Guatemala — Archaeologists excavating a pyramid complex in the Guatemalan jungle have uncovered the earliest example of Mayan writing, 10 bold hieroglyphs painted on plaster and stone.

The 2,300-year-old glyphs were excavated in April in San Bartolo and suggest the ancient Mayas developed an advanced writing system centuries earlier than previously believed, according to an article published Thursday in the journal Science.

The glyphs date from between 200 B.C. and 300 B.C., and come from the same site in the Peten jungle of northern Guatemala where archaeologist William Saturno found the oldest-known murals of the Mayan world in 2001. Radiocarbon tests prove the writing is 100 years older than the murals, which depict the Mayan creation myth.