Ancient Australians Burned Grass in Rituals for 25,000 Years

Deep inside Cloggs Cave in southeastern Victoria lies evidence of one of humanity’s longest-lasting cultural practices. Archaeologists have uncovered layers of ash stretching back 25,000 years, suggesting that the GunaiKurnai people performed elaborate rituals in this sacred space across more than 1,000 generations.

The discovery, announced in 2024, reveals that Indigenous inhabitants didn’t just visit the cave occasionally. They returned repeatedly, century after century, to conduct ceremonies involving the burning of grasses. Bruno David from Monash University and Russell Mullett, a GunaiKurnai elder, led the research team in piecing together this remarkable story from microscopic plant fossils.

Tiny Clues Tell an Ancient Story

The key to unlocking this history lies in phytoliths, microscopic structures that plants create when they absorb silica from soil. When grasses are burned, these phytoliths survive as ash, preserving evidence of the plants for thousands of years. The researchers found thousands of these preserved cells inside the cave, with grasses making up 97 percent of the burnt phytoliths discovered.

“People brought whole grasses, including their roots, into the cave and burnt them to repeatedly make thin layers of ash,” David explains. This wasn’t random activity. The precision and repetition suggest deeply intentional, ceremonial behavior.

What makes this finding particularly powerful is how it connects ancient practice with recorded history. In the 1880s, anthropologist Alfred Howitt documented ceremonies performed by GunaiKurnai medicine men and women, describing them as “wizards.” His accounts specifically mentioned ash as a crucial component of their rituals. Now, archaeologists have traced this same practice back 25,000 years.

A Practice Intensifies Over Time

The ash layers weren’t deposited uniformly across the cave’s history. Between 4,400 and 1,600 years ago, the burning became more frequent and widespread across the cave floor. Around 2,000 years ago, a standing stone was erected in the cave, and for the next 400 years, grass was burnt around it in concentrated patterns.

This shift from sporadic burning to dense, repeated ashy layers tells us something important: the rituals became more formalized and central to life at the site. Earlier periods show evidence of other ritual activities, like fires with fat-smeared sticks and ceremonies involving stalactites. But the grass-burning practice clearly intensified and dominated later periods.

Why Grasses Matter

The choice of grasses wasn’t accidental. “Grasses immediately turn to ash rather than charcoal when burnt, and the ash was considered important for ceremonies,” David notes. This distinction reveals something about GunaiKurnai knowledge and preferences. They understood the properties of different plants and selected grasses specifically for how they transformed during burning.

Ruling out alternative explanations required careful scientific work. Unlike pollen, which travels on wind, phytoliths typically land right beside their source plants. The researchers confirmed the fossils weren’t washed in by floods. They even distinguished between burnt phytoliths from human activity and unburnt ones deposited in possum droppings found in the cave.

A Gap in Understanding

According to Anna Florin at the Australian National University, archaeobotanical research has been underrepresented in Australian archaeology, meaning “a large portion of past life has been understudied.” This Cloggs Cave research represents the kind of interdisciplinary work that can change that. By combining careful scientific analysis with GunaiKurnai cultural knowledge, researchers revealed a practice spanning more than 25 millennia.

The cave tells us that human cultural practices can prove remarkably persistent. A ritual performed 25,000 years ago, modified and refined over thousands of years, was still being practiced when Europeans arrived in Australia. That kind of cultural continuity challenges our assumptions about how societies change and evolve over deep time.

What other ancient practices, now forgotten, might be hiding in archaeological sites waiting for researchers to decode their hidden meanings?

Source: New Scientist