Paleogeneticists at the Centre for Paleogenetics in Sweden have made a remarkable new find. They also recovered the world’s oldest known host-associated microbial DNA from ancient mammoth remains. Postdoctoral fellow Benjamin Guinet leads this study. More broadly, it provides a fascinating glimpse at the complex interplay between mammals and their microbial communities during the Pleistocene epoch. These findings indicate that these early microbes could have played a role in mammoth adaptation, disease, and extinction.
The research team, which includes Professor Love Dalén and senior author Tom van der Valk, identified six distinct microbial groups consistently associated with mammoth hosts. These groups include cousins of some very familiar bacteria like Actinobacillus, Pasteurella, Streptococcus and Erysipelothrix. This exceptional find underscores the microbial diversity that existed back then. It further provides important glimpses into how these microorganisms shaped the health, prosperity, and survival of their mammalian hosts.
Discovery of Ancient Microbial DNA
The research centered on the remains of a mature steppe mammoth that lived around 1.1 million years ago. Through rigorous analysis, the team managed to reconstruct partial genomes of Erysipelothrix from these ancient remains, marking a significant milestone in paleogenetics. The greatest challenge proved to be getting high-quality DNA data dating back over a million years, since microbes have an incredibly fast evolutionary rate. The researchers did not stop here, passing this hurdle to recover DNA that offers a glimpse into the past.
This ancient DNA allows for the first time to show that many microbial lineages have coexisted with mammoths for hundreds of thousands of years. In doing so, they simultaneously targeted distinct geographic ranges and evolutionary timescales. These findings reflect an ancient co-evolutionary history between these mammals and their microbial affiliates. Of all the Pasteurella-blaming bacteria isolated from sinus-navels, one in particular made itself the most interesting. This bacterium is only distantly related to a pathogen that has caused lethal epidemics in contemporary African elephants.
Implications for Understanding Mammoth Vulnerabilities
This discovery suggests that mammoths may have been susceptible to specific infections like those that affect their closest living relatives today. Among these cousins are the African and Asian elephants. That underlying vulnerability may have been part of what led them to eventually go extinct. From this, researchers can look at how diseases ravaged ancient creatures throughout the Pleistocene. They do this through research into the microbial environment of these ancient peoples.
The broader impacts of this research go far beyond an interest in mammoths. It provides context for understanding how microbes shape adaptation and disease in large mammals across eras. Studying ancient DNA is expected to become a key method for gaining valuable insight into past ecosystems. This expertise now allows us to know what caused these species to decline.
Future Research Directions
Together, Guinet, Dalén, and van der Valk have done pioneering work. Their work provides a thrilling new door into the field of evolutionary genomics and paleobiology. The ability to recover ancient microbial DNA gives us a great upper hand when reconstructing what mammoths were like. It truly opens up the possibility of future research on other extinct species as well. Researchers will continue to explore how microbial communities may have influenced animal health and survival in diverse ecological contexts.