Age of Consent for Marriage - From Journal of Psychology
...Age of Consent throughout history has usually coincided with the age of puberty although at sometimes it has been as early as seven...
...The Roman tradition served as the base for Christian Europe as well as the Christian Church itself which generally, essentially based upon biological development, set it at 12 or 14 but continued to set the absolute minimum at seven....
Ayesha was 9 when the marriage took place. Prophet Muhammed married Ayesha with her permission after she attained puberty at the age of 9.Puberty is a biological sign which shows that a women is capable of bearing children. Can anyone logically deny this? This is certainly not something that Islam invented,this has been the norm of cultures and nations.Today the civilized world considers same sex marriage perfectly legal so it is no wonder the natural bilogical permission for marriage seems to belong -primitive societies.
As to his alleged old age (he was the commander in chief of his army not a shabby saint with hanging skin).You should know Prophet-s marriage to Aishah was an exceedingly happy one for both of them.If you couple this with the fact that attaining the age of puberty varies with countries and races due to the climate, hereditary, physical and social conditions, you wouldnt be asking this question.