By Pallab Ghosh
Science correspondent, BBC News, Addis Ababa
A tropical storm beats against the national museum in Addis Ababa. The violent thunder and lashing rain contrasts with the serene activity within.
Zeresenay Alemseged and the skull of "Lucy's baby"
Inside a solitary figure is cleaning up a 3.3-million-year-old skull.
Dr Zeresenay Alemseged has spent five years removing sandstone, grain by grain, from his precious find.
Illuminated by a single focussed beam of light, this is intricate, delicate work: one mistake and crucial scientific detail could be lost forever.
Alemseged showed me that what has emerged are the delicate features of a creature that was part ape and part human.
"What you have here is the backbone and the thoracic and all the ribs, the shoulder blades the collar bones. But in addition, what you have here is a compete face and the sandstone impression of the brain of a 3.3-million-year-old infant."
Six years ago Alemseged set off toward the north-eastern deserts of Ethiopia. Working in the blistering heat, his team discovered what he thought was the skull of a creature that was one of the first apes to have walked on two feet.
Unable to contain his excitement, the scientist called his friend Tefera Ghedamu.
"He said I think I got it! And he knew exactly what he'd got. He's a very cautious person, a very shy person - but then he knew and told himself, 'this is the bone'," Ghedamu recalls.
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Alemseged had found the most complete skeleton to date of a species called Australopithecus afarensis, thought to be an important pre-cursor to the first true humans.
Not only was it in a fantastic state of preservation but the specimen was that of an infant. This combination makes the find a gold mine for those studying human evolution.
It will now be available for other specialists to study; but already Alemseged has made a number of startling discoveries. Although the baby afarensis toddled on two feet like a human child, it also had many important ape-like features.
"The shoulder blades are very gorilla-like and it may ignite old questions about whether afarensis could climb trees or not. But what was really exciting was to find the tongue bone. We will, based on this bone, be able to understand what the voice box was like and about the kind of sound this creature made," he explains.
Initial thoughts suggest the bone is ape-like and that the creature probably sounded like a chimp.
'On the cusp'
What really excites Alemseged, however, is his study of the ape-girl's brain.
He believes it is still developing. Slow and gradual development in an extended childhood is a uniquely human feature - probably to enable our higher functions to fully develop.
So, according to Alemseged, this infant and her like may have been the first to show real human-like characteristics
"It's the earliest girl ever found with a mix of features that are ape-like and human-like at the same time, and this puts her in a special position to play a pivotal role. She is on the cusp of humanity," he says.
Alemseged is the first Ethiopian team leader to make such a find
The creature is the latest of many recent fossil finds important to the understanding of human evolution - the most famous of which was the first Australopithecus afarensis specimen - and adult nicknamed "Lucy" - in 1974.
It has prompted the Ethiopia's culture minister, Mahmud Dirr Gade, to invite more scientists to come to the African nation to help unearth humankind's origins.
"We welcome researchers to delve into the secrets and mystery of the creation of man in Ethiopia; the 'home of humanity'," he tells me.
Zeresenay Alemseged is the first Ethiopian to lead a research team that has made such an important discovery.
He is a bright young scientist who has studied in the US and Europe and is currently attached to the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany.
Human anthropology is a cut-throat field, even for those who have established themselves and have the backing of big funding bodies.
Ethiopia is critical to the understanding of human evolution
So, according to Tefera Ghedamu, it is especially remarkable that an outsider like Alemseged has worked his way up and to win the respect of the scientific community - and the pride of his nation.
"From my angle, from an ordinary Ethiopian's point of view, they think it is quite a heritage. They are proud that the discovery has been made in Ethiopia and they are proud that it's been made by one of their own," he says.