“the brother of Japheth the elder.” The KJV and a few other versions read as if Japheth was the oldest, and he was. (See commentary on Gen. 5:32). Most modern versions translate this as if Shem was the older brother of Japheth, but that is not correct and creates a contradiction in the Bible. Although given the construction of the sentence in the Hebrew text Shem would ordinarily be the eldest, the fact that the Bible gives us clear information that Japheth is the oldest shows that the older versions such as the KJV and Darby’s Bible, which have Japheth as “the elder,” are correct.
The flood came when Noah was 600 (Gen. 7:11-12). Noah was said to have children when he was 500 years old (Gen. 5:32), but he did not have all of them that year, only the oldest, Japheth. Since Genesis 11:10 states that Shem was 100 years old two years after the flood, Shem could not have been born when Noah was 500, because then Shem would have been 102, not 100, two years after the flood. It was Japheth that was born when Noah was 500, then, the year of the Flood, Noah’s son Japheth was 100 and Shem was 98, and so Shem was 100 two years after the Flood. Martin Anstey writes: “We arrive at the age of Noah at the birth of Shem by means of an induction from the facts contained in Genesis 7:6 and Genesis 11:10. From Genesis 7:6 we learn that Noah was 600 years at the epoch of the Flood. From Genesis 11:10 we learn that Shem was 100 years old two years after the Flood. Therefore Shem was 98 years old at the Flood, that is, Shem was 98 years old when Noah was 600. Therefore Shem was born when Noah was 502” (Chronology of the Old Testament, Kregel Publications, Grand Rapids, MI, 1973; originally titled “The Romance of Bible Chronology,” 1913. P. 36)