I don't know this. I don't think anyone does. The geneologies are compressed. The word often translated "became the father of" often does not mean the immediate father, but as one who "started a line leading too". In some places we have "S became the father of Z" while in another place it is clear that S is the great great-grandfather of Z, for they mention T,U,V and the rest coming inbetween.
Maybe they could be streched from 5K back (as a noncompressed reading would show), to 50K back, but I can't see it going any further. If the first humans really did walk the Earth 200K back, it is a death blow to bibical creationism, IMHO.
Biblical Creationism has already been dealt several death blows. It's quite dead but to the mindless folks who still accept it