'Moon landing' of genetic science as bear DNA sequenced from cave dirt

Rob Waugh
·Contributor
·3 min read
The find offered insights into bears from more than 10,000 years (Ronaldino and Grant Zazula, Yukon Beringia Interpretation Centre)
The find offered insights into bears from more than 10,000 years (Ronaldino and Grant Zazula, Yukon Beringia Interpretation Centre)

Stone Age black bears which defecated in a cave in Mexico 16,000 years ago have opened up a new frontier in genetic science, researchers have said. 

Researchers used soil from the cave to sequence ancient DNA from soil for the first time.

The findings have been described as the ‘moon landings’ of genomics because researchers will no longer have to rely on finding and testing fossils to determine genetic ancestry, links and discoveries.

It could rewrite what we know about everything from evolution to climate change. 

Read more: Dogs evolved ‘puppy dog eyes’ just to appeal to humans

A team of scientists led by Cambridge researchers recreated the genomes of animals, plants and bacteria of microscopic fragments of DNA found in Chiquihuite Cave.

This ‘scientific first’ has wider significance as it increases scientists’ ability to study the evolution of animals, plants and microorganisms.

This is because working with highly fragmented DNA from soil samples means scientists no longer have to rely on DNA samples from bone or teeth for enough genetic material to recreate a profile of ancient DNA, which opens up the field to what can be tested and studied.

The samples included faeces and droplets of urine from an ancestor of North America’s most familiar and common bear – the American black bear – which allowed scientists to recreate the entire genetic code of two species of the animal. 

The first is the Stone Age American black bear, the second is an extinct short-faced bear called Arctodus simus which died out 12,000 years ago. 

Professor Willerslev said: “When an animal or a human urinates or defecates, cells from the organism are also excreted. And the DNA fragments from these cells are what we can detect in the soil samples. 

“Using extremely powerful sequencing techniques, we reconstructed genomes – genetic profiles – based on these fragments for the first time. 

Watch: Why we are all attracted to conspiracy theories

Read more: Mysterious “rogue planet” could be even weirder than we thought

“We have shown that hair, urine and faeces all provide genetic material which, in the right conditions, can survive for much longer than 10,000 years.”

“All over the world, everyone scientifically involved in the study of ancient DNA recognised the need to reconstruct genomes from fragments found in soil or sediment. 

"Being able to do that for the first time means we have opened up a new frontier. 

“Analysis of DNA found in soil could have the potential to expand the narrative about everything from the evolution of species to developments in climate change – this is the moon landing of genomics because fossils will no longer be needed.”

Assistant professor Mikkel Winther Pedersen from the University of Copenhagen sampling the cave sediments for DNA (Credit: Devlin A. Gandy)
Assistant professor Mikkel Winther Pedersen from the University of Copenhagen sampling the cave sediments for DNA (Devlin A. Gandy)

The same group of scientists revealed last year that DNA analysis of the plant and animal remains from the sediment packed around the tools in the cave dates the tools and the human occupation of the site to 25,000-30,000 years ago – 15,000 years earlier than people were previously thought to have reached the Americas. 

Watch: Will we ever get a pill to reverse ageing?