The chronology of the Inca Empire has traditionally relied on ethnohistoric dates, which suggest that a northern expansion into modern Ecuador began in AD 1463 and a southern expansion into modern Argentina began in AD 1471. We test the validity of these dates with two Bayesian models, which show that the ethnohistoric dates are incorrect and that the southern expansion began before the northern one. The first model of seven dates shows that the site of Chamical, Ecuador, was first occupied cal AD 1410–1480 (95% probability) and has a high probability of being built prior to the ethnohistoric date. The second is an outlier model of 26 14C dates and 19 thermoluminescence (TL) dates from 10 sites along the empire’s southeastern limit in northwestern Mendoza, Argentina. Here, the Inca occupation began cal AD 1350–1440 (95% probability), also earlier than the ethnohistoric date. The model also suggests that the Inca occupation of Mendoza lasted 70–230 yr (95% probability), longer than previously thought, which calls for new perspectives on the timing and nature of Inca conquests and relationships with local groups. Based on these results, we argue it is time to abandon the traditional chronology in favor of Inca chronologies based on Bayesian models.

Tombs and cairns present a dating challenge when the human remains are unstratified, incomplete and dispersed. By considering the distribution of time intervals between deaths as a possible a priori condition of multiple burials of select groups, a Bayesian model is suggested that may constrain the uncertainty date range of the group. The method may also address the wide uncertainties seen in radiocarbon calibration on a calibration curve plateau. The mathematical justification for the choice of Log Normal intervals, between death events, is first presented, followed by worked examples that compare the treatment of groups of 22 dates using Phase then Sequence with interval gaps. Finally, scenarios of potential Select Groups are examined, to demonstrate the efficacy of this alternative heuristic model to current model treatments.

The Neolithic chambered cairn at Knowe of Rowiegar, Rousay, Orkney, was excavated in 1937 as part of a campaign that also saw excavations at sites such as Midhowe and the Knowe of Lairo. Not fully published at the time, and with only partial studies since, the human bone assemblage has now been largely re-united and investigated. This included an osteological study and AMS dating of selected bones from this site and other Rousay cairns in the care of University of Aberdeen Museums, as well as the use of archival sources to attempt a reconstruction of the site. It is suggested that the human remains were finally deposited as disarticulated bones and that the site was severely damaged at the time the adjacent Iron Age souterrain was constructed. The estimation of the minimum number of individuals represented in the assemblage showed a significant preponderance of crania and mandibles, suggesting the presence of at least 28 heads, along with much smaller numbers of other bones, while age and sex determinations showed a preponderance of adult males. Seven skulls showed evidence of violent trauma, while evidence from both bones and teeth indicates that there were high levels of childhood dietary deficiency. Although detailed analysis of the dates was hampered by the ‘Neolithic plateau’, a Bayesian analysis of the radiocarbon determinations suggests the use of the site during the period 3400 to 2900 cal bc. This is shown to be similar to that of other dated Orcadian Neolithic cairns and may represent different responses to two periods of severe climate deterioration.