Stable isotope evidence (Fe, Cu) suggests that sex, but not aging is recorded in rhesus macaque (Macaca mulatta) bone.

OBJECTIVES: Here, we examine (1) if the sex-related differences in iron (Fe) and copper (Cu) isotope ratios, represented as δ56 Fe and δ65 Cu values, respectively observed in humans exist in bulk occipital bone and incisors of male and female non-human primates, and (2) if the variation of Fe and Cu isotope ratios, known to vary in human blood as a factor of age are similar in non-human primate bone. MATERIALS AND METHODS: Isotope ratios were measured from the skeletal elements of 20 rhesus macaques (Macaca mulatta) with known life history traits. The metals were purified by column chromatography and their isotope ratios measured by MC-ICP-MS. Data were analyzed using generalized additive models (GAM). RESULTS: When accounting for age and sex independently, we found a significant relationship between δ65 Cu values and occipital bone, but not in incisors. There were no significant relationships observed between δ56 Fe values, occipital bone, or incisors. Similarly, there were no significant relationships observed between δ56 Fe values, δ65 Cu values, and age. DISCUSSION: We suggest that Cu and Fe isotope ratios have the potential to be useful supplementary tools in future research in biological anthropology, but additional studies are needed to further verify the relationship between sex, age, δ65 Cu, and δ56 Fe values in primates.

Strontium isotopes track female dispersal in Taï chimpanzees.

OBJECTIVES: Chimpanzees (Pan troglodytes) are patrilocal, with males remaining in their natal community and females dispersing when they reach sexual maturity. However, the details of female chimpanzee dispersal, such as their possible origin, are difficult to assess, even in habituated communities. This study investigates the utility of 87Sr/86Sr analysis for (1) assessing Sr baseline differences between chimpanzee territories and (2) identifying the status (immigrant or natal) of females of unknown origin within the territories of five neighboring communities in Taï National Park (Côte d'Ivoire). MATERIALS AND METHODS: To create a local Sr isoscape for the Taï Chimpanzee Project (TCP) study area, we sampled environmental samples from TCP-established territories (n = 35). To assess dispersal patterns, 34 tooth enamel samples (one per individual) were selected from the Taï chimpanzee skeletal collection. 87Sr/86Sr analysis was performed on all 69 samples at the W.M. Keck Lab. The theoretical density and overlap of chimpanzee communities as well as generalized linear mixed models (GLMMs) were used to test each question. RESULTS: 87Sr/86Sr ratios for natal male chimpanzees ranged from 0.71662 to 0.72187, which is well within the corresponding environmental baseline range of 0.70774-0.73460. The local Sr isoscapes fit was estimated with the root-mean-square error value, which was 0.0048 (22% of the whole 87Sr/86Sr data range). GLMMs identified significant differences in 87Sr/86Sr ratios between natal and unknown North community origin groups, suggesting that after 1980, females of unknown origin could be immigrants to North community (n = 7, z-ratio = -4.08, p = 0.0001, power = 0.94). DISCUSSION: This study indicates that 87Sr/86This study indicates that 87Sr/86Sr analysis can successfully identify immigrant females in skeletal collections obtained from wild chimpanzee communities, enabling the tracking of female dispersal patterns historically. There are, however, significant limitations within the scope of this study, such as (1) the absence of reliable maps for the TCP study area, (2) limited capacity for environmental sampling, (3) small sample sizes, and (4) tooth formation in wild chimpanzees.