[Modernman]

"Adam" could be a person of special importance and his bones could have been taken to Africa as a sign of reverance!

Sure, but there's no way to determine whether that is true or not. Most likely, not. People of the time were hunter-gatherers who travelled with nothing but what they could carry.

[CobaltBlue]

The DNA studies don't use bones. Certainly not for Y-chromosome DNA, it doesn't last long enough.

They've got ever larger pools of DNA from living people, and they use models of genetic drift to estimate the time it must have taken for the changes which they can see to have occurred. So if you want to reject the theory, the only thing that can be rejected is the timeline. That is the only guesstimate.