Leo Speidel, Unit Leader

Please describe your current research.

My work aims to understand the evolutionary forces that have shaped human genetic differences and how these may impact our health. Excitingly, we can now look back many hundreds of millennia into the past by extracting DNA from ancient bones and applying new statistical techniques that reconstruct the genetic trees that relate these people back in time.

Using these techniques, my team can reveal historical events in unprecedented detail by demonstrating how these have impacted the genomes of our ancestors. Our work has identified population bottlenecks and expansions, mixtures and migrations of human groups over millennia and adaptations to dramatic changes in climate, lifestyle and pathogens.

From this, we can show the evolutionary trajectory of mutations that cause disease and can also reveal more about the molecular machinery that introduces this variation through the generations.

Please describe your role.

I’m a unit leader at RIKEN’s Center for Interdisciplinary Theoretical and Mathematical Sciences (iTHEMS). I joined RIKEN in November 2024 as part of the Early Career Leaders program, which supports junior group leaders as they establish a research group. Before this, I was at University College London in the UK and at the biomedically-focussed Francis Crick Institute. There, I was a Sir Henry Wellcome Fellow, which also aims to support recently qualified postdoctoral researchers as they start independent research careers.

What are some interesting recent discoveries in your field?

When I started my PhD, I was fascinated by a 2015 Nature paper that looked at the genetic structure of the people of the UK at very fine scales. It suggested links between this structure and the different historical migrations into the UK, such as the arrival of Anglo–Saxon-related people in the fifth century. It was mind blowing to me to think that such information is still traceable in our DNA. These insights would not be accessible without some recent innovations in the statistical modeling of our DNA differences.

This year, we published a method in Nature that has allowed us to pinpoint migration events in Europe using ancient DNA, revealing significant migration events dating back to the first millennium AD in early medieval Europe that were previously unknown.

Among other things, we’re working on applying this method to different regions around the world, including Japan.

What RIKEN technologies help you to do your work?

We test our methods on simulations and then apply these to large-scale genetic data, where we rely heavily on high-performance computers, such as RIKEN’s Hokusai supercomputer.

What has been your most memorable experience at RIKEN?

I’ve only been at RIKEN for six months, but my most memorable experience so far has been a recent outreach event aimed at high school students. Our center, iTHEMS, is home to a diverse group of multidisciplinary researchers, who all incorporate mathematics and its applications into their work. In addition to interacting with the students, it was great to hear my colleagues talk and to really understand for the first time what some of them work on!