Lucy home after 5-year US tour

[Image] Malapa Hominin 1 (left), Lucy (centre) and Malapa Hominin 2 (right), showing the difference in height between A. sediba and A. afarensis.
(Image: Lee Berger, Wits University)

[Image] A reconstruction of what Lucy might have looked like, by award-winning palaeoartist Elisabeth Daynes.
(Image: Atelier Daynes)

[Image] The Hadar region in Ethiopia, where Lucy was found.

[Image] Family tree showing the existing hominoids: humans (genus Homo), chimpanzees and bonobos (genus Pan), gorillas (genus Gorilla), orangutans (genus Pongo), and gibbons (four genera of the family Hylobatidae: Hylobates, Hoolock, Nomascus, and Symphalangus). All except gibbons are hominids.
(Images: Wikipedia)

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Ethiopia’s grand old lady Lucy – the 3.2-million-year-old fossil discovered in 1974 – has come home after touring the US for the last five years. Her return was enthusiastically celebrated by her compatriots, who consider her an icon of human evolution.

Lucy is a specimen of the hominid species Australopithecus afarensis, which walked the earth between 3.9-million and 2.9-million years ago. South Africa’s A. sediba, which lived about two-million years ago, is thought to possibly be a link between Lucy’s species and our own.

Taxonomically, hominids, or Hominidae, belong to a family of primates, which include four living genera, namely humans; gorillas; orangutans; and chimpanzees and bonobos. Australopithecus is one of the extinct genera in the family. One of the notable characteristics of the family is the ability to walk upright.

Fossils belonging to A. afarensis have only ever been found in North Africa, and Lucy is no exception – she was unearthed at Hadar, a village in the Awash Valley in Ethiopia’s Afar Triangle. This is the origin of her species name. She is also known by her catalogue name of AL 288-1, signifying Afar Locality, the site’s number, and the first fossil discovered there.

This region is known for its wealth of archaeological finds; they include the Gawis cranium, most of the top of the skull of what scientists believe to be a human ancestor from the Middle Pleistocene period (about 781-thousand to 126-thousand years ago). It also encompasses the Gona river, where stone tools dating back 2.6-million years were found between 1992 and 1994.

Throwing off Ethiopia’s negative image

The US trip marked the first time that Lucy, known locally as Dinknesh (“special” or “wonderful” in Amharic), had left her home country. Before the jet-setting fossil went abroad, she had been stored in a special vault at the National Museum in Addis Ababa.

The tour was titled Lucy’s Legacy: The Hidden Treasures of Ethiopia, and it featured over 140 other cultural and religious artefacts, both ancient and modern.

Although she was accompanied by a team of scientists and security personnel, there was some opposition to the initiative, mainly because of fear that Lucy would be damaged. One of the objectors was National Museum researcher Berhane Asfaw, who was quoted as saying that he was the first to object and even though she’s returned he still is not convinced it was necessary to send Lucy away.

The tour took in 11 US cities, including Houston, Seattle, New York, and Austin.

A portion of the tour’s proceeds, said to be around US$1.5-million (R14.3-million), was allocated to the museum to help it upgrade its research facilities. The tour was also aimed at raising Ethiopia’s profile as a tourism and science destination.

Breakthrough discovery

Lucy was discovered on 24 November 1974 by US paleoanthropologist Donald Johansen and graduate student Tom Gray, while the two were mapping the area. A white bone caught their attention, and one glance told them it was a hominid ulna – a bone from the forearm. Investigating further, they found more fragments, and eventually managed to collect 40% of the skeleton, including a lower jaw, skull and pelvis. Because none of the bones and bone fragments were duplicated, the team realised they had come across the remains of a single person.

Her informal name comes from the famous Beatles’ song “Lucy in the Sky with Diamonds”, played over and over by the team during their celebrations just after the find.

She is thought to be a female because of the width of her pelvic opening, and because her size is consistent with the trend seen at Hadar of males being bigger and females being smaller – Lucy is a little lady. While alive she stood about 105cm tall and weighed just 29kg. Physically, she looked similar to a chimpanzee, with an ape-sized brain too.

Although her species was able to live in trees, Lucy’s petite skeleton also shows evidence that she walked upright – her knee cap has a prominent lip which prevents it from slipping out of position as weight shifts from leg to leg during walking, and the surfaces of her knee joint are adapted to the extra weight they need to carry in the upright position. Also, Lucy’s pelvis and vertebrae show typical adaptations, such as a spinal curve, needed to cope with a permanent upright stance.

Her humerus (upper arm) to femur (upper leg) ratio is 84.6%, a figure obtained by dividing the length of the humerus by the length of the femur and multiplying by 100. In contrast, this figure is 97.8% for chimps, indicating long arms for climbing trees, and 71.8% for modern humans. Lucy’s dimensions indicate that either her legs were lengthening, or her arms were getting shorter, or both.

The researchers are of the opinion that Lucy was a vegetarian. They found no clues as to the manner of her death, as her bones showed no signs of damage from scavengers. Lucy was already an adult when she died, because her cranial bones had fused and her wisdom teeth – the third pair of molars – had emerged and were slightly worn.

According to Johansen, Lucy is important not because she’s the oldest or best-preserved fossil – she is neither – but because her species is located on the human family tree at a “pivotal point”. At that time there was a split leading to the development of two branches – one leading to the human genus Homo, and one that died out.

Until just a few years ago Lucy was the oldest hominid fossil known. The discovery in 1994 of Ardi, a female of the early human-like species Ardipithecus ramidus, eclipsed even Lucy, as the newcomer was estimated to be about 4.4-million years old.