Scientists claim to have discovered a "prehistoric version of Facebook" used by Bronze Age tribes to communicate with each other.
Studying thousands of images scrawled across two granite rock sites in Russia and Sweden, a Cambridge University team claimed the sites were like an "archaic version" of the social networks where users shared thoughts and emotions and gave stamps of approval to other contributions - similar to the Facebook "like".
"There's clearly something quite special about these spaces. I think people went there because they knew people had been there before them," study researcher Mark Sapwell said in a statement.
"Like today, people have always wanted to feel connected to each other - this was an expression of identity for these very early societies, before written language," he said.
Scientists believe ancient man continued to go back to the exact same locations to draw and communicate for thousands of years as it provided them with "comfort" and a deep human "connection".
According to Sapwell, the sites they are investigating --one in Zalavruga in Russia and another in Namforsen, Northern Sweden -- contain around 2,500 images such as animals, humans, boats and hunting parties.
Using analytical software, Sapwell's team is comparing the imagery over large areas -- adding and taking off layers to create a sense of how people built on existing images.
Sapwell, a PhD archaeology student at St John's College, said: "Like a Facebook status invites comment, the rock art appears very social and invites addition - the way the variations of image both mirror and reinterpret act as a kind of call and response between different packs of hunters across hundreds - even thousands - of years."
The team also discovered that as the prehistoric art developed, it began to go "mobile". It came off the rock and appeared on tools like the handles of slate knives and pots.
"These sites are on river networks, and boat is likely how these Bronze Age tribes travelled," Sapwell said.
"They are natural spots to stop and leave your mark as you journey through, like a kind of artistic tollbooth," he added.