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Science Frontiers ONLINE No. 17: Fall 1981 |
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Why conserve junk?
A. Jeffries, working at Leicester University with globin genes from man and related primates, has been studying how these genes direct the blood cells to make the alpha and beta chains of hemoglobin. Jeffries' analyses seem to indicate that the genes now coding for these hemoglobin chains are almost identical to those existing in human ancestors some 500 million years ago.
Two curious facts have cropped up, however. First, about 200 million years ago, these genes were modified very slightly and relocated to entirely different chromosomes. Second, 95% of the DNA associated with these genes is "junk" -- with no known use. Why did nature conserve junk for 500 million years? Are vital genes in the habit of jumping from one chromosome to another?
(Yanchinski, Stephanie; "DNA: Ignorant, Selfish and Junk," New Scientist, 91:154, 1981.)