By Bruce Bower
Homo erectus reached the Indonesian island of Java some 300,000 years later than many researchers have assumed, a new study finds.
Analyzing volcanic material from sediment that had yielded H. erectus fossils at Java’s Sangiran site shows that the extinct, humanlike hominids likely arrived on the island around 1.3 million years ago, scientists report in the Jan. 10 Science.
More than 100 H. erectus fossils have been found at Sangiran since 1936, many by local residents. For around the last 20 years, many researchers have accepted Sangiran sediment dates — based on analyses of the rate of decay of radioactive argon in volcanic rocks — that put H. erectus on the island from about 1.7 million until 1 million years ago. Others have disputed that timeline, saying the best evidence points to an H. erectus presence at Sangiran from between 1.3 million and 1.1 million years ago until roughly 600,000 years ago.
The new study supports that younger timeline. Researchers, led by paleoanthropologist Shuji Matsu’ura of the National Museum of Nature and Science in Tsukuba City, Japan, analyzed volcanic mineral grains, or zircons, from above, below and within sediment layers where H. erectus fossils had been found. One approach gauged the time since zircons had crystallized, and the other estimated the time since a volcanic eruption deposited zircons at Sangiran.