I don't think there's a good enough understanding of genetics to know how many generations. I'm guessing the estimate of a few thousand years was a complete gue

I don't think there's a good enough understanding of genetics to know how many generations. I'm guessing the estimate of a few thousand years was a complete guess. Many things impact the timing and these systems are chaotic. Even selective breeding is fairly uncertain. I don't know if geneticists could predict how many generations it would take if we selectively breed gray wolves to look like pugs.