January/February 2013 Issue

JAPAN: The radioactive carbon isotope 14C decays at a predictable rate. By measuring the carbon in ancient organic materials, you can tell how long the 14C has been decaying, and therefore how old the object is—radiocarbon dating. But the atmospheric concentration of 14C has not always been constant, so knowing past 14C concentrations is essential to refining accuracy. Tree rings, corals, and marine sediments are used for this. Now researchers have another resource—the sediments at the bottom of Lake Suigetsu are so clearly layered, year by year, that they will help improve the accuracy of radiocarbon dating for objects between 10,000 and 52,000 years old. —Samir S. Patel

CAMBODIA: The monuments of Angkor Wat include thousands of sandstone blocks—but where did they come from? Researchers recently undertook a study of the quarries used by the builders and identified more than 50 of them, active in different phases, about 20 miles northeast of the site, at the foot of Mt. Kulen. The team also investigated a canal-river system visible in satellite images, which they believe was used to transport the blocks to the site efficiently. —Samir S. Patel

TANZANIA: A case of childhood anemia indicates that early humans relied on meat as part of their diets as many as 1.5 million years ago—and sometimes did not get enough. In fragments of the skull of a two-year-old hominin, researchers found evidence of porotic hyperostosis, a condition associated with nutritional deficiencies related to a lack of meat consumption. The scientists conclude that people must have been hunting at the time, as scavenging would not have yielded enough meat to make it such an essential dietary need. —Samir S. Patel