>I know you can trace ancestry via direct line female lineage using
>mitochondrial DNA, and via direct line make lineage using the Y
>chromosome, but I didn't realize that you could trace back multiple
>generations without having the intermediate DNA profiles. I would
>think that would be somewhat difficult if you didn't have certainty a
>la the above two methods...

The more distant the relationship the less reliable this sort of thing gets, but there is enough to link out a couple of steps. You also cannot tell between a grandfather and an uncle because they have the same level of relationship.

This is with the couple of dozen sites currently used for DNA profiles. Add a few hundred years of development and you are looking at having at least a half-dozen sites on each chromosome and a much better way of flagging probable relatives.