TEL AVIV, ISRAEL—Microscopic examination of five 120,000-year-old clamshells unearthed in Israel’s Qafzeh Cave detected striations around naturally occurring holes near their tops, according to an Ars Technica report. Daniella Bar-Yosef Mayer of Tel Aviv University and her colleagues suggest the marks indicate the shells once hung on a string. Additional wear around the edges of the shells may have been caused by the shells rubbing against each other. Four of the shells also retained traces of red ochre. The team members created their own shell jewelry and experimented with strings made from different kinds of fibers. They found that the marks left by string made with flax matched the marks on the prehistoric shells. Because 160,000-year-old shells from Israel’s Misliya Cave do not carry similar marks, Bar-Yosef Mayer and her colleagues suggest string was invented sometime between 160,000 and 120,000 years ago. The invention of string, she explained, would have led to raft-building, fishing nets, and more complicated animal traps, clothing, and bags. It is still not clear, however, if string was invented by modern humans or Neanderthals, she concluded. To read about Paleolithic stone balls found in Qesem Cave that wear analyses indicate were shaped by humans, go to "Around the World: Israel."