hypothesis is not that the offsprings are suddenly takes after an ancestor but some hundred generations distant, but that in each successive generation there is some tendency to reproduce the character in question, which at last under unknown favourable conditions, gains an ascendancy