The Age of Maturity in Comparative Jurisprudence; Religious Sign or Natural Sign

There are some signs for recognition of a mature person, although some of them such as the age itself is not accepted by some and caused dispute among jurisprudents. Basically, Some Sunnis’ scholars have not considered the age as a sign of maturity and have mentioned the other marks. In contrary, some have counted several ages for the maturity in the absence of the other signs.
       This disagreement about the age can be found in Shiite jurisprudence too. Predecessors believed that the age is the sign of maturity because of the traditions and have appointed nine years for a daughter and fifteen years for a son. This view was so dominant on their thought and their Islamic verdicts that few persons could criticize it explicitly. Nevertheless, it may be found some views among their words that itself indicating that this sign was not
accepted unanimously.
     Today, contemporaries in regard to the circumstances of time and place have studied the ideas of the predecessors critically and have doubted about its trueness. In accordance to their view, a natural phenomenon which is different in various people due to diverse factors, how can a criterion (9, 15) be counted as a sign of maturity? Furthermore, how can we expect from a nine years daughter who has not mental bodily development to do her religious tasks?
     Now the question is that is the age the sign of maturity? Can we regard it as a religious sign? And finally what sign or signs are there for maturity and must be a basis for action?