期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：2022
卷号：119
期号：35
DOI：10.1073/pnas.2123366119
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：Significance
Environmental variability may have spurred unique adaptations among Miocene apes and later hominins, but this hypothesis has been impossible to test on the scale relevant to individual lifespans. We establish that oxygen isotope compositions in modern primate teeth record annual and semiannual seasonal rainfall patterns across a broad range of environments in equatorial Africa. We then document annual dry seasons experienced by the large-bodied Early Miocene ape
Afropithecus turkanensis, which may explain its novel dental adaptations and prolonged development. By revealing real-time historical and prehistoric environmental variation on a near weekly basis, we demonstrate that extraordinary behavioral and ecological variability can be recovered from modern and fossil African primates.
Variability in resource availability is hypothesized to be a significant driver of primate adaptation and evolution, but most paleoclimate proxies cannot recover environmental seasonality on the scale of an individual lifespan. Oxygen isotope compositions (δ
18O values) sampled at high spatial resolution in the dentitions of modern African primates (
n = 2,352 near weekly measurements from 26 teeth) track concurrent seasonal precipitation, regional climatic patterns, discrete meteorological events, and niche partitioning. We leverage these data to contextualize the first δ
18O values of two 17 Ma
Afropithecus turkanensis individuals from Kalodirr, Kenya, from which we infer variably bimodal wet seasons, supported by rainfall reconstructions in a global Earth system model.
Afropithecus’ δ
18O fluctuations are intermediate in magnitude between those measured at high resolution in baboons (
Papio spp.) living across a gradient of aridity and modern forest-dwelling chimpanzees (
Pan troglodytes verus). This large-bodied Miocene ape consumed seasonally variable food and water sources enriched in
18O compared to contemporaneous terrestrial fauna (
n = 66 fossil specimens). Reliance on fallback foods during documented dry seasons potentially contributed to novel dental features long considered adaptations to hard-object feeding. Developmentally informed microsampling recovers greater ecological complexity than conventional isotope sampling; the two Miocene apes (
n = 248 near weekly measurements) evince as great a range of seasonal δ
18O variation as more time-averaged bulk measurements from 101 eastern African Plio-Pleistocene hominins and 42 papionins spanning 4 million y. These results reveal unprecedented environmental histories in primate teeth and suggest a framework for evaluating climate change and primate paleoecology throughout the Cenozoic.
