Long before social networks, text messages, phone calls or even the postal system, hunter-gatherers would communicate using eggshells.
- Engravings on ostrich eggshells reveal an early form of symbolic communication.
- These discoveries show that modern humans and Neanderthals made items holding symbolic meaning over 60,000 years ago.
Long before human communication evolved into incessant tapping on computer keys, people scratched on eggshells.
Don't laugh -- researchers say a cache of ostrich eggshells engraved with geometric designs demonstrates the existence of a symbolic communication system around 60,000 years ago among African hunter-gatherers.
The unusually large sample of 270 engraved eggshell fragments, mostly excavated over the past several years at Diepkloof Rock Shelter in South Africa, displays two standard design patterns, according to a team led by archaeologist Pierre-Jean Texier of the University of Bordeaux 1 in Talence, France.
Each pattern enjoyed its own heyday between approximately 65,000 and 55,000 years ago, the investigators report in a paper to be published this week in the Proceedings of the National Academy of Sciences.
Researchers already knew that the Howiesons Poort culture, which engraved the eggshells, engaged in other symbolic practices, such as engraving designs into pieces of pigment, that were considered to have been crucial advances in human behavioral evolution. But the Diepkloof finds represent the first archaeological sample large enough to demonstrate that Stone Age people created design traditions, at least in their engravings, Texier says.
Evidence of intentionally produced holes in several Diepkloof eggshells indicates that ancient people made what amounted to canteens out of them, a practice that researchers have documented among modern hunter-gatherers in southern Africa.
The engraved patterns probably identified the eggshells as the property of certain groups or communities, Texier proposes.
"The Diepkloof engravings were clearly made for visual display and recognized as such by a large audience comprising members of a community, and probably members of related communities," comments University of Bordeaux 1 archaeologist Francesco d'Errico, who was not involved in the new study.
D'Errico participated in the recent unearthing of 13 pieces of engraved pigment at South Africa's Blombos Cave dating to between 100,000 and 75,000 years ago. Along with perforated sea shells and other personal ornaments previously excavated in Africa and the Middle East, these discoveries show that items holding symbolic meaning were made more than 60,000 years ago by both modern humans and Neanderthals.
Even more exciting, according to archaeologist Curtis Marean of Arizona State University in Tempe, is the presence of drinking spouts in the South African eggshells. Water containers opened a new world of travel across arid regions for ancient people, he notes.
"The ability to carry and store water is a breakthrough technological advance, and here we have excellent evidence for it very early," Marean says. "Wow!"
Eggshell fragments from the oldest sediment layers at Diepkloof display a hatched-band motif. These engravings consist of two long, parallel lines intersected by varying numbers of short lines. Some specimens contain one hatched band, while others display remnants of two or three. Engravers always fashioned parallel lines first and then inserted regularly spaced intersecting lines, Texier says.
Eggshells from younger soil layers at Diepkloof contain patterns consisting of deeply engraved, parallel lines that sometimes converge or intersect. One eggshell fragment from these layers exhibits a different pattern -- slightly curved horizontal lines that cross a central, vertical line.
Of the many Howiesons Poort sites in southern Africa that have yielded ostrich eggshells, only Diepkloof shows evidence of stylistic engraving traditions, Texier says.