DD'eDeN aka note/nickname/alas_my_loves wrote:
https://theconversation-com.cdn.ampproject.org/v/s/theconversation.com/amp/revelations-from-17-million-year-old-ape-teeth-could-lead-to-new-insights-on-early-human-evolution-187996?amp_gsa=1&_js_v=a9&usqp=mq331AQKKAFQArABIIACAw%3D%3D#amp_tf=From%20%
251%24s&aoh=16612704419813&referrer=https%3A%2F%2Fwww.google.com&share=https%3A%2F%2Ftheconversation.com%2Frevelations-from-17-million-year-old-ape-teeth-could-lead-to-new-insights-on-early-human-evolution-187996
Cleaned up link:
https://theconversation.com/revelations-from-17-million-year-old-ape-teeth-could-lead-to-new-insights-on-early-human-evolution-187996
The timing and intensity of the seasons shapes life all around us,
including tool use by birds, the evolutionary diversification of giraffes,
and the behaviour of our close primate relatives.
Some scientists suggest early humans and their ancestors also
evolved due to rapid changes in their environment, but the physical
evidence to test this idea has been elusive – until now.
After more than a decade of work, we’ve developed an approach
that leverages tooth chemistry and growth to extract information
about seasonal rainfall patterns from the jaws of living and fossil
primates.
...
https://news.climate.columbia.edu/2022/08/22/17-million-year-old-ape-teeth-open-windows-into-prehuman-evolution/
17 Million-Year-Old Teeth Open Windows Into Early Ape and Human Evolution
An international team of scientists has shown in a new study that
fossil primate teeth can offer insights into the roles seasonal
climates and behaviors may have played in human and primate
evolution.
The study examined oxygen isotopes in teeth from a 17-million-year-old
site in northwest Kenya’s Turkana Basin. These included teeth from
an enigmatic large-bodied ape known as Afropithecus turkanensis.
The research was just published in the Proceedings of the National
Academy of Sciences,
To put the fossils into context, the researchers also measured oxygen
isotopes in modern primate teeth from across equatorial Africa, and
analyzed the isotopic signals they produced. The team, led by Daniel
Green, a postdoctoral scientist at Columbia University’s Climate School,
and Tanya Smith of Australia’s Griffith University, found that the
modern oxygen isotopes (natural variants of oxygen that differ by mass) recorded details of rainy seasons and droughts, environmental conditions
like altitude and vegetation, and variations in primate behavior.
...
https://www.pnas.org/doi/full/10.1073/pnas.2123366119
Fine-scaled climate variation in equatorial Africa revealed by modern
and fossil primate teeth
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.
Abstract
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 (δ18O 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 δ18O 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’ δ18O 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 δ18O 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.
--- SoupGate-Win32 v1.05
* Origin: fsxNet Usenet Gateway (21:1/5)