Posted on Saturday 6 January 2007

From the FAQ

Where are the balls found?

They were originally found in the delta of the Térraba River, also known as the Sierpe, Diquís, and General River, near the towns of Palmar Sur and Palmar Norte. Balls are known from as far north as the Estrella Valley and as far south as the mouth of the Coto Colorado River. They have been found near Golfito and on the Isla del Caño. Since the time of their discovery in the 1940s, these objects have been prized as lawn ornaments. They were transported, primarily by rail, all over Costa Rica. They are now found throughout the country. There are two balls on display to the public in the U.S. One is in the museum of the National Geographic Society in Washington, D.C. The other is in a courtyard near the Peabody Museum of Archaeology and Ethnography, at Harvard University in Cambridge, Massachusetts.

How were they made?

The balls were most likely made by reducing round boulders to a spherical shape through a combination of controlled fracture, pecking, and grinding. The granodiorite from which they are made has been shown to exfoliate in layers when subjected to rapid changes in temperature. The balls could have been roughed out through the application of heat (hot coals) and cold (chilled water). When they were close to spherical in shape, they were further reduced by pecking and hammering with stones made of the same hard material. Finally, they were ground and polished to a high luster. This process, which was similar to that used for making polished stone axes, elaborate carved metates, and stone statues, was accomplished without the help of metal tools, laser beams, or alien life forms.

Who made them?

The balls were most likely made by the ancestors of native peoples who lived in the region at the time of the Spanish conquest. These people spoke Chibchan languages, related to those of indigenous peoples from eastern Honduras to northern Colombia. Their modern descendants include the Boruca, Téribe, and Guaymí. These cultures lived in dispersed settlements, few of which were larger than about 2000 people. These people lived off of fishing and hunting, as well as agriculture. They cultivated maize, manioc, beans, squash, pejibaye palm, papaya, pineapple, avocado, chile peppers, cacao, and many other fruits, root crops, and medicinal plants. They lived in houses that were typically round in shape, with foundations made of rounded river cobbles.

How old are they?

Stone balls are known from archaeological sites and buried strata hat have only pottery characteristic of the Aguas Buenas culture, whose dates range from ca. 200 BC to AD 800. Stone balls have reportedly been found in burials with gold ornaments whose style dates from after about AD 1000. They have also been found in strata containing sherds of Buenos Aires Polychrome, a pottery type of the Chiriquí Period that was made beginning around AD 800. This type of pottery has reportedly been found in association with iron tools of the Colonial period, suggesting it was manufactured up until the 16th century. So, the balls could have been made anytime during an 1800-year period. The first balls that were made probably lasted for several generations, during which time they could have been moved and modified.