Archive for the ‘paleoclimate’ Category

Neanderthal teeth reveal lead exposure and difficult winters

October 31st, 2018
Neanderthal teeth reveal lead exposure and difficult winters

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A new study of oxygen isotope ratios and heavy metals in the tooth enamel of Neanderthals who lived and died 250,000 years ago in southeast France suggests that they endured colder winters and more pronounced differences between seasons than the region’s modern residents. The two Neanderthals in the study also experienced lead exposure during their early years, making them the earliest known instances of this exposure.

Enduring harsh winters

Tooth enamel forms in thin layers, and those layers record the chemical traces of a person’s early life—from climate to nutrition to chemical exposures—a little like tree rings on a much smaller scale. Archaeologist Tanya Smith of Griffith University and her colleagues examined microscopic samples of tooth enamel from two Neanderthal children from the Payre site in southeastern France. The teeth were radiocarbon dated to around 250,000 years ago, and the set of samples recorded about three years of life.

One important clue to past environments is oxygen, which comes from the water a person drank or the plants they ate. The ratio of the oxygen-18 isotope to oxygen-16 depends on temperature, precipitation, and evaporation. Generally, higher ratios of oxygen-18 indicate warmer, drier conditions with more evaporation.

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Posted in Archaeology, biological archaeology, isotope analysis, Neanderthals, paleoanthropology, paleoclimate, science, teeth | Comments (0)

Archaeologists find 300,000-year-old stone tools in Saudi Arabia

October 29th, 2018
Archaeologists find 300,000-year-old stone tools in Saudi Arabia

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Stone tools unearthed in Saudi Arabia’s inhospitable Nefud Desert indicate that members of our genus Homo had ventured beyond the familiar borders of Africa and the Levant sometime between 300,000 and 500,000 years ago. And according to climate data captured in the bones of animals found at the site, the environment they moved into may not have been that different from the one they left behind in East Africa. That may help anthropologists better understand the role of environment—and the ability to adapt to challenging new landscapes—in shaping human evolution and global expansion.

The things they left behind

Archaeologist Patrick Roberts of the Max Planck Institute for the Science of Human History and his colleagues recently discovered a handful of stone tools in a sandy layer of soil beneath the dry traces of a shallow Pleistocene lake at Ti’s al Ghadah, in the Nefud Desert of northern Saudi Arabia. The soil layer dated to between 300,000 and 500,000 years ago, and it also contained fossilized remains of grazing animals, water birds, and predators like hyena and jaguar. Many of the bones seem to bear the marks of butchering by tool-wielding hominins.

Archaeologists had found other fossils at the site with possible cut marks, but, without stone tools, it’s difficult to determine if a notch in a fossil rib was put there by a human hand and not another predator or natural process. The tools—six sharp brown chert flakes and a scraper—make a much clearer case. Roberts and his colleagues say they’re the oldest radiometrically dated hominin artifacts in the Arabian Peninsula, edging out the previous contender by 100,000 years.

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Posted in anthropology, arabian peninsula, Archaeology, fossil record, homo erectus, human ancestors, human migration, out of africa, paleoanthropology, paleoclimate, paleoecology, Saudi Arabia, science, Stable isotope, stone tools | Comments (0)