What do Homo sapiens have that our hominid ancestors did not? Many researchers think that the capacity for symbolic behaviors—such as art and language—is the hallmark of our species. A team working in South Africa has now discovered what it thinks is some of the best early evidence for such symbolism: a cache of ostrich eggshells dated to about 60,000 years ago and etched with intricate geometric patterns.

This fits with other recent suggestions of symbolism from South Africa. For example, last year researchers reported pieces of ochre etched with what may be abstract designs …