If Moses wrote the lists of geneology in the Bible, then one must wonder why these genealogy in the Bible conflict and disagree, and one must wonder why later writers did not defer to the authority of Moses, in that they freely changed genealogical lists in the Bible to suit their own purposes. While today it is common for some to believe that we know who wrote the Bible, in previous times the first five books of the Bible did not have the undisputed authority they do today. Genealogies are a feature of both the Torah and later books, and usually indicate that priests were at work. Geneologies served a political purpose. For example, one could insist that a certain nation was born from the loins of some particularly unsavory character. One could also claim land by insisting that an ancient ancestor watered a camel on the spot, or purchased a cave there thus establishing precedence. It becomes apparent that these genealogies were later additions (as the need for them arose in changing political circumstances) and this is best demonstrated by the fact that later writers composed a genealogy that conflicted with what we would be led to believe were 'the authoritative history of the world' as composed by Moses.
The Bible is full of conflicting and (therefore obviously) erroneous genealogical lists. A famous example are the the genealogies of Joseph in Matthew Chapter 1 verse 1 and Luke Chapter 3 verse 23 which conflict. (It will then be suggested that one is the genealogy of Mary, which might pass for an explanation if it were the genealogy of Mary, instead of the genealogy of Joseph as stated. Furthermore, it was not customary to denote a person's lineage through any but the father's line, and every other genealogy in the Bible is through the line of fathers and sons, since this was a very patriarchal society. This would be a first if it were true, and it would also be quite odd to give ‘the genealogy of Mary' without mentioning Mary and instead giving the genealogy of Joseph, which is what one finds. When one considers all the other conflicting genealogies of the Bible, what are two more in any case?) These genealogies are laborious to read and anyone interested can look these matters up for themselves. Ezra's genealogy of Benjamin's sons conflicts with that in Genesis and he also describes the Levites differently than in Joshua. The genealogy of Gibeon is described twice in different ways.
Biblical genealogies are problematic, often contradicting each other, resulting in conflicting chronologies. For example we might be led to believe that there were only a few generations separating two events in the Bible, or that there were a dozen generations. It will then be suggested that 'the Bible is self correcting' and that the longer genealogy 'corrects' the shorter version. Now keep in mind that all this is found in a book that is 'infallible and inerrant' that was 'God breathed' and written, without error, under the direct influence of 'the Holy Ghost' and one must wonder how all these 'errors' appeared that need such later 'correction'. It might also be suggested that 'the original Bible' was 'infallible and inerrant' and that the error ridden books that we possess today are only the corrupted copies of this speculative 'perfect original'. A particularly notorious version of this argument was given by some conservative Calvinist named A.W. Pink, who insisted that given that this presently non-existent (and thus impossible to verify) version was 'infallible', those who wanted to critique the current error ridden version were the ones who must prove that this non-existent and perfect original was not perfect in its original form. Given that no such book exists, it is obviously ridiculous to insist that those who just work with what we have got are the ones with the problem, and to further insist that we must 'prove' that a sheerly speculative 'original' was perfect is clutching at straws by these apologists to say the least. First Pink, and others of this sort, must prove that such an allegecd 'perfect original copy' ever existed, and for myself, I could not bother myself to take up Pink's 'challenge' by proving that some speculative original was 'not perfect' when Pink cannot 'prove' that such a document ever existed in the first place.
Pink's argument is not the only one used. For example, when it is convenient we will be reminded of how perfectly the scribes copied the manuscripts, which would suggest that the copies we have today are the originals, and so no such 'perfect original' ever existed in the first place, absent all the problematic passages that have resulted in the creation of what we know as 'Christian apologetics' (something that is only required because the Bible is not self evidently from a single source). We know from the oldest manuscripts found that the manuscripts we have today have remained the same, and were perfectly copied. We also know how strict the copying practices are, and we know that a simple proof checking of corrupted manuscripts would result in the disposal of imperfect error ridden copies. To summarize, there was a perfect original, which was corrupted by copyists, but then again much ado is made about how perfectly copied the manuscripts have been (see the oldest extant originals).
