Joe Carter has a very thought provoking post (Debatable: Genesis, Genealogies, and the Age of the Earth), and some very intelligent comments on the claim that the genealogies in the bible should not be used for trying to determine the age of the earth because is it common to leave people out.  This does not mean that the YECs are incorrect in assuming a young earth, but the calculations of 6000 years may be inaccurate because the genealogies skip generations.  Or, as Joe summarized:

These points cast considerable doubt on the supposition that the genealogies in Genesis 5 and 11 were ever intended to be a direct chronology, much less one from which the age of the earth could be deduced. Based on this evidence alone, there is no reason to assume that our planet has only been around for 6,000 years.

Here are some selected passages from the post and the comments which I found thought provoking:

There are obvious and intentional abbreviations and conventions which indicate Biblical genealogies are not understood to be comprehensive historiography, but to ground certain historical/social/political claims.

Yep.  Like in the NT, Matthew is trying to prove that Jesus is the seed of David, so he traces the genealogy back to David.  I’m sure that his choices of intervening generations was probably just as important and instructional.

On example we see is in Christ’s genealogy in Matthew, where we read:

Asa was the father of Jehoshaphat, Jehoshaphat the father of Joram, and Joram the father of Uzziah. (Matt. 1:8)

which one can compare to

11 Joram his son, Ahaziah his son, Joash his son, 12 Amaziah his son, Azariah his son, Jotham his son, (1 Chron 3:11-12)

In this geneology (Azariah is the same person as Uzziah) we see that there are three generations missing from Matthew’s account, which makes Uzziah appear to be Joram’s son rather than his great-grandson. That is all fine and dandy considering Matthew’s purpose was to explain Christ’s Davidic (legal) bloodline. Nevertheless it calls into question the precision of Matthew’s concluding:

So all the generations from Abraham to David are fourteen generations; from David to the (10) deportation to Babylon, fourteen generations; and from the (11) deportation to Babylon to the Messiah, fourteen generations. (Matt. 1:17)

I don’t know a resolution to this issue, although I don’t dwell on it very much. (If I were intent on disproving biblical inerrancy, I would bring this up much faster that stating that the bible teaches pi = 3)

A very interesting dilemma indeed.  I wonder what the apology for that is???

None of the other places in Scripture that replicate the Genesis genealogies (1 Chronicles 21, Luke 3) indicates an abbreviated genealogy in Genesis (except the 2nd Cainan, which is a red herring).  It is then dangerous to assume that the Genesis genealogies are abbreviated (which is essentially what W. H. Green does), because we have no basis for doing so.

The genealogies of Genesis are unique among Biblical genealogies. First, they alone include specific ages. Second, though the primary purpose of these ages may not be to calculate chronology, the calculation of chronology on the basis of them is certainly a legitimate use of them. Third, the Genesis genealogies alone use the Hifil of yalad for “begot.” All others use the Qal. The Hifil seems to be used intentionally to indicate immediate son, rather than remote descendant.

Ahhh, so.