Lead author Daniel Green examines fossil material from Kenya’s Turkana Basin.Īnother key finding of the team’s research is that studies of oxygen isotopes in fossil hominins-our ancestors-have thus far underestimated the chemical variations in their teeth. “Oxygen isotope compositions from Afropithecus and closely associated herbivores suggest that ape behavior and anatomy in this part of eastern Africa were shaped by seasonal environments long before the origin of hominins.” “The effects of climate variation on the earliest African apes are poorly understood, because detailed records of seasonal variation from this early period, the Miocene, are more sparse,” said Green. These results also suggested that specialized jaw adaptations-thick enamel and strong chewing muscles-would have helped Afropithecus consume hard foods during seasons of drought or resource scarcity. ![]() The researchers showed that the ancient apes experienced dry and wet seasons of variable intensity over time, possibly influenced by natural changes in Earth’s orbit around the sun. With the context provided by modern primates, the authors then analyzed teeth from Afropithecus found at a site called Kalodirr, and compared their results with 17 million-year-old rainfall patterns simulated by climate models. Working with primatologists, the researchers were able to ascertain that the teeth were forming when these climatic events occurred. ![]() Measurements from modern monkey teeth recorded an extended drought in one case in Ethiopia, and an extreme rainfall event in another case in Uganda. In the modern teeth, the researchers found that teeth could even indicate human alterations to the natural landscape, like the damming of a river, and document specific meteorological events. The arid, fossil-rich landscape of Kalodirr in the Turkana Basin region of Kenya, was once the forest home of the ancient ape Afropithecus 17 million years ago. 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. 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 research was just published in the Proceedings of the National Academy of Sciences, These included teeth from an enigmatic large-bodied ape known as Afropithecus turkanensis. ![]() The study examined oxygen isotopes in teeth from a 17-million-year-old site in northwest Kenya’s Turkana Basin. 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.
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