We will be told that a divine miracle took place when the manuscripts were translated into the Greek versions so preferred by authors of the church manuscripts (according to the myth, 70 scribes were locked into 70 rooms and all produced the exact same Greek translation). However the genealogies in the Greek translation add up to one hundred years onto the lives of the earliest Biblical characters, resulting in an 'age of the world' about 300 years greater than what results from tallying up the genealogies in the Hebrew manuscripts.
Even within the Hebrew manuscripts there all kinds of curiously conflicting genealogies. The simple explanation is that the Bible consists of diverse source materials, and the conflicts only become apparent when such divergent traditions are gathered together into the composite work we know of as the Bible.
As just one example you can compare the genealogy in 1st Chronicles with the genealogy in the book of Ezra.
"The children of Amram: Aaron, Moses, and Miriam. The sons of Aaron: Nadab, Abihu, Eleazar, and Ithamar. Eleazar was the father of Phinehas, Phinehas of Abishua, Abishua of Bukki, Bukki of Uzzi, Uzzi of Zerahiah, Zerahiah of Meraioth, Meraioth of Amariah, Amariah of Ahitub, Ahitub of Zadok, Zadok of Ahimaaz, Ahimaaz of Azariah, Azariah of Johanan, and Johanan of Azariah (it was he who served as priest in the house that Solomon built in Jerusalem). Azariah was the father of Amariah, Amariah of Ahitub, Ahitub of Zadok, Zadok of Shallum, Shallum of Hilkiah, Hilkiah of Azariah, Azariah of Seraiah, Seraiah of Jehozadak..." (1 Chronicles 6:3)
The book of Ezra comes from an extremely conservative tradition that wished to reinstate the strictest interpretation of the Torah, and the strictest separation of the Jewish nation from surrounding cultures, and as a part of this polemic wishes to link a character named Ezra with Aaron, the original Levite priest. (See the page on dating the time of the Torah composition for my discussion of the book of Ezra.) Note that the following genealogy of Ezra begins with Ezra and works backwards to Aaron, the High Priest.
"Now after this, in the reign of Artaxerxes king of Persia, Ezra the son of Seraiah, son of Azariah, son of Hilkiah, son of Shallum, son of Zadok, son of Ahitub, son of Amariah, son of Azariah, son of Meraioth, son of Zerahiah, son of Uzzi, son of Bukki, son of Abishua, son of Phinehas, son of Eleazar, son of Aaron the chief priest..." (Ezra 7:1)
Note that the Chronicles list does not include Azariah and that the father Amariah is said to be the son of Azariah (not Meraioth) in the list given in Ezra. The list in Ezra then omits Ahimaaz, and then Azariah appears in the Chronicles list as the son of this Ahimaaz. Chronicles then goes on to list Johaan, another Azariah, another Ahitub, then comes into agreement again with Ezra mentioning Zadok and Shallum, Hilkiah, Azariah, and Seraiah (which must have meant that Ezra was the brother of Seraiah and the uncle of Jehozadak). It is also interesting to note that Ezra was not considered important enough to be included in the Chronicles genealogical listings (Ezra was written much later than the time it purports to describe, and was a type of religious polemic. The same polemical revision of the Chronicles genealogy is found in Matthew's genealogy, and the chronological problems are further disucssed and compared to the time line of Matthew's genealogy on this page.)
