Today, the people behind the Neanderthal genome project (Svante Pääbo's group at the Max Planck Institute) loosed yet another Neanderthal genome on the world, a genome that many press outlets are calling "complete." This one comes from a single toe bone found in the same cave as the finger bone that helped us identify the Denisovans, an extinct group of humans who inhabited Asia tens of thousands of years ago. Apparently, something about the cave environment has preserved ancient DNA extremely well.

That good preservation, combined with improved techniques, has provided a very high quality new sequence. Genome sequences are obtained randomly, typically in stretches about a hundred bases long. Over something the size of a human genome (about 3 billion bases), this randomness means that some areas will be sequenced many, many times, and others will be missed entirely or contain errors that repeated sequencing would allow us to catch. The typical measure of quality for a genome is called "coverage," and that's simply the number of times the average base would be sequenced if every base was covered equally.

In this case, the genome has 50-fold coverage. That's well above draft quality (which tends to be around 30-fold), but there will definitely still be gaps, errors, and places in the genome that aren't sequenced at all. Still, that's about as good as we're likely to get with ancient genomes; the sequence includes almost all of the non-repetitive DNA found in the human genome, and it will provide a valuable resource for comparative studies.

The new genome, labelled Altai (after the region in Siberia where the Densiova cave is) in the diagram above, clearly groups outside the Denisovan and modern human lineages and in with other Neanderthals. But it's somewhat distant from the other Neanderthal genomic sequences we have, which are derived from bones found in Germany and Croatia. According to anthropologist John Hawks, there is also a Y chromosome present, which could allow some additional comparisons with modern humans.

As with the past sequences, the data has been placed in a public archive. Other scientists are free to analyze it, but they should coordinate any publications that analysis produces so that the people who generated the sequence get to have the first say on it.