Study Estimates 2.22 Million Indigenous Australians Lived Before Colonisation, With 93% Lost by 1861

A much larger population before 1788

An estimated 2.22 million Indigenous people lived in Australia before the First Fleet arrived in 1788, according to research published on 15 September 2026 in Nature Human Behaviour. The study calculates about 2.06 million excess deaths between 1788 and 1861, placing the population collapse following British colonisation on a far greater scale than many earlier estimates suggested.

The researchers combined archaeological evidence, genetic reconstructions and models of how many people Australian environments could support. Their central estimate falls within a likely population range of roughly 1 million to 4 million. The breadth of that range reflects the difficulty of reconstructing a population whose communities suffered disease, displacement and violence before comprehensive counting began.

The Nature Human Behaviour study describes a decline of about 93% within less than 80 years of the First Fleet's arrival. Its estimate of 28,200 excess deaths a year over 73 years covers deaths associated with introduced diseases, frontier violence and the disruption of Indigenous ways of life.

The findings also require care when comparing past and present. The researchers use the 2021 Census count to put the Indigenous population at about 37% of their estimate for 1788. The Australian Bureau of Statistics' adjusted resident population estimate for the same year was higher, at 983,709, equivalent to about 44% of 2.22 million.

Lead author Associate Professor Alan Williams, a researcher at James Cook University and a partner investigator representing EMM Consulting in the Centre of Excellence for Indigenous and Environmental Histories and Futures, described both the loss and the survival documented by the research:

These devastating findings highlight the major impacts of invasion experienced by Indigenous Australians, and demonstrate their remarkable survival, resilience and recovery over the past century.

Why earlier population estimates were so low

Anthropologist Alfred Radcliffe-Brown's calculations from around 1930 shaped estimates of Australia's Indigenous population for decades. The research team's institutional announcement cites his figure as 250,000; an explanation published by the authors through UNSW gives 300,000. Previous estimates more broadly ranged from 250,000 to 1 million.

The new median of 2.22 million is more than twice the upper end of that range. Compared with 300,000, it is about 7.4 times as large; compared with 250,000, it is about 8.9 times as large. These comparisons explain why the size of the revision depends on which historical figure is used.

Colonial records often counted people at blanket distributions, ration depots, missions, reserves and pastoral stations. Many people were outside those settings, while administrative practices excluded many people of mixed ancestry. Observers were also recording communities after deaths and displacement had already reduced their numbers.

The authors' UNSW research explanation says no comprehensive census of Indigenous Australians existed until 1971. Their approach therefore looks beyond colonial headcounts to evidence that can reach further into the past.

How researchers reconstructed the population

More than 5,000 archaeological radiocarbon dates formed one strand of the research. Radiocarbon dating estimates the age of organic material. Taken together, dates from archaeological sites can help researchers reconstruct changes in human activity and population through time.

Genetic evidence provided another strand. Researchers used genetic patterns to infer past effective population size, a technical measure related to the people contributing genetic variation across generations. Turning those patterns into estimates of a whole population requires assumptions and modelling.

Environmental modelling supplied a third approach. The researchers estimated carrying capacity, meaning how many people local environments could support, using environmental productivity and assumptions about communities living without agriculture.

The journal paper identifies agreement between the modelled and genetic estimates as the basis for its median of 2.22 million. Historical and ethnographic estimates did not align with those results. Archaeology contributed to the wider reconstruction, rather than every type of evidence receiving equal weight in the final calculation.

The median was calculated through bootstrapping, a statistical method that repeatedly samples estimates to examine their combined distribution. The resulting density, 0.29 people per square kilometre, is an average across the continent. Communities would have lived at different densities according to local conditions and resources.

The team has made analyses and R code available through two Zenodo records, identified as 10.5281/zenodo.13451032 and 10.5281/zenodo.20083870. Those records allow other researchers to examine how the calculations were made.

What the death estimate means

The researchers used a demographic model that accounted for population age to connect their estimate for 1788 with early census information. Their central calculation produced approximately 2.06 million excess deaths, averaging about 28,200 annually between 1788 and 1861.

Excess deaths are deaths beyond the number expected in an otherwise stable population. The modelled total ranges from roughly 700,000 to 4.2 million, reflecting uncertainty about the starting population and its subsequent decline. The researchers could not reliably divide the total among disease, direct killings and deaths associated with dispossession and other colonial disruption.

The authors identify 1861 as the year with the most complete census information before 1971 and cite an Indigenous population estimate of 177,000 to 193,000 for that year. Their headline summary describes about 7% of the earlier population remaining; dividing that cited range by the median starting population of 2.22 million gives approximately 8% to 9%. The presentation therefore includes both a modelled summary and a historical population range.

For readers, the central finding is the scale of the collapse: the researchers reconstruct a continent with millions of Indigenous inhabitants before invasion, followed by a population reduced to a small fraction of that size within several generations.

Disease, violence and the loss of Country

Smallpox struck the Sydney region in 1789, within 15 months of the First Fleet's arrival. Related modelling cited by the authors estimates that the epidemic could have killed up to 220,000 Indigenous people in south eastern Australia.

Co-author Corey Bradshaw, a professor of global ecology at Flinders University, also described possible smallpox deaths of up to 220,000 along the east coast during the first decade of colonisation. Further outbreaks occurred in 1826 to 1838 and 1860 to 1869. Measles, influenza, tuberculosis and other introduced diseases added to the losses.

