The child from Dikika
On December 10, 2000, paleoanthropologist Zeresenay Alemseged spotted the fossilized face of a small child embedded in a block of sandstone in the Dikika region of Ethiopia. The discovery was the beginning of a years-long, painstaking excavation to free one of the most complete early hominin skeletons ever found. The fossil, officially cataloged as DIK-1-1, is dated to 3.3 million years ago. Nicknamed "Selam," meaning "peace" in Amharic, she belongs to the species Australopithecus afarensis—the same as the famous "Lucy" fossil, though Selam is about 120,000 years older.
The fossil's remarkable preservation is likely due to a rapid burial during a flood. Selam was a three-year-old female at the time of her death, an age determined by her dental development. The skeleton includes an almost complete skull, the full spinal column, the torso, and parts of the limbs. Extracting these fragile bones from the surrounding sandstone was a delicate process that took nearly five years. CT scans of the skull provided a detailed look at her developing teeth and brain. The brain volume was about 330 cubic centimeters, similar to a chimpanzee of the same age. Analysis suggests that brain growth in A. afarensis was slower than in chimps, indicating a shift toward a more human-like, extended childhood.
A body built for two worlds
Selam’s skeleton shows a mosaic of traits for both upright walking and tree climbing. Her leg bones, including the femur and tibia, confirm that A. afarensis was bipedal on the ground. The structure of her spine, with 12 thoracic vertebrae and 12 pairs of ribs, is also more human-like than ape-like. This configuration, enabling efficient walking, was established much earlier in the human lineage than previously known.
Her upper body retained features well-suited for an arboreal life. Her shoulder blades, or scapulae, are nearly identical to those of a young gorilla, with an upward-pointing socket joint that is advantageous for climbing and suspension. Her finger bones are long and curved, another feature for grasping branches. This combination of features suggests A. afarensis lived a double life, walking on the ground but likely taking to the trees for foraging or to escape predators.
The most exceptional part of the find is a tiny, U-shaped bone from her neck: the hyoid. It is the first and only hyoid bone found from any early human ancestor. Its shape is distinctly more like that of a chimpanzee or gorilla than a modern human. This morphology suggests Selam's vocal tract was ape-like and not built for the complex sounds of human speech.