BOB HIRSHON (host):
Ancient equestrians. I’m Bob Hirshon and this is Science Update.
Humans may have domesticated horses 5600 years ago, in northern Kazakhstan, according to archaeologist Sandra Olsen at the Carnegie Museum of Natural History. She and her colleagues report finding evidence of ancient post holes arranged in large circles, corral-style. Within these rings, they found soil with increased levels of nitrogen, phosphorous and other elements consistent with levels found in horse manure.
In other geological news, researchers from the University of North Carolina in Chapel Hill report that the Amazon River once flowed westward into the Pacific, rather than east into the Atlantic, as it does today. They could track the flow by studying layers of tiny zircon crystals and how they grew. The scientists say that the mighty river reversed its flow over a hundred millions years ago, when the Andes Mountains formed in the west.
I’m Bob Hirshon, for AAAS, the Science Society.