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Archaeological studies of pre-historic Arctic cultures are often limited to artefacts and architecture; such records may be incomplete and often do not provide a continuous record of past occupation. Here, we used lake sediment archives to supplement archaeological evidence to explore the history of Thule and Dorset populations on Somerset Island, Nunavut (Canada). We examined biomarkers in dated sediment cores from two ponds adjacent to abandoned Thule settlements (PaJs-3 and PaJs-13) and compared these to sediment cores from two ponds without past human occupation. Coprostanol and epicoprostanol, δ15N measurements, sedimentary chlorophyll a and the ratio of diatom valves to chrysophyte cysts were elevated in the dated sediment profiles at both sites during Thule and Dorset occupations. Periods of pronounced human impact during the Thule occupation of the site were corroborated by 14C-dated caribou bones found at both sites that identified intense caribou hunting between ca 1185 and 1510 CE. Notably, these sediment core data show evidence of the Dorset occupation from ca 200 to 500 CE at sites where archaeological evidence was heretofore lacking. We highlight the utility of lake sediments in assisting archaeological studies to better establish the timings, peak occupations and even lifestyle practices of the Dorset and Thule Arctic peoples. [ABSTRACT FROM AUTHOR]

Historically, many high‐elevation lakes in the tropical Andes have been observed to mix frequently, with rare, brief periods of thermal stratification. As temperatures have risen in the Andes over the past several decades, thermistor data have shown that many lakes are now experiencing longer periods of thermal stratification with resultant ecological restructuring. Palaeolimnological studies from these lakes have recorded striking diatom assemblage shifts, coeval with recent changes in thermal stratification.Here, we analyse subfossil diatom assemblages from a wind‐sheltered lake, Laguna Yanacocha, in the Peruvian Andes. Thermistors deployed in the lake indicated that Laguna Yanacocha was more strongly thermally stratified and for longer periods than other nearby lakes. We hypothesised that, owing to its sheltered position, this lake is likely to have exhibited enhanced periods of thermal stratification even before the period of recent warming, and that these limnological conditions would be tracked in the subfossil diatom record.The diatom assemblages from Laguna Yanacocha recorded consistently high abundances of the obligate planktonic taxon Discostella stelligera over the last several centuries. This taxon is known to flourish with warming and has been shown to increase in abundance with the onset of thermally stratified conditions in other Andean waterbodies, as well as lakes globally. The dominance of D. stelligera throughout the entire sediment record suggests a long history of thermal stratification that is likely to be a consequence of the study lake's surrounding topography, which shelters it from wind mixing.The sub‐fossil assemblage data from Laguna Yanacocha contrasts with assemblages from previously studied wind‐swept lakes in the Andes, which primarily show low abundances of D. stelligera before well‐documented temperature increases. The fossil diatom record from Laguna Yanacocha may provide an indication of how other lakes from the region will respond to warming temperatures and enhanced thermal stratification. [ABSTRACT FROM AUTHOR]

Archaeological studies of pre-historic Arctic cultures are often limited to artefacts and architecture; such records may be incomplete and often do not provide a continuous record of past occupation. Here, we used lake sediment archives to supplement archaeological evidence to explore the history of Thule and Dorset populations on Somerset Island, Nunavut (Canada). We examined biomarkers in dated sediment cores from two ponds adjacent to abandoned Thule settlements (PaJs-3 and PaJs-13) and compared these to sediment cores from two ponds without past human occupation. Coprostanol and epicoprostanol, δ 15 N measurements, sedimentary chlorophyll a and the ratio of diatom valves to chrysophyte cysts were elevated in the dated sediment profiles at both sites during Thule and Dorset occupations. Periods of pronounced human impact during the Thule occupation of the site were corroborated by 14 C-dated caribou bones found at both sites that identified intense caribou hunting between ca 1185 and 1510 CE. Notably, these sediment core data show evidence of the Dorset occupation from ca 200 to 500 CE at sites where archaeological evidence was heretofore lacking. We highlight the utility of lake sediments in assisting archaeological studies to better establish the timings, peak occupations and even lifestyle practices of the Dorset and Thule Arctic peoples.

Understanding how animals respond to large-scale environmental changes is difficult to achieve because monitoring data are rarely available for more than the past few decades, if at all. Here, we demonstrate how a variety of palaeoecological proxies (e.g. isotopes, geochemistry and DNA) from an Andean Condor ( Vultur gryphus ) guano deposit from Argentina can be used to explore breeding site fidelity and the impacts of environmental changes on avian behaviour. We found that condors used the nesting site since at least approximately 2200 years ago, with an approximately 1000-year nesting frequency slowdown from ca 1650 to 650 years before the present (yr BP). We provide evidence that the nesting slowdown coincided with a period of increased volcanic activity in the nearby Southern Volcanic Zone, which resulted in decreased availability of carrion and deterred scavenging birds. After returning to the nest site ca 650 yr BP, condor diet shifted from the carrion of native species and beached marine animals to the carrion of livestock (e.g. sheep and cattle) and exotic herbivores (e.g. red deer and European hare) introduced by European settlers. Currently, Andean Condors have elevated lead concentrations in their guano compared to the past, which is associated with human persecution linked to the shift in diet.