Monthly mobility inferred from isoscapes and laser ablation strontium isotope ratios in caprine tooth enamel

Abstract

Strontium isotopic analysis of sequentially formed tissues, such as tooth enamel, is commonly used to study provenance and mobility of humans and animals. However, the potential of 87Sr/86Sr in tooth enamel to track high-frequency movements has not yet been established, in part due to the lack of data on modern animals of known movement and predictive model of isotope variation across the landscape. To tackle this issue, we measured the 87Sr/86Sr in plant samples taken from a 2000 km2 area in the Altai Mountains (Mongolia), and the 87Sr/86Sr in tooth enamel of domestic caprines whose mobility was monitored using GPS tracking. We show that high-resolution, sequential profiles of strontium isotope composition of tooth enamel reliably reflect the high-frequency mobility of domestic livestock and that short-term residency of about 45 days can be resolved. This offers new perspectives in various disciplines, including forensics, ecology, palaeoanthropology, and bioarchaeology.

Diachronic forager mobility: untangling the Stone Age movement patterns at the sites Norje Sunnansund, Skateholm and Västerbjers through strontium isotope ratio analysis by laser ablation

“…By micro-sampling a tooth, multiple times at an equal enamel depth, from tip to cervix, it is possible to study the measurement pattern and obtain chronologically ordered data where each measurement represents a few weeks of strontium uptake incorporated in spot-specific enamel mineralization (Boethius et al 2022). If correlated with bioavailable strontium ratios, it is thus possible to follow the mobility of both humans and animals (Boethius et al 2022;Lazzerini et al 2021).…”

Tracing the mobility of a Late Epigravettian (~ 13 ka) male infant from Grotte di Pradis (Northeastern Italian Prealps) at high-temporal resolution

“…It is worth noting that variations in Sr content and isotope compositions of the different reservoirs, physiology and selective feeding behaviors may complicate the interpretation of high-resolution Sr isotopic profiles, as recently suggested for caprids 53 . It is also noteworthy that along the tooth growth, the 87 Sr/ 86 Sr profile shows changes in the slope of the variation, as shown by the first derivative of the mean normalized data (Fig.…”

“…5 ). Deriving such data helps visualizing and quantifying the variability along time-series profiles and evaluating possible mobility patterns 53 . In particular, the largest changes in the first derivative are evident pre-natally and during the first weeks after birth for Pradis 1 (but see also Fumane 2 and Nadale 1 from Nava et al 12 , Fig.…”

Silver Linings at the Dawn of a “Golden Age”

“…These records of movement from free ranging organisms could come from the application of GPS, radio collars, satellite tracking, and drones which are also rapidly advancing technologies. For example, expected 87 Sr/ 86 Sr of GPS-collared animals could be reconstructed and compared to isotope profiles recorded in the same individuals' teeth, tusks, antlers, or possibly hair (e.g., Lazzerini et al, 2021). Integration of these approaches with movement models, such as those borrowed from spatial ecology, is perhaps the next natural step in reconstructing the movement of people and animals in the past (e.g., see discussion in Britton, 2017, and the PleistoHERD project webpage 1 ).…”