FTDNA have just released a tool to indicate the matches of your autosomal DNA with the MyOrigins reference populations.

It seems that this can be used to indicate, how many generations ago you had ancestors fom the minor populations.

For instance, in my case, I have 82 cM and 47 cM segments from a population that comprises 27% of my ancestry, and 47 cM and 46 cM segments from another (18% of ancestry). Most of the largest segments (up to 87 cM in length) are from the largest ancestral population (39%).

Can I postulate that I should have had ancestors from the minor populations about 3-4 generations ago?