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LUCY OR DINKENESH, 3.2 MILLION YEARS AGO

Let us fast forward another 4 million years to one of the most iconic discoveries: Lucy, a celebrity in the world of palaeontology. She was a member of a species known as Australopithecus afarensis, and was named after the Beatles song Lucy in the Sky with Diamonds, which was playing on the camp radio when she was discovered in Harar in eastern Ethiopia in 1974. Lucy is known as Dinkenesh in Ethiopia, meaning 'you are marvellous' in the Amharic language, and it is how I refer to her.

There is a model of what Dinkenesh would have looked like at the National Museum of Ethiopia in the capital Addis Ababa. The real skeleton of Dinkenesh is under lock and key in a climatically controlled room, where the temperature is maintained at an optimum level for the preservation of her remains. An impressive 40 per cent of her skeleton was found, and its constituent parts are kept in carefully identified and classified pieces placed in special padded drawers. It was wonderful to see and touch Dinkenesh's bones under the supervision of Professor Yohannes Haile-Selassie, a leading Ethiopian palaeontologist. He described her as 'the icon of palaeoanthropology', adding that experts like him are still learning a lot from her.

Yohannes proceeded to tell me how Dinkenesh lived 3.2 million years ago. A reconstruction of her head shows that its lower half points forward, unlike the flat faces of modern humans, and that her brain was no bigger than that of an ape. Her jaw was relatively small but her teeth were large. An adult, she stood about a metre tall and weighed just under 30kg. She regularly walked on two legs, freeing up her arms, which were relatively longer than ours. Dinkenesh would have used her hands to make simple tools like sharpened twigs in order to fish, dig out termites or kill small animals. Fossilised turtle and crocodile eggs were found near where she died, and support the theory that she foraged for food, possibly by raiding reptile nests. Still, Dinkenesh would mainly have enjoyed a plant- and fruit-based diet.

Dinkenesh probably slept in trees for safety. One theory holds that she may have died by falling from a tree—ironically, peril lay in her refuge. Despite her superstar status in hominin history, modern humans are not direct descendants of Dinkenesh. But she is still part of the lineage that eventually led to us.

 

TAUNG CHILD, 2.8 MILLION YEARS AGO

The first evidence of a 'hominin' was discovered much earlier. Professor Raymond Dart found the Taung Child in a limestone formation at Taung near Kimberley, in South Africa's Northern Cape province in 1924. Taung Child lived about 2.8 million years ago and is from a species of hominins called Australopithecus africanus. I went along to the University of the Witwatersrand in Johannesburg, where he is kept. The prominent South African palaeoanthropologist Professor Francis Thackeray pointed out the braincase of the skull and the front of the face and lower jaw, and explained that for decades it was thought that our hominin ancestors were voracious predators, or 'killer apes'. Some nearby eggshells were accordingly interpreted as the child's lunch, but showing me the cracks in the Taung Child's skull and eye-sockets, he told me that in the 1990s scientists like him began to notice that the damage looked similar to that of modern monkeys killed by eagles. It seems that the Taung Child was not at home in his cave, but in the lair of a huge bird of prey, probably an ancient eagle, which killed him and dragged him there. It is a window into a time when our forebears were both predator and prey. Taung Child was the first hominin to be found in Africa, and he appeared much more archaic than other remains found elsewhere at the time. He provided the first hint that Charles Darwin may have been correct about humans originating in Africa.

MRS PLES, 2.5 MILLION YEARS AGO

Some 20 years after the discovery of the Taung Child, South African palaeontologists Robert Broom and John T. Robinson uncovered a pre- human skull in the caves of Sterkfontein, north of Johannesburg, in 1947. She was called Mrs Ples as a snappier alternative to the initial scientific name, Plesianthropus transvaalensis. After 2 million years of peaceful entombment, Mrs Ples's head was blown up by the dynamite of a lime mining operation. Scientists have pieced it back together, and it is now almost complete. Mrs Ples, like Dinkenesh, had a small brain, similar in size to those of chimpanzees, and about a third of ours, but she walked on two legs. She was a significant find; her skull proved for the first time that walking upright had evolved well before any significant growth in brain size. Experts can gauge whether a hominin walked on two legs from a hole at the back of the skull called the 'foramen magnum' through which the vertebrae and spinal cord enter. Mrs Ples had such a hole and it pointed downwards, indicating she had been bipedal.

Different kinds of hominins co-existed in Africa and scientists are constantly trying to work out how various types such as the Taung Child, Mrs Ples and Dinkenesh are related, but what we do know is that as various lines died out, just one, the "Homo genus, led directly to us modern humans. This is where the detective work shifts eastwards on the continent.