For this month’s ‘Science Notes’, CA’s Deputy Editor Kathryn Krakowka visited the ancient DNA (aDNA) lab at the Natural History Museum in London, to talk to Professor Ian Barnes and Dr Selina Brace about the history of aDNA research, the functions of the lab at the NHM, and what projects they are currently working on.
While the present lab has only existed for six years, the museum has a long history of using molecular biology to explore the human past. Research using blood types to compare populations was carried out in the 1980s, and during the 1990s, with the advent of DNA sequencing, museum scientists tested the possibility of recovering DNA from organisms trapped in amber (Jurassic Park style). These were early days, though, and the hurdles and complexities of working with aDNA meant that eventually the volume of work at the lab petered out.
By 2013, however, with the start of the aDNA ‘revolution’ and next-generation sequencing (see CA 388), interest in this area was renewed. The NHM’s Professors Adrian Lister and Chris Stringer lobbied to start the current lab, soon bringing Ian and Selina in to join the team. Next-generation sequencing made the process hugely more efficient – in the time it had previously taken to sequence a couple of hundred base pairs of DNA, it was now possible to sequence an entire genome. It also made the entire process more accurate, particularly when it came to analysing ancient humans: before, it was almost impossible to distinguish between the DNA of the sample and that of any modern contaminants.
This revolution was led by a few larger, high-profile labs in Germany, Denmark, and the United States – by comparison, aDNA labs in the UK have tended to be smaller, more specialised, and university-based. The NHM’s facility, though, with two full-time staff members and a handful of post-docs and PhD students, is now one of the largest in the country, a fact that highlights both how far the discipline has come and – given that other archaeological laboratories employ dozens of individuals – how much bigger it is likely to grow. This is, unquestionably, an evolving and expanding field.
After discussing the history, Ian and Selina took me to visit the lab itself. While next-generation sequencing has been an immense help in avoiding modern contamination, this can still be a problem, so we viewed the facility through a window. NHM researchers who enter this space first need to go into a prep room, where they don a white jumpsuit, booties, gloves, a mask, and a hood. In addition, after each use, as well as at the end of every day, everything in the lab is cleaned with bleach or sterilised in an oven and/or with UV light.
While watching the researchers at work, Ian and Selina talked me through how a sample is chosen, the steps involved in extracting DNA from that sample, and how the DNA is then sequenced – a process that I will cover in a future ‘Science Notes’. They also brought me up to speed with the research that they are currently working on. The researchers at the NHM have a great resource at their fingertips – the more than 80 million specimens curated there. As Ian described it, when they first began at the NHM they were like ‘kids in a toy shop’, hoping to answer all sorts of questions about specialisation, adaptation, and migration.
In terms of archaeology, one of their biggest projects is exploring the populations of Britain from the Palaeolithic to the present, particularly in terms of how they may have adapted to changing diets and infectious disease. Another piece of research is assessing how prey species were affected by environmental changes during the last Ice Age, and what this may have meant for the humans who hunted them.
The lab also examines animal populations. One of the most interesting projects that Selina is working on at the moment is the evolution of giant ground sloths using well-preserved remains from Mylodon Cave in Chile. More recent phenomena are also of interest to the team: Ian is currently sequencing the genomes of bumblebees in an attempt to assess how changes in land-use practices are affecting their population – a very relevant problem today, as the species is threatened with possible extinction.
With an eye to the future of aDNA research, Ian said, ‘Our remit is to add value to the collections, and I expect over the coming decade we will continue to do this, by expanding the range of organisms we study, and by getting more and more information from each specimen.’