Scientists claim they have found the oldest evidence of human creativity: a 350,000-year-old pink stone axe.
The handaxe, which was discovered at an archaeological site in northern Spain, may represent the first funeral rite by human beings.
It suggests humans were capable of symbolic thought at a far earlier date than previously thought.
Spanish researchers found the axe among the fossilised bones of 27 ancient humans that were clumped together at the bottom of a 14-metre- (45 feet) deep pit inside a network of limestone caves at Atapuerca, near Burgos.
It is the only man-made implement found in the pit.
It may confirm the team's belief that other humans deposited bodies in the pit deliberately.
Professor Eudald Carbonell, of the Rovira i Virgili University in Tarragona, Spain, and a key member of the team that unearthed the axe, was jubilant about the find.
"It's a great discovery. This is an interpretation, but in my opinion and the opinion of my team, the axe could be the first evidence of ritual behaviour and symbolism in a human species," Professor Carbonell said.
"We conclude it could be from a funeral rite," he added.
HUMAN FAMILY TREE
Scientists are trying to piece together the species relationships
The axe is skilfully crafted from quartzite rock, which is abundant in the region.
Handaxes of this type are usually used for butchering animal carcasses for their meat. But the researchers claim the striking colour is crucial to its importance.
"It's a very special colour," said Juan Luis Arsuaga, director of the Atapuerca excavation. "They would have needed to search it out. I think this colour had some significance for [these humans]," he added.
The human remains belong to the species Homo heidelbergensis, which dominated Europe around 600,000-200,000 years ago and is thought to have given rise to both the Neanderthals and modern humans (Homo sapiens).
But some researchers, such as Peter Andrews, of the Natural History Museum in London, have proposed that the skeletons were lying elsewhere in the caves and sludged into the pit by a mudflow.
"I'm cautious about its significance," said Professor Chris Stringer, also of the Natural History Museum. "The association of the handaxe and the skeletons in this pit of bones is a very interesting one," adding that it was possible there was some sort of symbolic association.
"But one has to put some caution into [this announcement] because it has been suggested that this is a secondary deposit and therefore could be accidental," he noted.
But Arsuaga thinks it unlikely that so many human remains could have appeared in the pit in the absence of bones from other animals.
Previously, the earliest funeral rituals were thought to be associated with Neanderthal remains dated 100,000 years ago. But some researchers dispute the significance of these sites, preferring to believe that abstract thinking began around 50,000 years ago in modern humans.
Arsuaga and his colleagues found the handaxe in 1998, but decided to search for other stone tools in the pit before announcing the find. They have found none so far.
The research is published in the French journal L'Anthropologie.