No bigger than a cantaloupe, the little bundle of bones may also bear witness to a key event in the evolution of hominins, as humans and their ancestors are known: the beginning of our long, dependent childhood, when we grow our large brains. "Outside of its completeness, the major importance of this find is the light it will shed on how this species lived and grew," says Bill Kimbel, an expert on A. afarensis and a member of the study team. "Now we can begin to read its biography."
It is a curious coincidence that the world's oldest baby, who died while still of nursing age, lived her short life in a region named Dikika—"nipple" in the local Afar language, after a distinctly shaped hill. The hill is just across the winding Awash River from Hadar, the site in Ethiopia's Rift Valley where Lucy and the fossils of many other hominins have been found. The region is plagued by extreme heat, flash floods, malaria, and occasional shoot-outs between rival ethnic groups, not to mention lions, hyenas, and other uninvited nocturnal guests. It is one of the most difficult places on Earth to hunt for fossils—and one of the most fruitful.
For decades the low-lying northern end of Africa's Great Rift Valley, the Afar depression, has been the domain of foreign-led expeditions. Zeresenay, one of a new generation of Ethiopian paleoanthropologists, changed that in 1999 when he led a band of Ethiopian fossil hunters into the Afar badlands.
By December 2000, the search had turned up plenty of fossil mammals, such as elephants, hippopotamuses, rhinoceroses, and antelopes, but no hominins. Yet Zeresenay, who is based at the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany, knew his team was looking in the right place. These animals would have thrived in the gallery forest that flanked the ancestral Awash River. Early hominins would have lived in these shady woodlands as well.
The prehistoric forests of Dikika are long gone, and there was no shade on December 10, when team members forced themselves out into the hot sun to look again. Tilahun Gebreselassie was the first to see the Dikika baby's tiny face peering out from a dusty slope. It was no bigger than a monkey's, but a smooth brow and short canine teeth told Zeresenay right away that this was a small hominin. His team had struck fossil gold, for not only was the baby's skull in perfect shape, but tucked beneath the head in a hard ball of sandstone were many bones of the upper body as well. "This is something you find once in a lifetime," Zeresenay says.