The length of the human generation interval is a key parameter when using genetics to date population divergence events. However, no consensus exists regarding the generation interval length, and a wide variety of interval lengths have been used in recent studies. This makes comparison between studies difficult, and questions the accuracy of divergence date estimations. Recent genealogy-based research suggests that the male generation interval is substantially longer than the female interval, and that both are greater than the values commonly used in genetics studies. This study evaluates each of these hypotheses in a broader cross-cultural context, using data from both nation states and recent hunter-gatherer societies. Both hypotheses are supported by this study; therefore, revised estimates of male, female, and overall human generation interval lengths are proposed. The nearly universal, cross-cultural nature of the evidence justifies using these proposed estimates in Y-chromosomal, mitochondrial, and autosomal DNA-based population divergence studies.

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This study uses strontium ( 87 Sr/ 86 Sr), oxygen (δ 18 O) and carbon (δ 13 C) isotope analysis of archaeological tooth enamel samples to investigate the origins of human remains from two sites in Arnhem Land, Northern Territory: a coastal Macassan site and an Indigenous rockshelter complex. The study aims to resolve whether two individuals from the Macassan site originate from outside Arnhem Land and, if so, whether their place of origin can be determined. Strontium results confirm the Macassan and Indigenous samples represent two distinct populations. The Indigenous values match the local Arnhem Land geologic strontium signatures, while the Macassan values are outside the local range and more likely to match Indonesian geological signatures. Carbon isotope results are more equivocal, but tend to support the presence of two populations by revealing slightly different dietary backgrounds for each group. Oxygen isotope data introduce more complexity; their geographic signal may be confounded by cultural behaviour. Radiocarbon dating suggests the Macassan Anuru Bay A site is a relatively early contact site.This study shows that even with a small sample set there is potential to discern past human mobility and origin using stable isotope analysis.

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