The degradation of natural ecosystems worldwide and the accompanying loss of plant and animal species essential for their maintenance, results primarily from human expansion and exploitation. But this is not a new phenomenon, for populations of Homo sapiens migrating out of Africa during the late Quaternary precipitated waves of extinctions across most of the globe. Despite the consensus regarding the general pattern of Homo sapiens colonisation, the paths taken by modern humans out of Africa have been the subject of considerable debate over the past two decades, such as whether (i) humans could have entered the Americas via a different route than the northwestern American ‘ice-free corridor’, or (ii) human colonisation of Australia might have followed multiple, well-watered routes to occupy most of the continent only a few thousand years after first entry. Even reliable and comprehensive archaeological evidence is unlikely to reveal the true timing of human presence in an area due to a bias introduced by incomplete sampling or taphonomy; the first evidence of Homo sapiensin a region according to the archaeological record is insufficient to identify the true timing of first colonisation.
We developed a statistical method to correct the bias in the archaeological evidence to estimate the regional colonisation patterns of the first Homo sapiens. We applied this method to a compilation of various published and quality-rated archaeological datasets encompassing Eurasia, Australia and North America. We analysed the agreement and discrepancies between model estimates and worldwide human colonisation patterns inferred from genetic data.
Results/Conclusions
By focusing our results on both Australia and North America, we found that (i) ~ 50,000 years ago, the first modern human entered Australia from the western side of the continent, (ii) colonisation trajectories inferred from our model support the hypothesis that human colonisation across Australia might have been related to the connectivity between small, permanent water points, and (iii) the first Americans likely travelled from eastern Eurasia to North America through Beringia using a coastal route rather than an inland ice-free corridor ~ 16,000 years ago.