Lush wetlands in Arabia lured waves of early humans out of Africa

[Judi Lynn]

Stone tools in ancient lakebeds show sequential expansions of different cultures

1 SEP 2021 11:55 AM
BY MICHAEL PRICE



Researchers excavated stone tools and animal bones from well-dated layers in ancient lakebeds, like this one at Jubbah oasis in northern Saudi Arabia.CERI SHIPTON/PALAEODESERTS PROJECT

If you know what to look for in dappled satellite images of desert—slight depressions, subtle color shifts—the dried-up ghosts of prehistoric lakes pop out against the sand fields of the Arabian Peninsula. Eight years ago, one ancient multihued lake in the Nefud Desert caught the eye of researchers. When scientists excavated its ancient shorelines, a new study reports, they found thousands of stone tools—and evidence that multiple waves of Homo sapiens and their relatives have been migrating across the Arabian interior for at least the past 400,000 years.

The results bolster the idea that the periodic greening of this typically harsh desert played a pivotal role in humans’ dispersals out of Africa—and provide the best evidence yet that different groups of humans pulsed out of the continent through the Sinai Peninsula, says Jessica Thompson, a paleoanthropologist at Yale University who wasn’t involved with the study. “Where there are lakes, there will be people,” she says. “They find their way there.”

Today, the sparsely populated Nefud is filled with wind-whipped sand dunes and spindly, drought-tolerant shrubs. But past excavations and paleoclimate models have revealed that over the past half-million years, brief periods of wetter, warmer conditions dumped seasonal rainfall over the region, turning its low basins into lakes and its ditches into rivers. In short order, the harsh desert became a lush grassland—a “green Arabia”—only to wither back to sand when arid weather inevitably returned.

In 2013, remote imaging specialists keyed in on several ancient lakebeds in the western Nefud in northern Saudi Arabia that appeared unusually colorful in satellite images. Archaeologist Michael Petraglia at the Max Planck Institute for the Science of Human History (SHH) suspected its marbled bands of sediment reflected several periods of draining and refilling.

More:
https://www.science.org/content/article/lush-wetlands-arabia-lured-waves-early-humans-out-africa