I have always found the standard versions of the origin and early years of Rome to be a bit murky. Also, as it grew, there appears to be precious little research into the demographic changes which must have taken place.
Looks like there are some new studies being done. Here are popular summations. Can anyone get their hand on the actual studies and break it down for us nonscientists.
I am aware that the popular press usually leaves out all the good stuff and real info.