Million-year-old host microbes found in ancient mammoth remains

Mammoth Tooth (Image: Stockholm University/ Love Dalén)

What secrets can a mammoth tooth still reveal? Scientists now say it may carry traces of ancient microbes, preserved for more than a million years.

What did researchers discover in mammoth remains?
An international team at the Centre for Palaeogenetics studied microbial DNA hidden within woolly and steppe mammoth remains. They examined 483 specimens, with 440 sequenced for the first time. Among them was a steppe mammoth that lived around 1.1 million years ago. Their analysis revealed some of the oldest microbial DNA ever recovered, including bacteria that may have caused disease in mammoths.

Which microbes were identified in the study?
Six microbial groups appeared repeatedly across time and regions. These included relatives of Actinobacillus, Pasteurella, Streptococcus, and Erysipelothrix. Some may have been harmful. One Pasteurella-related bacterium resembled a pathogen known to cause deadly outbreaks in African elephants. Given that elephants are mammoths’ closest living relatives, this raises questions about whether similar infections once threatened mammoths.

Mammoth Foot (Image: Stockholm University/Love Dalén)

The team reconstructed partial genomes of Erysipelothrix from a 1.1-million-year-old steppe mammoth. This represents the oldest known host-associated microbial DNA discovered to date.  Scientists indicate it presents a unique opportunity to investigate how microbes influenced disease, adaptation, and extinction in ancient communities.

Why is this important to science today?

While it is hard to quantify the specific influence of these microbes on mammoth health, the results give a glimpse into the biology of extinct populations. Certain microbial lineages have existed with mammoths for hundreds of thousands of years, surviving until the woolly mammoths went extinct on Wrangel Island approximately 4,000 years ago.

Scientists think that the research presents a new window into the past. In addition to sequencing mammoth genomes, researchers can now start to reveal the microbial communities that had inhabited them and shed light on survival and disease in the Ice Age world.