Shells, bones and fishhooks tell a story of sea level change

ARC-supported researchers from The Australian National University (ANU) have led the excavation of a cave – called Makpan – on the Indonesian island of Alor, making an exciting discovery. Shells, fish bones and fishhooks found in the cave show how people once lived and were rapidly adapting to climate change as they made their way towards Australia tens of thousands of years ago.

Makpan witnessed a series of massive sea level highs and lows during its 43,000 years of human occupation, largely due to the climactic extremes of the last Ice Age. According to Dr Shimona Kealy from ANU, analysis of artefacts found at Makpan show how inventive and adaptive its early residents were.

‘When people first arrived at Makpan, they came in low numbers,’ Dr Kealy says. ‘At this time, the cave was close to the coast – as it is today – and this early community lived on a diet of shellfish, barnacles and sea urchin, with sea urchins in particular eaten in large numbers.’

Shortly after their initial arrival, sea levels began to fall. This increased the distance from the site of Makpan to the coast, and likely encouraged people to broaden their diet to include a variety of land-based fruits and vegetables. As the last Ice Age began to wane about 14,000 years ago, Makpan was once again within 1 km of the coast.

The team, led by ARC Australian Laureate Fellow, Professor Sue O’Connor, used radiocarbon dating of preserved charcoal and marine shells to establish the times when people were occupying the cave.

The findings show that Alor was occupied around the same time as Flores to the west, and Timor to the east – confirming Alor’s position as a ‘stepping-stone’ between these two larger islands.

The study was supported by the ARC Centre of Excellence for Australian Biodiversity and Heritage (CABAH), which is administered by The University of Wollongong.

	‘it is no surprise the site sees significant evidence for fishing… not just the bones of a wide variety of fish and shark species, but also in the form of shell fishhooks in different shapes and sizes,’ says ARC Australian Laureate Fellow, Professor Sue O'Connor.