London: A 40,000-year-old bracelet found in Siberia has set researchers believing that ancient humans used drills which were just like modern tools.
The "unique" green stone bracelet believed to be the oldest ever found as it dates back around 40,000 years was discovered inside the Denisova Cave beside ancient human remains.
Scientists said there is evidence that the bracelet's maker used a 'drill'.
The intricate modern-looking piece of polished jewellery, "perhaps belonging to a princess", was made of chlorite by the Denisovans.
Experts who have spent years examining the bracelet since its discovery in 2008 said that it was an exceptionally rare item of the era and likely held great significance for the wearer, reported Daily Mail.
In addition, the level of skill and expertise required to create the piece has led to speculation that these earliest humans were more technologically advanced than previously thought, with the Denisovans seemingly more skilled than Homo sapiens or Neanderthals.
Scientists found that a hole had been drilled in part of the bracelet with such precision that it could only have been done with a high-rotation drill similar to those used today.
It was also carefully polished, with a heavy pendant added in the centre, probably hanging from a short leather strap.
The archaeologists have ruled out that the bracelet was made in a later era and buried with the earlier Denisovan remains.
Scientists also noted it was made of chlorite, a stone found more than 250 km away, suggesting the bracelet was of significance at the time.
This unique jewellery is currently held at the Museum of History and Culture of the Peoples' of Siberia and the Far East in the city of Novosibirsk.