Fossil bone study uncovers unknown animal species and Māori behaviours

Researchers excavating an early Maori midden in Awamoa, just south of Oamaru. Fragments from this site formed part of this study. Photo / Shar Briden

A new study using DNA from fossil bone fragments has provided insights into New Zealand's history that until now have been hidden.

The study, Subsistence practices, past biodiversity, and anthropogenic impacts revealed by New Zealand-wide ancient DNA survey, was led by researchers from Curtin University in Perth, with assistance from University of Otago, Canterbury Museum and Te Papa.

It characterised DNA preserved in fragmented unidentifiable bone from across New Zealand.

By comparing bones excavated from caves that predate human arrival with bones from ancient human kitchen waste (or middens), the researchers characterised the biodiversity that has been lost in NZ.

Curtin PhD candidate Frederik Seersholm said he was most surprised by the sheer number of different species able to be identified through the study.

"We found DNA from over a 100 different species and of these, 14 are extinct today," he said.

"Our results demonstrate that certain species tend to be missed by traditional morphological methods. For example, we identify species of eel and whales in Māori middens which are rarely identified using traditional midden analysis."

Professor Richard Walter from the University of Otago believes the new methods provide much more than an insight into diet.

"They allow archaeologists to model patterns of early Māori mobility, seasonal behaviour patterns, and resource management strategies," he said.

The study found DNA from more than a 100 different species. Of these, 14 are extinct today. Photo / Shar Briden

Professor Michael Bunce, from Curtin University, said the researchers sequenced genetic signatures to identify different species and to characterise different genetic lineages within one species.

"For the ground-dwelling parrot, the kākāpō, surprisingly high amounts of genetic diversity was detected in the bone fragments," Bunce said.

"Of the 10 kākāpō lineages we identified, only one is still around today and this is an indication of the amount of biodiversity lost from one of New Zealand's iconic flightless birds."

The data uncovered in the study highlights the considerable impact humans have had on New Zealand's biodiversity since settling here about 750 years ago.

Dr Nic Rawlence of Otago University's Department of Zoology said that contrary to previous studies the study has shown that Polynesians including Māori had a significant detrimental impact on the genetic diversity of kākāpō.

"The genetic signatures of dolphins and small whales in the same sites, along with putative bone harpoon hooks, suggests Polynesians/Māori may have hunted these species, while the presence of large whales no doubt reflects scavenging of beached carcasses."

Rawlence said the technique will become an important tool in future studies reconstructing early NZ. Researchers also aim to expand the study to other parts of the world.

Seersholm said there is without doubt a great deal of information to be retrieved from fragmented bones.

"It is likely that important future discoveries on extinct species and past biodiversity are hidden in neglected excavation bags in the basements of museums and universities around the globe," he said.

Traditionally, research on the biodiversity of the past has revolved around well-preserved bone fossils, which are used to characterise extinct species.

However, only very few bones from excavations are whole, and many are so damaged they are of no use to researchers. This means a very large proportion of the pieces in the jigsaw puzzle has been left unused.

The study is due to be published this week in the Proceedings of the National Academy of Sciences.