BINANGONAN, Philippines - On a small rock wall a short drive from Manila, enigmatic carvings that are believed to date back 5,000 years are in danger of disappearing before their mysteries can be solved.
The 127 engravings of people, animals and geometric shapes are the Philippines' oldest known artworks, but encroaching urbanization, vandals and the ravages of nature are growing threats.
"Eventually they will disappear … preservation is out of the question," veteran anthropologist Jesus Peralta, who did an extensive and widely respected study of the carvings in the 1970s, told Agence France-Presse.
The artworks have been declared a national treasure, regarded as the best proof that relatively sophisticated societies existed in the Philippines in the Stone Age.
"They show that in ancient times, the Philippines did have a complex culture. It's a recording of our ancestors," said Leo Batoon, a senior researcher of the National Museum.
Museum scientists believe the carvings date back to 3000 BC, based on carving tools and pottery shards discovered at the site, indicating they originated before the use of metal tools.
This makes them far older than the country's second oldest known artworks, a series of geometric shapes in the mountainous northern Philippines that are believed to date to 1500 BC, according to Batoon.
But museum workers say it is difficult to conclusively determine the age of the carvings-scientifically referred to as "petroglyphs"-due to technical and financial constraints.
"Most of our artifacts in the museum are sent abroad and only if we have partners and proponents to spend for such dating," Batoon said.
Little else is known about the figures, or the people who etched them.
One clue is that many of the human carvings appear to be in a squatting position, which has led scientists to theorize that the area was a place of worship.
The carvings were first documented by acclaimed Philippine artist Carlos Francisco in 1965 while he was leading a Boy Scout troop on a hike.
Since then, they have been known as "the Angono Petroglyphs," after Francisco's hometown nearby.