The obvious question then remains as to which of these genealogies is to be accepted as correct, and thus useful in determining such things as the age of the universe (for those interested in attempting to decipher such things from these ancient manuscripts.) However we are told in verse 15 that Jehozadak was sent into exile by Nebuchadnezzar, and thus it must have been the case that Ezra was another one of those famously old aged Biblical characters, since this book is set in a time several generations later. So there are obvious problems reconciling the two genealogies, and there are chronological problems, and it is also interesting to note that while a whole host of other Biblical characters are incorporated into the Chronicles genealogy, Ezra is not. It is understood that Chronicles was written after the return from the Babylonian exile and so this omission can only be explained if we understand that the Ezra account was written much later than the events that it purports to describe, in otherwords it is polemical and addresses itself to a certain social situation that was contemporary with the composition using the common biblical technique of employing mythological polemic referring back to a certain historical time (and thus attempting to establish a certain social situation based on the argument of precedent).
In biblical manuscripts we are told that Hebrew nation was in slavery in Egypt for 400 (or 430) years. Then again it is suggested in genealogies that they were in Egypt for only a few generations (perhaps 100 or 120 years, depending on how one wishes to define the length of a generation).
The problem becomes apparent in the following genealogical list where the one of the grandsons of Levi is the father of Moses and Aaron (you can also note that he married his father's sister in violation of later Levitical law, but that sort of thing is a separate problem).
"These are the names of the sons of Levi according to their generations: Gershon, Kohath, and Merari, the years of the life of Levi being a hundred and thirty-seven years. The sons of Gershon: Libni and Shimei, by their families. The sons of Kohath: Amram, Izhar, Hebron, and Uzziel, the years of the life of Kohath being a hundred and thirty-three years. The sons of Merari: Mahli and Mushi. These are the families of the Levites according to their generations. Amram took to wife Jochebed his father's sister and she bore him Aaron and Moses, the years of the life of Amram being one hundred and thirty-seven years." (Exodus 6:16)
There is a similar passage in 1 Chronicles...
"The sons of Levi: Gershom, Kohath, and Merari. The sons of Kohath: Amram, Izhar, Hebron, and Uzziel. The children of Amram: Aaron, Moses, and Miriam. The sons of Aaron: Nadab, Abihu, Eleazar, and Ithamar." (1 Chronicles 6:1)
The book of Numbers also insists that Amram was the grandson of Levi and the he married his father's sister, and was the father of Moses and Aaron.
"The name of Amram's wife was Jochebed the daughter of Levi, who was born to Levi in Egypt; and she bore to Amram Aaron and Moses and Miriam their sister." (Numbers 26:59)
The book of Chronicles repeats a Levite genealogy, and also tells us that Moses was the great grandson of Levi, indicating that traditions of '400 (or 430) years of slavery in Egypt' came from a totally separate source from the sources just referenced above.
"And David organized them in divisions corresponding to the sons of Levi: Gershom, Kohath, and Merari. The sons of Gersham were Ladan and Shimei. The sons of Ladan: Jehiel the chief, and Zetham, and Joel, three. The sons of Shimei: Shelomoth, Haziel, and Haran, three. These were the heads of the fathers' houses of Ladan. And the sons of Shimei: Jahath, Zina, and Jeush, and Beriah. These four were the sons of Shimei. Jahath was the chief, and Zizah the second; but Jeush and Beriah had not many sons, therefore they became a father's house in one reckoning. The sons of Kohath: Amram, Izhar, Hebron, and Uzziel, four. The sons of Amram: Aaron and Moses. Aaron was set apart to consecrate the most holy things, that he and his sons for ever should burn incense before YAHWEH, and minister to him and pronounce blessings in his name for ever." (1 Chronicles 23:6)
Another strange genealogical twist is introduced in the book of Acts, where Abraham is said to have purchased the ancestral burial ground from Hamor, an event that took place long after his death during the days of his grandsons. (For further discussion see the page Where were the religious shrines located?)
"And they were carried back to Shechem and laid in the tomb that Abraham had bought for a sum of silver from the sons of Hamor in Shechem." (Acts 7:16)
These are just a few examples that indicate that the Bible is composed of variant source materials, and which indicate that the attempt to 'calculate the age of the earth' based on genealogies is a waste of time. The Bible is a book composed of variant traditions, religious and political polemic from different competing ideological groupings and not a purely historical document.