DNA from dirt: Tracing ancient humans found in 'empty' caves The undated photo provided by the Max Planck Institute for Evolutionary Anthropology shows Becky Miller sampling sediment for genetic analyses at the archaeological site of Trou Al'Wesse, Belgium. (Monika V. Knul/Johannes Krause, Max Planck Institute for Evolutionary Anthropology via AP)
DNA from dirt: Tracing ancient humans found in 'empty' caves
Lexile

No bones? No problem!
 
Scientists say they've figured out a way to extract tiny traces of ancient human DNA from dirt in caves that lack skeletal remains.
 
The technique could be valuable for reconstructing human evolutionary history. This is according to the study published in the journal Science.
 
That's because fossilized bones, currently the main source of ancient DNA, are scarce even at sites where circumstantial evidence points to a prehistoric human presence.
 
"There are many caves where stone tools are found but no bones," said Matthias Meyer. He is a geneticist at the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany. He co-authored the study.
 
The researchers collected 85 sediment samples. They took them from seven caves in Europe and Russia that humans are known to have entered or even lived in between 14,000 and 550,000 years ago.
 
By refining a method previously used to find plant and animal DNA, they were able to search specifically for genetic material belonging to ancient humans and other mammals.
 
Scientists focused on mitochondrial DNA. This is passed down the maternal line, because it is particularly suited to telling apart closely related species. And by analyzing damaged molecules, they were able to separate ancient genetic material from any contamination left behind by modern visitors.
 
The researchers found evidence of 12 mammal families including extinct species such as woolly mammoth, woolly rhinoceros, cave bear and cave hyena.
 
By further enriching the samples for human-like DNA, however, the scientists were able to detect genetic traces of Denisovans - a mysterious lineage of ancient humans first discovered in a cave in Siberia - and Neanderthals from samples taken at four sites.
 
Crucially, one of the sites where they discovered Neanderthal DNA was a cave in Belgium, known as Trou Al'Wesse, where no human bones had ever been found, though stone artifacts and animal bones with cut marks strongly suggested people had visited it.
 
Eske Willerslev, who helped pioneer the search for DNA in sediment but wasn't involved in the latest research, said the new study was an interesting step, but cautioned that it's difficult to determine how old sediment samples found in caves are.
 
"In general (it) is very disturbed and unless you can show that's not the case you have no idea of the date of the findings," said Willerslev, an evolutionary geneticist at the University of Copenhagen, Denmark.
 
Meyer said the new method greatly increases the number of sites where archaeologists will be able to find genetic evidence to help fill gaps in the history of human evolution and migration, such as how widespread Neanderthal populations were and which stone tools they were able to make.
 
Scientists may also be able to greatly expand their limited knowledge of the Denisovans, whose DNA can still be found in Melanesians and Aboriginal Australians today, by using the new procedure.
 
"In principle, every cave where there's evidence of human activity now offers this possibility," Meyer told The Associated Press.

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CRITICAL THINKING QUESTION
Why aren’t bones found everywhere?
Write your answers in the comments section below


COMMENTS (5)
  • parkerz-cel
    5/10/2017 - 08:46 a.m.

    Bones arent found everywhere for multiple reasons, one being that people have yet to discover the position in which the bones are found. Another reason is because people and animals dont die everywhere, they tend to die in their habitat or near home, and if the area isnt one of those then there is no reason for bones to be found there.

  • monicas-ste
    5/10/2017 - 11:37 a.m.

    This is really cool. That's crazy that humans have been around longer than we thought. Now more evidence can be found with that advanced technology.

  • jahir-orv
    5/12/2017 - 02:26 p.m.

    because Over Time the Earth has changed in so many ways. The Tectonic plate have moved a lot since.

  • kaileew-ste
    5/18/2017 - 02:13 p.m.

    In ancient caves, if there weren't bones, there wasn't a way to find out who was there. Now apparently scientists have figured out how to scrape DNA from these caves. It is amazing how advanced science is becoming.

  • emilyb2-bur
    5/23/2017 - 07:46 p.m.

    Bones aren't found everywhere because the bones probably dissolve or something and also people don't look all around the world for bones like there could be bones under your house.The earth changes over time and the bones get deeper in the soil and they become harder to find so many people give up but they probably are still there.In my opinion the bones aren't gonna be everywhere you are and if they are it's not like your gonna have a shovel and enough water or supplies .

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