Large estimated size of the Australian Indigenous population before its extensive decline following colonial invasion

Estimating the size of Indigenous populations in Australia before European colonial invasion is invaluable to truth-telling and reconciliation. Robust estimates of the population dynamics of pre-colonial Indigenous Australians are poor owing to lethal diseases, frontier and structural violence, and absence of systematic censuses. Here we review ethnographic observations, archaeological and genetic reconstructions, and modelled carrying capacity to infer Indigenous population size before colonial invasion. Congruency of the modelled and genetics-based (not historical or ethnographic accounts) estimates suggests a bootstrapped pre-colonial median of 2.22 million, or 0.29 people km^-2. This allows an estimate of the number of excess deaths in the post-colonial era. For a median pre-colonial population of 2.22 million, ~28,200 excess deaths per year (2.06 million deaths in total) would have had to occur over the late eighteenth and early nineteenth centuries from colonial invasion-related mortality to align with census records. These estimates speak to how the aftermath of invasion was experienced by Indigenous Australians, and recent census records show their survival and recovery since. We warn readers that the content of this study is confronting and possibly distressing.