The ancient stone spheres（球体） of Costa Rica were made world-famous by the opening sequence of "Raiders of the Lost Ark（夺宝奇兵） ," when a mockup（实物模型） of one of the mysterious relics（遗迹） nearly crushed Indiana Jones. So perhaps John Hoopes is the closest thing at the University of Kansas to the movie action hero.

Hoopes, associate professor of anthropology（人类学） and director of the Global Indigenous Nations Studies Program, recently returned from a trip to Costa Rica where he and colleagues evaluated the stone balls for UNESCO（联合国教科文组织） , the United Nations cultural organization that might grant the spheres World Heritage Status.

His report will help determine if sites linked to the massive orbs（魔法球） will be designated for preservation and promotion because of their "outstanding value to humanity."

Hoopes, who researches ancient cultures of Central and South America, is one of the world's foremost（最先的） experts on the Costa Rican spheres. He explained that although the stone spheres are very old, international interest in them is still growing.

"The earliest reports of the stones come from the late 19th century, but they weren't really reported scientifically until the 1930s — so they're a relatively recent discovery," Hoopes said. "They remained unknown until the United Fruit Company began clearing land for banana plantations in southern Costa Rica."

According to Hoopes, around 300 balls are known to exist, with the largest weighing 16 tons and measuring eight feet in diameter. Many of these are clustered（聚合，成群） in Costa Rica's Diquis Delta region. Some remain pristine（原始的） in the original places of discovery, but many others have been relocated or damaged due to erosion（侵蚀，腐蚀） , fires and vandalism.

The KU researcher said that scientists believe the stones were first created around 600 A.D., with most dating to after 1,000 A.D. but before the Spanish conquest.

"We date the spheres by pottery（陶器） styles and radiocarbon（放射性碳） dates associated with archeological（考古学的） deposits found with the stone spheres," Hoopes said. "One of the problems with this methodology（方法学，方法论） is that it tells you the latest use of the sphere but it doesn't tell you when it was made. These objects can be used for centuries and are still sitting where they are after a thousand years. So it's very difficult to say exactly when they were made."

Speculation（推测，思索） and pseudoscience（伪科学，假科学） have plagued（折磨，困扰） general understanding of the stone spheres. For instance, publications have claimed that the balls are associated with the "lost" continent of Atlantis. Others have asserted that the balls are navigational aids or relics related to Stonehenge or the massive heads on Easter Island.