john hawks weblog

paleoanthropology, genetics and evolution

Sequencing FTL neutrinos

Sat, 2012-03-17 11:13 -- John Hawks

A well-written blog account of a current controversy in human genetics, by Joe Pickrell: "Questioning the evidence for non-canonical RNA editing in humans".

The observation that I personally found most convincing is displayed in the plot at the beginning of this post. What I’m showing is that mismatches to the genome at RDD sites occur almost exclusively at the ends of sequencing reads. All three technical comments include this observation. Importantly, Lin/Piskol et al. take this analysis one step further. They show (in their Figure 2) that this effect is driven by the fact that mismatches to the genome at RDD sites tend to occur at the beginning of sequencing reads that go in the opposite direction of transcription (this effect is masked in my plot).

It's a bad sign when 90% of your observations may result from sequencing errors. That's something we spend a lot of time trying to understand and work around in the archaic human genomes. We frequently find that, while the genetics ought to follow a mathematical model perfectly well, the sequence data are noisy in ways that interfere substantially with our predictions.

It's the same thing as using bad wiring in a neutrino experiment, really. If you know about it, you can work around it. Otherwise, it's liable to mislead you.

Neandertals

For years, I've worked on their bones. Now I'm working on their genes. Read more about the science studying these ancient people.

Denisova

From a finger bone of an ancient human came the record of a completely unexpected population. My lab is working on the science of the Denisova genome.

Acceleration

The advent of agriculture caused natural selection to speed up greatly in humans. We're uncovering some of the ways that populations have rapidly changed during the last 10,000 years.

Malapa

Just outside Johannesburg, the Malapa site is producing some of the most exciting finds in human evolution. This site is the headquarters of the Malapa Soft Tissue Project.