PANAMA CITY, PANAMA—Science Magazine reports that chemical analysis of the isotopes in animal bones unearthed in the ancient Maya city of Seibal determined which of the animals ate a diet rich in forest plant material, and were therefore wild, and which animals ate maize, and were therefore kept by humans. Archaeologist Ashley Sharpe of the Smithsonian Tropical Research Institute said dozens of turkeys, dogs, and one large cat that may have been a jaguar had all been fed maize-based diets. The bones of those dogs have been radiocarbon dated to between 450 and 300 B.C., making them the earliest known animals to have been domesticated by the Maya. These small, Chihuahua-like dog bones bore no signs of butchery, although Sharpe notes that doesn’t mean they weren't consumed. One pair of dogs from this period had isotope levels that suggested they had lived in Guatemala’s volcanic highlands before they were buried near a pyramid in Seibal’s central plaza. The cats, whose remains date to between 450 and 350 B.C., may have served a similar ceremonial use. The maize-fed turkeys lived between A.D. 175 and 950, at a time when dog remains became extremely scarce, indicating they could have replaced dogs as the Maya’s primary food source. For more on domestication of animals as food sources, go to “The Rabbit Farms of Teotihuacán.”