British and Italian scientists have painstakingly spelled out the entire genome of the mitochondria — the tiny powerhouses within each cell — taken from intestinal cells of the remarkably well-preserved iceman. ...What this means is that there are, as far as in known, no living descendents from the maternal side of Oetzi's family, no one from any aunts or sisters. That doesn't, however, rule out the possibility of descendents: If he had sons, they would not have received his mitochondrial DNA - which is, again, passed down only through females - but they would have inherited his Y chromosome.
The new analysis, published in the Nov. 1 issue of Current Biology, shows that his mitochondrial genes don't match up with any retrieved so far from modern-day humans. That virtually rules out any descendants from Oetzi's maternal lineage....
Mitochondrial DNA is passed down only from mothers to their offspring. It's an important tool for constructing family trees and tracing the movement of people across time and space. Mitochondrial DNA has only about 16,500 genetic units, called base-pairs, instead of the 3 billion in the entire human genome. And the mitochondrial genome is peppered with lots of mutations, unique genetic tags that make it easier for scientists to track genetic lineages.
So while Martin Richards of the University of Leeds says that "the maternal lineage of the iceman has apparently gone extinct," he's thinking of sequencing Oetzi's Y chromosome - a far bigger undertaking because it has far more genetic elements than the mitochondria. But Oetzi just may still have some distant relatives around.
Understand that this is "not earth-shattering," in the words of molecular anthropologist Ann Stone of Arizona State University, because "a sample size of one is difficult to do much with." Still, it ultimately might provide some additional clues to life in the copper age.
And besides, as Stone says, it's "kind of cool."
Posts
No comments:
Post a Comment