How did the giraffe get its long neck? That question has enthralled scientists for centuries. Charles Darwin assumed the driver of natural selection was food, as animals with longer necks could reach higher trees and have their own private food supply with little competition from other species. But a newly analyzed fossil of an ancient giraffe relative suggests there might be more to the story: Competition for mates could have also influenced neck evolution.
“It’s a cool story about an amazing sexual weapon,” says Ted Stankowich an evolutionary ecologist at California State University, Long Beach, who was not involved with the work.
In 1996, in a 15-million-year-old rock formation in China’s far northwest, paleontologists unearthed an unusual fossil with a braincase and some vertebrae. Its skull was thickened at the base, where it had been attached to an enlarged neck vertebra. Researchers first wondered whether it might be an ancient relative of cows or sheep but weren’t sure because its teeth and bones were so large, recalls Tao Deng, a paleontologist at the Chinese Academy of Sciences’s (CAS’s) Institute of Vertebrate Paleontology and Paleoanthropology. Only years later, when a CT scan revealed the inner ear bones of the “strange beast,” did they realize it was a giraffoid, one of a group of animals that includes today’s okapi and giraffes and several other extinct giraffelike species.
