Estimating the size of the pre-colonial Indigenous population in Australia and the aftermath of European invasion

(includes code to compare predictions to anthropological/historical accounts, and a demographic model to estimate the number of excess deaths occurring from pre-colonial period to the late 19^th Century)

Focal manuscript

Williams, AN, R Tobler, B Griffiths, S Ulm, MC Nitschke, MI Bird, S Ingrey, F Saltré, K Beller, IJ McNiven, N Pitt, L Russell, A Paterson, C Wilson, CJA Bradshaw. Large size of the Australian Indigenous population prior to its massive decline following colonial invasion. Nature Human Behaviour In review

Abstract

Estimating the size of Indigenous populations in Australia prior to European colonial invasion is essential to truth-telling and reconciliation. Robust estimates of the population dynamics of pre-colonial Indigenous Australians are poor due to lethal diseases, frontier and structural violence, and no systematic censuses. We review ethnographic observations, archaeological and genetic reconstructions, and modelled carrying capacity, to infer Indigenous population size prior to colonial invasion. Congruency of the modelled (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 2.2 million, ~ 28,200 excess deaths year-1 (2.06 million deaths in total) would have had to occur over the late 18^th and early 19^th Centuries from colonial invasion-related mortality to align with census records. These findings highlight the major impacts of invasion experienced by Indigenous Australians, and demonstrate their remarkable survival, resilience, and recovery over recent centuries.

Scripts

R code by Corey Bradshaw (@cjabradshaw)

base script

• indigN.R: includes all code used to derive estimates reported in the paper mentioned above
• HGpopdensR: this is a separate repository that estimates population size using a different technique by Zhu et al. (2021)

source functions

• matrixOperators.r: functions for manipulating matrices for population projections
• new_lmer_AIC_tables3.r: functions to calculate information-theoretic parameters for linear models
• r.squared.r: functions to calculate goodness of fit for linear models

Data

• NppSahul(0-140ka_rawvalues)_Krapp2021.csv.zip: hindcasted net primary production (kg C m^-2 year^-1) for 0.5°×0.5° grid cells from 140 ka to the present for Sahul from Krapp et al. (2000) (unzip .csv file first)
• world2013lifetable.csv: age-specific human life-table values from Bradshaw & Brook (2014)
• bindensModelOverlay.csv: population estimates from Binford (2001) using R package binford (Marwick et al. 2016) overlayed on carrying-capacity estimates

R libraries

abind, bootstrap, binford, dismo, gbm, ggplot2, ncdf4, oceanmap, OceanView, performance, pracma, raster, rgl, sp, scatterplot3d, spatialEco, sjPlot, SpatialPack, spatstat, terra, truncnorm

Acknowledgements

The authors acknowledge the sovereign Traditional Owners and custodians (First Nations) of the unceded lands and seas where we live and work, including Bidiagal in Sydney (A.N.W., N.P.), Dharawal in Kamay/Botany Bay (K.B., S.I.), Dharawal in Woolungah/Wollongong (F.S.), Kulin Nation in Naarm/Melbourne (B.G., I.J.M., L.R.), Yirrganydji and Gimuy Walubara Yidinji in Gimuy/Cairns (S.U., M.I.B.), Ngunnawal and Ngambri in Galambary/Canberra (R.T.), Whadjuk Noongar of Boorloo/Perth (A.P.), Ngarrindjeri of Murrundi/lower Murray River, Kurangk/Coorong, and eastern Fleurieu Peninsula (C.W.), Palawa in Nipaluna/Hobart, lutruwitra/Tasmania (C.W.), Kaurna in Tarndanya/Adelaide (C.J.A.B., M.C.N., F.S.), and Peramangk in Bukatila/Mount Lofty Ranges (C.J.A.B.). The authors also acknowledge and recognise the deep historical and cultural harm our truth-telling exposes, and we commiserate sincerely with all First Nations peoples of Australia.

Funding

Funded jointly by the Australian Research Council Centre of Excellence for Indigenous and Environmental Histories and Futures (CE230100009), and the Australian Research Council Centre of Excellence for Australian Biodiversity and Heritage (CE17010001). L.R. supported by an Australian Research Council Laureate Fellowship (FL190100161). B.G. supported by an Australian Research Council Discovery Early Career Researcher Award (DE220100203).