Lactase persistence in review

Nature this week has a nice news article about the evolution of lactase persistence by Andrew Curry: “Archaeology: The milk revolution”. The article discusses the “LeCHE” project, a multi-million dollar grant that has involved ancient DNA, chemical trace residue analysis, and population genetic modeling work.

The LeCHE project may offer a model for how archaeological questions can be answered using a variety of disciplines and tools. They have got a lot of different tentacles archaeology, palaeoanthropology, ancient DNA and modern DNA, chemical analysis all focused on one single question, says Ian Barnes, a palaeogeneticist at Royal Holloway, University of London, who is not involved in the project. There are lots of other dietary changes which could be studied in this way.
The approach could, for example, help to tease apart the origins of amylase, an enzyme that helps to break down starch. Researchers have suggested that the development of the enzyme may have followed or made possible the increasing appetite for grain that accompanied the growth of agriculture. Scientists also want to trace the evolution of alcohol dehydrogenase, which is crucial to the breakdown of alcohol and could reveal the origins of humanity's thirst for drink.

I think it was a good use of money, getting a broad interdisciplinary group of people to focus on a well-understood evolutionary problem. It would be nice to see more exploratory work, and in particular the one-gene-one-trait model is not going to be nearly so productive for other questions of evolutionary interest to the Neolithic.

This article would be great for students in courses this fall. It is very Eurocentric, though – the story of lactase persistence is much broader than the single European case, although that case has a greater archaeological record, and obviously more funding. When we can add similar detail to the story of trait evolution in Africa – where lactase emerged in three different events instead of one – we’ll really be making progress.