Scientists Discover Remains of a Baby With a Nearly Complete Skull, It's 150,000 Years Older Than the Lucy Specimen

Scientists in Ethiopia have discovered the incredibly well-preserved remains of a three-year-old child, 3.3 million years old, considered the oldest and most complete juvenile human ancestor ever found, stated NPR. The fossil is known as the Dikika child or "Selam," which is of the same species as the famous Lucy specimen but 150,000 years older. "I realized the significance of the fossil," said Zeresenay Alemseged of the Max Planck Institute in Germany, who headed the discovery, stated NPR. "But what we had then was only the upper part of the body -- including the skull." The painstaking excavation process took Alemseged and his team five years of careful work, meticulously removing sandstone grain by grain using dental tools.

The discovery has left researchers astounded because of its exceptional preservation. Bernard Wood, an anthropologist at George Washington University, vividly remembered the first look he got at the skeleton: "He took this thing out of his safe and I was just sort of standing there with my jaw dropping somewhere around my knees. It's just the most remarkable thing to see," according to NPR. The skeleton is unprecedented in the detail it preserved—a complete skull, upper and lower jaws with baby teeth and adult teeth inside, ribs, finger bones, even those rare elements, shoulder blades, and kneecaps no bigger than macadamia nuts. This level of preservation offers scientists an extraordinary window into early human development.

While the lower body of Selam shows clear evidence of walking upright, her curved finger bones and gorilla-like shoulder blades show she retained climbing abilities. This mélange has re-ignited debates about how our early ancestors moved. "You don't just magically flip some evolutionary switch somewhere and transmute a quadruped into an upright-walking bipedal human," said Donald Johanson, who discovered Lucy in 1974, according to Scientific American.

The fossil also gives fascinating insights into early brain development. Selam's brain size, estimated at 330 cubic centimeters, is the same as that of a modern three-year-old chimpanzee. However, its brain had reached only the size of 63–88% of the adult value, while in chimps, the same percentage is about 90%, according to Max Planck Gesellschaft. Such a slower pattern of brain growth is more similar to that of modern humans and perhaps indicates a new possible behavioral shift in these early ancestors.

Another exciting and important discovery about Selam is the well-preserved hyoid bone—a complex bone with the critical task of anchoring the tongue and voice box. Its ape-like structure suggests these early human ancestors had throat anatomy more similar to modern African apes than humans, offering clues about the evolution of human speech. The environment where Selam lived puts into context her species' adaptations. Whereas today the Dikika region in Ethiopia is arid badlands, 3.3 million years ago it was a well-watered delta bordered by forests with nearby grasslands. "In this context, it is not surprising to have an ‘ape’ that spends time in the trees and on the ground," said René Bobe of George Washington University, a team member on the project, stated Scientific American.