Ancient North American shoes step to fore.

By about 8,000 years ago, inhabitants of what is now the United States were making and wearing sophisticated sandals and slip-on shoes, according to researchers who analyzed a rare sampling of ancient footwear.

Prehistoric North Americans apparently fashioned shoes in regional styles using a variety of materials and techniques, contend archaeologist Michael J. O'Brien of the University of Missouri at Columbia and his coworkers.

O'Brien's group applied accelerator mass spectrometer (AMS) dating to 7 of 18 footwear specimens discovered more than 40 years ago in central Missouri's Arnold Research Cave.

"The design and weaving observed in the oldest specimen are about as complex as what we see in later ones that we've dated to around 1,000 years ago," O'Brien says. "These people knew exactly what they were doing."

Radiocarbon dating of sediment at the Missouri cave suggests that it was occupied as early as 11,000 years ago, O'Brien says. Researchers had not previously dated footwear at the site because the traditional radiocarbon method would have destroyed large portions of the items. The AMS technique uses tiny samples to measure the presence of different forms of carbon.

Two types of shoes appear in the Missouri collection. Most of the sandals have straps; the slip-ons generally have sides that hold the shoe on the foot. The footwear was constructed of plant fibers or, in two cases, leather.

The recent dating places the oldest specimen, a nearly complete sandal, at between 8,325 and 7,675 years old, the scientists report in the July 3 SCIENCE. It features a pointed toe, a sling-like heel formed out of twisted cords, and interlaced fibers in the sole. A braided cord apparently passed through side loops and over the foot and was tied at the ankle.

Other examples of ancient footwear, such as those attributed to the Anasazi in the U.S. Southwest around 1,000 years ago, exhibit few similarities to the Missouri finds, the researchers hold. Their results add to evidence of early advances in weaving and textile production in North America and elsewhere (SN: 5/23/98, p. 331).

For example, AMS dates extend back to as early as 9,000 years ago for sandals of a different style unearthed in Colorado, says Phil R. Gelb, a Navajo Nation archaeologist based in Flagstaff, Ariz. Similar analysis of intricately woven baskets previously found in Nevada, conducted by Catherine S. Fowler of the University of Nevada, Reno, places their age at about 9,400 years.