Colonial expansion also brought frontier killings and the removal of people from Country. The authors describe restrictions on obtaining food, forced and exploitative labour, family separation, malnutrition and damaging assimilation policies. These pressures overlapped: losing access to food and shelter could leave communities less able to withstand disease.

Bradshaw said recorded massacres could be an order of magnitude below the actual number, meaning roughly a factor of ten. He presented that as an assessment of how much violence escaped documentation. The authors note that the Colonial Frontier Massacres database records hundreds of incidents meeting strict evidentiary criteria.

The study carries a warning that its content may be confronting and distressing. Indigenous readers seeking support in Australia can contact 13YARN on 13 92 76, available at all hours with Aboriginal or Torres Strait Islander crisis supporters.

The dates behind the population collapse

The research brings together events separated by more than two centuries. Its historical reconstruction begins in 1788, while its assessment of recovery draws on modern census records and a conditional projection to 2047.

• 1788: The First Fleet arrives. Researchers estimate a median Indigenous population of 2.22 million before invasion.
• 1789: A major smallpox epidemic strikes the Sydney region.
• 1861: Early census information places the Indigenous population between 177,000 and 193,000.
• Around 1930: Radcliffe-Brown publishes the low population estimate that influences later accounts.
• 1971: The authors identify the first comprehensive census of Indigenous Australians.
• 2021: The Census records 812,728 people identifying as Aboriginal and/or Torres Strait Islander.
• 15 September 2026: The study is published in Nature Human Behaviour.
• Around 2047: The researchers project a return to 2.22 million if current population growth trends continue.

The projection depends on future growth following those trends. Births, deaths and changes in census identification will shape how population numbers develop.

Why the 2021 figures need explanation

The 2021 Census count of 812,728 is about 36.6% of 2.22 million, explaining the researchers' rounded comparison of 37%. A census count records people through the census process; the Australian Bureau of Statistics also produces an estimated resident population using census results and demographic adjustments.

The bureau's final 2021 population estimates, released on 31 August 2023, put the Aboriginal and Torres Strait Islander population at 983,709 on 30 June 2021. That was 3.8% of Australia's total population and about 44.3% of the study's median estimate for 1788.

The adjusted estimate is 170,981 higher than the census count cited by the researchers. Both describe 2021, but they are different statistical measures. The bureau's estimate uses final census data and finalised components for births, deaths and migration.

The bureau also says growth between the 2016 and 2021 Census counts cannot be explained entirely by demographic factors. Changes in whether people are recorded as Aboriginal or Torres Strait Islander contribute to changes in counts, alongside births and deaths. That matters when using recent growth to project a future population.

What recovery looks like today

Aboriginal and Torres Strait Islander Australians had a median age of 24 in 2021, compared with 38.9 for non-Indigenous Australians, according to the bureau. About 33.1% were younger than 15, compared with 17.9% of the non-Indigenous population.

The bureau links this younger age structure to higher birth rates and lower life expectancy. People aged 65 and over made up 5.4% of the Indigenous population, compared with 17.2% of the non-Indigenous population. Population growth therefore sits alongside continuing differences in survival and health.

New South Wales, Queensland and Western Australia together accounted for 74.5% of the Indigenous population. The Northern Territory had the largest Indigenous share of its own population, at 30.8%. More than a third of Indigenous Australians lived in major cities, while 15.4% lived in remote or very remote areas.

These figures give a concrete picture of the communities whose survival the researchers describe. Reaching a historical population total is one measure of demographic recovery; present needs also depend on age, health and where people live.

Land management, truth telling and survival

Millions of Indigenous people managing Country would have sustained cultural burning, resource management and networks of knowledge across Australia at a much larger scale than low population estimates suggest, the authors argue. The loss of people also disrupted land management practices developed over thousands of years.

The researchers connect that history with efforts to support land management led by Indigenous communities. They also point to the National Agreement on Closing the Gap, which recognises that Indigenous peoples must share decisions and help design policies affecting them.

Co-author Lynette Russell, a distinguished professor at Monash University, called for recognition of intergenerational privilege alongside intergenerational trauma and disadvantage. Her argument connects the losses experienced by Indigenous families with advantages passed through other families following colonisation.

The team's institutional research announcement also places survival at the centre of the findings. Larissa Behrendt, a University of Technology Sydney professor, Eualayai/Gamillaroi woman and chair of the research centre's advisory committee, said:

Our survival is one of Australian history's most remarkable stories.

Indigenous communities continued transmitting language, culture, kinship and responsibilities to Country despite deaths and dispossession. The research seeks to measure the scale of the loss while recognising the people and knowledge that endured.

Key Points

• The study estimates a median Indigenous population of 2.22 million before British colonisation in 1788, within a likely range of roughly 1 million to 4 million.
• Genetic evidence and environmental modelling underpin the central estimate, alongside a wider review including more than 5,000 archaeological radiocarbon dates.
• The model estimates 2.06 million excess deaths between 1788 and 1861, with a range of roughly 700,000 to 4.2 million.
• The 2021 Census count was about 37% of the estimated population in 1788; the bureau's adjusted resident population estimate was about 44%.
• A return to 2.22 million around 2047 depends on current population growth trends continuing.
• The authors connect the findings with truth telling, Indigenous participation in policy and support for cultural and land management knowledge.